High-R Walls for 

Remodeling: Wall Cavity 

Moisture Monitoring

J. Wiehagen and V. Kochkin

NAHB Research Center

December 2012
NOTICE

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iii

High-R Walls for Remodeling:

Wall Cavity Moisture Monitoring

Prepared for:

The National Renewable Energy Laboratory 

On behalf of the U.S. Department of Energy’s Building America Program

Office of Energy Efficiency and Renewable Energy

15013 Denver West Parkway

Golden, CO 80401

NREL Contract No. DE-AC36-08GO28308

Prepared by: 

J. Wiehagen and V. Kochkin

NAHB Research Center Industry Partnership

400 Prince George’s Blvd

Upper Marlboro, MD 20774

NREL Technical Monitor: Stacey Rothgeb

Prepared under Contract No. KNDJ-0-40335-00

December 2012
iv

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v

Contents

List of Figures ............................................................................................................................................ vi

List of Tables ............................................................................................................................................. vii

Definitions................................................................................................................................................. viii

Executive Summary................................................................................................................................... ix

1 Purpose ................................................................................................................................................. 1

2 Introduction........................................................................................................................................... 1

3 Background........................................................................................................................................... 2

3.1 Field Observations...............................................................................................................2

3.2 OSB Sheathing Characteristics............................................................................................3

4 Research Methodology........................................................................................................................ 4

4.1 Research Homes...................................................................................................................4

5 In-Service Environmental Conditions Monitoring........................................................................... 14

5.1 Monitoring System.............................................................................................................15

5.2 Monitoring Sensor Locations.............................................................................................15

6 Results of In-Service Environmental Conditions Measurements.................................................. 17

7 Data Comparisons.............................................................................................................................. 29

7.1 Cavity Temperatures..........................................................................................................30

7.2 Cavity Relative Humidity ..................................................................................................33

7.3 Cavity Dew Point Temperatures........................................................................................36

7.4 Oriented Strand Board Moisture Content ..........................................................................39

7.5 Oriented Strand Board Moisture Content and Relative Humidity.....................................42

8 Analysis Based on ASHRAE 160-2009 ............................................................................................. 45

9 Summary ............................................................................................................................................. 46

10 Initial Results and Observations....................................................................................................... 47

11 Ongoing Moisture Research and Next Steps .................................................................................. 48

References................................................................................................................................................. 49

Bibliography .............................................................................................................................................. 50

Appendix: Site Inspection Data Sheet .................................................................................................... 51
vi

List of Figures

Figure 1. Wavy lap siding resulting from buckled OSB panels on the rear wall of a house............... 3

Figure 2. Wavy siding resulting from buckled OSB panels on a side wall of a house ........................ 3

Figure 3. Removed buckled OSB panel.................................................................................................... 3

Figure 4. Wall with buckled OSB panels (siding removed exposing the weather-resistive barrier). 3

Figure 5. Jobsite geographical locations overlay on the DOE climate and hygrothermal map ......... 5

Figure 6. Comparison of precipitation amounts for each jobsite location ........................................... 8

Figure 7. Common wall detail for monitored homes ............................................................................... 9

Figure 8. Jobsite 1 test wall location and orientation ........................................................................... 10

Figure 9. Jobsite 2 test wall location and orientation ........................................................................... 10

Figure 10. Jobsite 3 test wall location and orientation ......................................................................... 11

Figure 11. Jobsite 4 test wall location and orientation ......................................................................... 11

Figure 12. Jobsite 5 test wall location and orientation ......................................................................... 12

Figure 13. Jobsite 6 test wall location and orientation ......................................................................... 12

Figure 14. Jobsite 2 east wall (test wall highlighted), three stories framed ....................................... 14

Figure 15. Omnisense S-900-1 sensor.................................................................................................... 15

Figure 16. Installed test wall moisture sensors ..................................................................................... 15

Figure 17. Jobsite 1 OSB MC, all available data .................................................................................... 20

Figure 18. Jobsite 2 OSB MC, all available data .................................................................................... 21

Figure 19. Jobsite 3 OSB MC, all available data .................................................................................... 22

Figure 20. Jobsite 5 OSB MC, all available data .................................................................................... 23

Figure 21. Jobsite 6 OSB MC, all available data .................................................................................... 24

Figure 22. Example of an elevated OSB MC in one wall section showing seasonal changes in MC25

Figure 23. Jobsite 2 delta cavity temperature minus DP temperature (negative values indicate 

condensation potential)..................................................................................................................... 26

Figure 24. Jobsite 5 delta cavity temperature minus DP temperature (negative values indicate 

condensation potential)..................................................................................................................... 27

Figure 25. Jobsite 5 comparison of MC and DP .................................................................................... 28

Figure 26. Jobsite 5 MC comparison of all wall cavities....................................................................... 29

Figure 27. Jobsite 1 temperatures........................................................................................................... 30

Figure 28. Jobsite 2 temperatures........................................................................................................... 31

Figure 29. Jobsite 3 temperatures........................................................................................................... 31

Figure 30. Jobsite 5 temperatures........................................................................................................... 32

Figure 31. Jobsite 6 temperatures........................................................................................................... 32

Figure 32. Jobsite 1 RH values ................................................................................................................ 33

Figure 33. Jobsite 2 RH values ................................................................................................................ 34

Figure 34. Jobsite 3 RH values ................................................................................................................ 34

Figure 35. Jobsite 5 RH values ................................................................................................................ 35

Figure 36. Jobsite 6 RH values ................................................................................................................ 35

Figure 37. Jobsite 1 DP temperatures..................................................................................................... 36

Figure 38. Jobsite 2 DP temperatures..................................................................................................... 37

Figure 39. Jobsite 3 DP temperatures..................................................................................................... 37

Figure 40. Jobsite 5 DP temperatures..................................................................................................... 38

Figure 41. Jobsite 6 DP temperatures..................................................................................................... 38

Figure 42. Jobsite 1 MC............................................................................................................................ 39

Figure 43. Jobsite 2 MC............................................................................................................................ 40

Figure 44. Jobsite 3 MC............................................................................................................................ 40

Figure 45. Jobsite 5 MC............................................................................................................................ 41

Figure 46. Jobsite 6 MC............................................................................................................................ 41

Figure 47. Jobsite 1 MC relative to humidity.......................................................................................... 42

Figure 48. Jobsite 2 MC relative to humidity.......................................................................................... 43

Figure 49. Jobsite 3 MC relative to humidity.......................................................................................... 43

Figure 50. Jobsite 5 MC relative to humidity.......................................................................................... 44

Figure 51. Jobsite 6 MC relative to humidity.......................................................................................... 44
vii

Unless otherwise noted, all figures were created by the NAHB Research Center Industry 

Partnership.

List of Tables

Table 1. Jobsite and Home Details............................................................................................................ 6

Table 2. Wall Details.................................................................................................................................... 7

Table 3. Home Construction Dates ........................................................................................................... 8

Table 4. OSB Panel Properties and Installation Details........................................................................ 13

Table 5. Sensor Locations by Jobsite..................................................................................................... 16

Table 6. Potential OSB Panel Expansion................................................................................................ 17

Table 7. Summary Wall Cavity Moisture Characteristics for Latest Annual Period........................... 18

Table 8. Standard 160 Condition Criteria Necessary To Minimize Mold Growth................................ 45

Table 9. Wall Cavity Analysis of Standard 160 Criteria......................................................................... 45

Unless otherwise noted, all tables were created by the NAHB Research Center Industry 

Partnership.
viii

Definitions

ACH50 Building air changes per hour at a 50 pascal interior pressure 

differential with respect to the exterior 

AFUE Annual fuel utilization efficiency

BA Building America 

DOE U.S. Department of Energy 

DP Dew point

HSPF Heating season performance factor, representative of the 

efficiency rating of electric heating equipment

ICC International Code Council

IECC International Energy Conservation Code

MC Moisture content; relating to wood properties, the moisture 

content is defined as the weight of the water contained in the 

wood expressed as a percentage of the oven dry weight of the 

wood.

NAHB National Association of Home Builders

OSB Oriented strand board

PS2 Performance standard for wood-based structural-use panels

RH Relative humidity

SEER Seasonal energy efficiency ratio, a measure of the efficiency 

of consumer central air-conditioning systems

SPF Spruce-Pine-Fir

T Temperature

Vinyl Vinyl siding used as the outermost exterior finish

WRB Weather-resistive barrier
ix

Executive Summary

The National Association of Home Builders (NAHB) Research Center Industry Partnership team 

monitored six homes constructed in 2009 for wall cavity moisture characteristics. Five of the 

homes were constructed in climate zone 5 and one in climate zone 4. The monitoring program 

was initiated from an experience of oriented strand board (OSB) sheathing problems (buckling

and siding displacement) in similar homes constructed in the same geographic area to

characterize the wall moisture. The homes under test were constructed using code-compliant 

wall construction practices and materials using an exterior weather-resistive barrier on the 

exterior of the wood structural sheathing. The homes were all tested to air infiltration levels of 

fewer than four air changes per hour at 50 Pa. The monitoring program was designed to identify 

seasonal moisture characteristics that might indicate the potential for problems as well as 

produce a baseline set of data for comparison to homes constructed with higher performing 

(better insulated) wall systems.

One suspected interaction that might lead to moisture problems, including sheathing buckling,

was increased winter moisture levels in the cavity because of a combination of lower infiltration 

rates (of colder, drier air in winter) resulting from a combination of air sealing strategies and 

interior winter moisture levels that raise humidity levels in the home. The wall cavity and 

sheathing monitoring results presented here provide empirical data on the cyclic moisture 

characteristics of wall cavities in higher efficiency homes that are a precursor to subsequent data 

from high performance wall systems in homes constructed to building energy code levels at or 

exceeding those outlined in the International Energy Conservation Code (International Code 

Council 2012). The monitored data in particular include the moisture content of the wood 

structural sheathing, a primary indicator of OSB expansion.

The results of the monitoring period reported for each home indicated a wide range of cavity 

moisture characteristics that are generally seasonal and directional, with the colder periods and 

the east and north walls showing the higher instances of moisture content (MC). All wall cavities 

measured show a cyclic behavior for the OSB MC but with a wide variation in the both the peak 

moisture content and the duration of higher levels of MC measured. Often, wide variations occur 

within the same home. 

Results of this study will help create a baseline for the next study that is currently under way,

focusing on the moisture performance of high R-value wall systems in energy efficient homes

throughout multiple climate zones. The next phase of this research will look at a range of wall 

systems and construction configurations, upgraded to meet or exceed the minimum insulation 

levels and airtightness requirements of current energy codes. The focus of the study is on the 

performance of wall systems and, in particular, the moisture characteristics inside the wall cavity 

and in the wood sheathing. Furthermore, although this research will initially address new home 

construction, the goal is to resolve potential moisture issues in wall cavities of existing homes 

when insulation and air sealing improvements are made. 
1

1 Purpose

This study, which was performed by the National Association of Home Builders (NAHB) 

Research Center Industry Partnership, was initiated to characterize indoor humidity levels and 

wall cavity moisture performance in standard constructed wall systems in homes air sealed 

beyond standard building code requirements. This initial work will also support ongoing efforts 

to address the moisture performance of much higher efficiency wall systems. Furthermore, 

although this research will initially examine new home construction, the goal is to resolve 

potential moisture issues in wall cavities of existing homes when insulation and air sealing 

improvements are made in older homes. 

The objectives of the study were to document seasonal wall cavity moisture characteristics, 

document oriented strand board (OSB) moisture characteristics and indoor humidity levels in 

homes with substantially lower infiltration rates, and with sufficient data, isolate the variables or 

a combination of variables that can result in unsatisfactory moisture performance of standard 

acceptable wall system construction. 

The purpose of this initial effort was to document construction practices and obtain wall cavity 

moisture performance data for occupied homes framed in the fall of 2009 in the same 

geographical areas and by the same builders that experienced buckling of OSB wall sheathing in 

the winter of 2008–2009. The specific buckling issue raised concerns for builders that combining 

higher efficiency home features might lead to more wall cavity moisture problems. Based on the 

unexpected wall sheathing failures in homes constructed according to current code practices and 

similarly to many homes that apparently do not have moisture problems, this study was 

organized to investigate the cyclic moisture characteristics in the wall cavity. Documenting the 

moisture characteristics in wall cavities of these standard wall details and operating in 

uncontrolled but common field conditions was deemed necessary to correlate wall construction 

methods and materials with the cavity moisture performance. This documentation is important to 

not only uncover potential problems but also to correlate similar characteristics in other, more 

efficient wall system designs. 

2 Introduction 

Overall, the goal of the U.S. Department of Energy’s (DOE) Building America (BA) program is 

to “demonstrate how cost-effective strategies can reduce home energy use by up to 50%, for both 

new and existing homes, in all climate regions by 2017.” To this end, the BA teams conduct 

research to “design, test, upgrade, and build high performance homes using strategies that 

significantly cut energy use.” (DOE 2012a).

The changes in the moisture performance of the wall system can have serious negative effects on 

the building durability, indoor environmental quality, and even comfort without immediate signs 

to the home occupant. The NAHB Research Center’s moisture research is designed to yield 

information on the moisture performance of upgraded existing and new energy efficient homes 

with higher performing wall systems. The testing detailed in this report provides baseline data 

for standard home construction with lower infiltration levels than standard homes. The next 
2

phase of this research will look at wall systems upgraded to meet or exceed the minimum 

insulation levels and airtightness requirements of the International Energy Conservation Code

(IECC; International Code Council [ICC] 2012). The focus of the study is on the performance of 

wall systems and, in particular, the moisture characteristics inside the wall cavity and in the 

wood sheathing. Furthermore, this study will initially consider new home construction, but the 

goal is to resolve potential moisture issues in wall cavities of existing homes when insulation and 

air sealing improvements are made. 

Increasing insulation levels in wall systems is a key element in achieving current and new BA 

goals for energy performance. Technologies and construction methods to accommodate higher 

levels of insulation are often based on typical construction methods that serve multiple purposes,

including structural and fire safety. At the same time, walls constructed using these methods are 

expected to last for many decades and to function as a neutral aspect to the environmental quality 

of the indoor air (e.g., not contribute to mold and decay).

This field testing parallels other BA research in that higher R-value walls must be demonstrated

to perform satisfactorily as a material and to last for the life of the home. Higher R-value wall 

systems are expected to perform thermally as designed; this research focuses on ensuring that the 

changes to the wall system design and their construction will continue to perform like the wall 

systems used successfully for generations.

The monitoring details outlined here in climate zone 4 and the ongoing expanded research will 

analyze wall moisture performance in multiple climate zones except for hot-dry climates. The 

data obtained through this monitoring effort are expected to serve as empirical evidence of the 

wall system moisture performance throughout multiple seasons, climate zones, and houses with 

lower infiltration. In addition, for some test homes, these data will be combined with energy 

consumption data and ventilation data to give an overall characterization of the whole-house 

energy and moisture performance that can then be used to compare with models that predict such 

results. 

3 Background

3.1 Field Observations

Some builders in the midwestern states and Pennsylvania reported an apparent increase in OSB 

wall sheathing buckling was reported during the winter season of 2009. The homes with reported 

OSB buckling are located in cold climates (climate zones 5 and 6) or at the boundary between 

the cold and mixed-humid climates (zone 4).

The team interviewed several builders who experienced this problem. The problem manifested 

itself as “wavy” vinyl siding (Figure 1 through Figure 4). The repairs typically involve removing

the siding and replacing buckled OSB panels. Evidence of the panels having elevated moisture 

levels was observed during the repairs, including in some cases observations of a “mold-like 

substance” on the interior face of the panel. During repairs made in the winter months, in some 

cases, frost was also observed on the exterior face of the panel. 
3 

Figure 1. Wavy lap siding resulting from buckled 

OSB panels on the rear wall of a house

Figure 2. Wavy siding resulting from

buckled OSB panels on a side wall of a 

house

Figure 3. Removed buckled OSB panel Figure 4. Wall with buckled OSB panels 

(siding removed exposing the weatherresistive barrier)

3.2 OSB Sheathing Characteristics

OSB panels are made of wood strands oriented and glued together. Because wood changes 

dimensions as it releases or gains moisture, the OSB panels expand as the moisture content (MC) 

of wood increases in response to the ambient conditions. All OSB panels are required to meet the 

linear expansion limits of Product Standard PS-2 (1) (NIST 2004) for a maximum average 

expansion of 0.5% in either panel direction (machine and cross machine) when subjected to a 

controlled laboratory MC change of about 19%. 
4

OSB panels typically arrive at the jobsite at low MC (e.g., 5%). The OSB manufacturers’ 

installation instructions require a 1⁄8-in. gap between the vertical panel joints to allow limited 

expansion of the panels. If the expansion of the panel exceeds the provided gap, the panels are 

prone to buckling in the direction perpendicular to the wall’s plane. For a 48-in.-wide panel with 

a linear expansion of 0.5%, installed with a 1⁄8-in. gap, the calculated maximum MC change for 

panels to come into full contact without additional room to expand is about 10%. As the team

observed during this study, MCs of OSB above 20% and even above 25% are not uncommon in 

walls in the initial months following the construction process (and in some cases later in 

service)―resulting in a total potential moisture fluctuation of 15%–20% relative to the initial 

starting point of 5%. Sheathing fasteners help restrain the expansion of panels in a wall 

assembly. A follow-up laboratory study is planned to investigate the relationship between the 

panel properties and the panel expansion and buckling behavior when attached to wall framing.

4 Research Methodology 

The research methodology includes the following primary steps:

1. Identifying new homes built in fall 2009 by the same builders in the same 

geographical areas that experienced OSB buckling in spring 2009

2. Observing OSB installation on each selected home

3. Collecting relevant design, construction, and material data for each selected home

4. Installing sensors in walls to measure temperature, dew point (DP), and relative 

humidity (RH) inside the cavity and MC of OSB sheathing

5. Measuring air exchange rates through blower door testing for each selected home

6. Collecting and analyzing data

7. Developing conclusions based on the documented performance.

This report summarizes results of steps 1 through 5 on six homes, and the remaining steps on 

five of the homes. An analysis of the available wall cavity measured moisture performance data 

collected is included. Conclusions are drawn based on the analysis completed to date. 

4.1 Research Homes

Three homebuilders in three different states made six homes/jobsites in climate zones 4 and 5 

(Figure 5) available to the NAHB Research Center. A site visit was conducted for each home 

during the construction process. A Site Inspection Data Sheet (see Appendix) was completed for 

each home/jobsite to document construction details, home design, and material characteristics. 

Table 1 summarizes key characteristics for each home. Table 2 contains wall assembly details.
5

Figure 5. Jobsite geographical locations overlay on the DOE climate and hygrothermal map

(Source: Building America website - DOE 2012b)

Because the building’s airtightness is important to its moisture performance, blower door tests 

were conducted on each home to measure the amount of air changes per hour at 50 Pa (ACH50). 

The blower door tests were performed after completion of construction and before occupancy. 

Table 1 includes results of the blower door tests.

Jobsite 6 Jobsite 2

Jobsite 5

Jobsite 1 Jobsite 3

Jobsite 4
6

Table 1. Jobsite and Home Details

Jobsite 

Number City State Climate Zone

ENERGY 

STAR

Blower 

Door 

ACH50 a

Square 

Footageb

(ft2

)

Number of 

Occupants

Basement Attached Garage Heating 

System

Cooling 

System Ventilation Fireplace

Conditioned Finished Conditioned Finished

1 Chesterfield MO 4 Yes 2.49 5,700 Model 

Home Yes Yes Yes Yes

Gas 

(92.1 

AFUE)

Electric 

(SEER14)Unknownc Gas

2 Valencia PA 5 Yes 2.41 5,300 3 Yes No No Yes

Electric 

(8.0 

HSPF)

Electric 

(SEER13)Kitchen/Bathrooms Wood

3 Mansfield OH 5 No 2.12 4,000 4 Yes No No Yes

Electric 

(8.1 

HSPF)

Electric 

(SEER13)Kitchen/Bathrooms No

4 Wadsworth OH 5 Yes 3.71 3,000 2 Yes No No Yes Gas (93 

AFUE)

Electric 

(SEER14)Whole-house No

5 Lorain OH 5 No 3.27 2,800 4 Yes No No Yes

Gas 

(92.3 

AFUE)

Electric 

(SEER13)Kitchen/Bathrooms No

6 North 

Ridgeville OH 5 No 2.83 3,000 3 Yes Partial No Yes

Gas 

(92.3 

AFUE)

Electric 

(SEER13)Kitchen/Bathrooms No

Notes: AFUE, annual fuel utilization efficiency; SEER, seasonal energy efficiency ratio; HSPF, heating season performance factor

a. Depressurization blower door test results reported. The blower door test results are developed from multipoint depressurization test results.

b. Home square footage includes the basement. 

c. The information provided by the builder on this house is inconsistent with the plan specifications. 
7

Table 2. Wall Details

Jobsite 

Number City State Framed Stories

Framing 

Sizea,b

Stud 

Material/ 

Grade

Stud 

MCc (%) Air Sealing

Wall 

Insulation/ 

Vapor 

Retarder

WRB

(Permsd

) Finish

1 Chesterfield MO 2 2 × 4 SPF/Stud 9-17 Sill, Rim 

Joist

R-13/ 

Kraft paper

Brand 1 

(46.6)

Brick and Cement 

Fiber Board

2 Valencia PA 3 2 × 6 SPF/Stud 11-15

Plates (top, 

bottom, and 

sill), Rim 

Joist 

R-19/ 

Kraft paper Brand 2 (56) Brick, Stone, and Vinyl

3 Mansfield OH 2 2 × 4 SPF/Stud 9-15

Plates (top, 

bottom, and 

sill), Rim 

Joist

R-13/ 

Kraft paper Brand 2 (56) Vinyl

4 Wadsworth OH 1 2 × 4 SPF/Stud 10

Plates (top, 

bottom, and 

sill), Rim 

Joist

R-15/ 

Kraft paper Brand 2 (56) Vinyl

5 Lorain OH 2 2 × 4 SPF/2 12-13 Bottom 

Plate

R-13/ 

Kraft paper Brand 3 (63) Vinyl

6 North Ridgeville OH 1 2 × 4 SPF/Stud 8-14 Bottom 

Plate

R-13/ 

Kraft paper Brand 3 (63) Vinyl

a. Spruce-Pine-Fir (SPF) typical wood species for all jobsites

b. Stud spacing of 16 in. on center used for all jobsites

c. Framing MC measured during site visit

d. Perm ratings for WRBs obtained from product specifications physical properties data sheets [Dow, 2010], [DuPont 2007]
8

Table 3 gives specific dates for construction of each home. All homes were framed primarily in

November. Occupancy of the homes began in January and February 2010. Figure 6 shows the 

total precipitation by month during the time of construction for each site, including historical

monthly averages for comparison. Generally, total precipitation during the observation period 

measured below historical monthly averages except for October and January, when precipitation 

levels were higher than average. Table 3 also includes the dates of the NAHB Research Center 

site visits. NAHB Research Center staff was present at the time of the wall framing only for 

jobsite 1 (Chesterfield, Missouri). For the other five sites, the visit was conducted a few days 

after the framing had been completed and the wall framing was still exposed.

Table 3. Home Construction Dates

Jobsite 

Number

Foundation 

Start

Framing 

Start

Roof 

Enclosed

House 

Enclosed

Occupancy 

Start

NAHB Research 

Center Site Visit

1a 10/23/09 11/03/09 11/12/09 11/13/09 12/22/09 11/04/09

2 10/29/09 11/17/09 12/10/09 12/10/09 1/18/10 11/20/09

3 10/22/09 11/10/09 11/11/09 11/12/09 1/6/10 11/12/09

4 10/19/09 11/5/09 11/09/09 11/10/09 2/22/10 11/12/09

5 10/20/09 11/10/09 11/18/09 11/24/09 01/19/10 11/12/09

6 10/14/09 10/30/09 11/12/09 11/19/09 01/25/10 11/12/09

a Home is a model home, occupancy date is the date the home became open for display.

Figure 6. Comparison of precipitation amounts for each jobsite location

0

1

2

3

4

5

6

7

8

9

10

Precipitation (inches)

Date (Month-Year)

Monthly Measured Total and Historical Average Precipitation

St. Louis, MO 

(Measured Total)

Valencia, PA 

(Measured Total)

Mansfield, OH 

(Measured Total)

Wadsworth, OH 

(Measured Total)

Lorain, OH 

(Measured Total)

North Ridgeville, OH 

(Measured Total)

St. Louis, MO 

(Historic Average)

Valencia, PA 

(Historic Average)

Mansfield, OH 

(Historic Average)

Wadsworth, OH 

(Historic Average)

Lorain, OH 

(Historic Average)

North Ridgeville, OH 

(Historic Average)
9 

The walls being monitored represent the most common wall assemblies being constructed in the 

United States. Figure 7 shows a general representation of the wall detail for the homes being 

monitored. Table 2 contains a complete list of the wall configuration and materials. All of the 

homes were constructed with interior kraft-faced batt facing. Figure 8 through Figure 13 show 

first-story plans and photographs of each home. In each home, a “test wall” was selected for 

detailed documentation of the OSB installation process and monitoring of the moisture 

performance. The test walls were selected based on (1) wall orientation and (2) the amount of 

openings (i.e., doors or windows) in the wall. Because the MC in the OSB panels is the driving 

factor for panel expansion and possibly buckling, sidewalls with a northward orientation were 

the primary choice for investigation. These walls were selected because of higher expected MCs 

from reduced sun exposure, which leads to lower wall temperatures and decreased drying 

potential. The walls with fewer openings are expected to be more prone to buckling because of 

increased amounts of sheathing and cumulative expansion across the face of the wall. The test 

wall is always a first-floor side wall (left or right side elevation) with few openings and the 

majority of the wall adjacent to livable space. Panel dimensions, gapping between installed 

panels, and panel attachment details were observed and documented for each test wall (Table 4).

The OSB panels used in wall construction of the six homes came from six different mills from 

five manufacturers. Because panel linear expansion properties vary by mill based on the 

materials used in panel fabrication (e.g., wood species, strand orientation, resin type and content, 

and wax), panels are classified by manufacturer (1 through 5) and mill location (A or B). 

OSB samples were taken from wall sheathing panels at each of the jobsites for testing linear 

expansion properties. Researchers at the NAHB Research Center’s laboratory conducted the 

testing in accordance with PS-2 (National Institute of Standards and Technology, 2004). Table 4

contains the results from the linear expansion testing. Linear expansion in the machine grain 

direction was substantially below the 0.5% limit for all six mills. Linear expansion in the cross 

direction varied substantially between the mills, from as low as 0.22% to as high as 0.57%. 

Panels from Mill 2-B consistently exceed the PS-2 0.5% limit. Panels from Mill 1 and Mill 5 

were at or near the 0.5% limit.

Figure 7. Common wall detail for monitored homes
10

Figure 8. Jobsite 1 test wall location and orientation Figure 9. Jobsite 2 test wall location and orientation

Test 

wall

Test 

wall
11

Figure 10. Jobsite 3 test wall location and orientation Figure 11. Jobsite 4 test wall location and orientation

Test 

wall Test 

wall
12

Figure 12. Jobsite 5 test wall location and orientation Figure 13. Jobsite 6 test wall location and orientation

Test 

wall Test 

wall
13

Table 4. OSB Panel Properties and Installation Details

Jobsite OSB 

Mill Floor

Average MC

at 

Inspection

Panel Dimension Installed 

Vertical 

Edge Gap

(in.)

Panel 

Orientation

Fasteners Linear Expansion

Mean Deviation

Edge 

Distance

(in.)

Orientation to 

Adjoining Panel 

Edge

OverdrivenGrain 

Direction Mean

1

Mill 

1 1 <6% 47.910 0.027 0–3/16

Vertical

0–1/2 Perpendicular Partial

Machine 0.13

Cross 0.50

Mill 

2-A 2 <6% 47.934 0.023 - - - - Machine 0.07

Cross 0.22

2

Mill 

3 1 11% 48.036 0.048 0–1/8 (Footnote a)

Machine 0.10

Cross 0.25

Mill 

2-B 2 10% 47.881 0.013 - - - - Machine 0.16

Cross 0.56

3

Mill 

4 1 9% 47.948 0.0210 0–5/32 1/16–1/2 Parallel Yes

Machine 0.16

Cross 0.27

Mill 

2-B 2 8% 47.931 0.0342 - - - - Machine 0.23

Cross 0.49

4 Mill 

3 1 7% 47.972 0.025 1/32–1/8 1/2 Parallel Yes

Machine 0.13

Cross 0.28

5

Mill 

5 1 9% 48.060 0.009 1/16–1/8 0–1/2 Varies Partial

Machine 0.20

Cross 0.47

Mill 

2-B 2 <6% 47.866 0.026 - - - - Machine 0.16

Cross 0.57

6b Mill 

2-B 1 9% 95.938 0.030 0–1/8 Horizontal >1/2 Parallel No

Machine 0.16

Cross 0.57

a. At the time of the jobsite visit, OSB sheathing was covered with WRB and sheathing fasteners were not accessible for detailed inspection.

b. Linear expansion results from OSB sheathing obtained at Jobsite 5 (panels used were from the same mill and had the same manufacture date). 

“-“ indicates that data is not available for the panels from that mill. Panel separation measurements were taken from a defined test wall section in the test home with panels from a specific mill. In some 

jobsites wall panels in other wall sections than the test wall were from two different mills.
14

The home located in Valencia, Pennsylvania (Jobsite 2) had a wood framed walk-out basement 

such that one end of the home had three framed stories. The test wall for this home was at the 

second level as shown in Figure 14.

Figure 14. Jobsite 2 east wall (test wall highlighted), three stories framed

The framing on Jobsites 4 and 6 was completed before the NAHB Research Center staff visited. 

As a result, all excess OSB sheathing panels were removed from the site before the visits. For 

Jobsite 4, the builder was able to obtain OSB panels from the same manufacturer and mill; the 

unique difference between panels installed on the walls and the panels used for linear expansion 

testing was the manufacture date (installed panels manufactured September 9, tested panels 

manufactured September 3). No linear expansion samples were obtained from Jobsite 6 because 

the OSB panels were identical to those used on Jobsite 5.

5 In-Service Environmental Conditions Monitoring

Because increased moisture in the OSB panels is the primary driver for panel expansion, sensors 

were installed inside the wall cavity of the test wall and in several other reference locations of 

each house to measure the MC of the OSB panels and environmental conditions inside the wall 

cavity. In addition, one or two sensors were installed inside of each home to monitor the 

temperature and RH inside the house. The ambient weather data were obtained from local 

weather stations. This section discusses details of the environmental monitoring system and 

presents the available data for each of the jobsites. 
15

5.1 Monitoring System

Small wireless sensors (Omnisense S-900-1, Figure 15) were installed in walls in the home to 

measure the following parameters:

• Cavity temperature (–40°F to 185°F)

• Cavity RH (0% to 100%)

• Cavity DP temperature

• OSB sheathing moisture content (7% to 40%).

The temperature and RH are measured by an internal sensor located inside the plastic housing. 

The wood MC is determined using two screw pins driven into the sheathing and is based on the 

measured resistivity of the OSB material. The sensors transmit measurements at set intervals (in 

most cases, 30 min) wirelessly to a gateway (router). The gateway then uploads the 

measurements to a central website location for storage and acquisition. Figure 16 shows a typical 

installation of a sensor before enclosing with insulation.

Figure 15. Omnisense S-900-1 sensor Figure 16. Installed test wall moisture sensors

The manufacturer states that the sensor accuracy for the models used is ±2.0% RH and ±0.3°C. 

The NAHB Research Center has performed numerous calibrations to verify both sensor accuracy 

and the correlations with the MC. MC correlations have been performed comparing to readings 

on handheld electrical conductance type moisture meters as well as comparing MC readings with 

wet/oven dry sample measurement calculations. The wood MC value reported through the sensor 

technology is a wood moisture equivalent and is the water content of wood as a percentage of 

dry weight. The sensor manufacturer calibrates its devices based on wood species and 

temperature compensation relationships outlined by the U.S. Department of Agriculture (James 

1988).

5.2 Monitoring Sensor Locations

On average, eight sensors were installed in the one-story homes and 14 sensors were installed in 

the two-story homes. Sensors were attached to the inside face of the exterior OSB panel in the 

center of the wall cavity. The sensors were located at an elevation of 5 ft above the subfloor. A 

Moisture 

Content 

Screws

Internal 

Sensor

Antenna

Moisture

Sensors
16

minimum of one sensor per wall orientation (i.e., north, west, east, and south) was installed with 

three sensors installed in each test wall. In two-story homes, a minimum of three sensors were 

installed in the second floor exterior wall above the test wall. 

Table 5 describes individual sensor locations and associated wall orientation for each of the six 

jobsites. During the planning stages of this study, based on discussions with builders, the NAHB 

team determined that there was no consistency between OSB buckling and interior room use 

(e.g., bathrooms with higher humidity). Therefore, sensor locations were not predetermined 

based on adjacent interior room use.

One sensor was located in the interior of the home to monitor temperature and RH inside the 

house. Although the intention was to locate the interior sensor as near to the home’s thermostat 

as possible, because of aesthetics and homeowner preferences, the interior sensors in five of the 

six homes were located in the kitchen above cabinets. In addition, exterior daily average ambient 

temperature, RH, and DP were obtained from weather stations located near each home.

Table 5. Sensor Locations by Jobsite

Adjacent Interior 

Room Use

Number of sensors (wall orientation) 

Jobsite Number

1 2 3 4 5 6

Kitchen 2 (Interior, 

East)

1 (Interior, 

East)

1 (Interior, 

West)

1 (Interior, 

South) 1 (Interior) 1 (South)

Full Bath 1 (South) 1 (East) 1 (East)

Half Bath 1 (East) 1 (East)

Living room 3 (2-North, 

West)

2 (North, 

East)

Family room 1 (North) 2 (East, 

South)

Dining room 2 (North, 

East) 1 (East)

Great room 1 (North) 2 (North, 

West) 1 (Interior)

Bedroom/Office

5 (3-North, 

West, 

South)

5 (1-North, 

West, 2-

East, South)

4 (North, 2-

East, South)

4 (West, 3-

East)

4 (North, 

West, East, 

South)

5 (3-North, 

East, South)

Breakfast 1 (South) 1 (East)

Laundry 1 (East) 1 (South)

Closet/Pantry 1 (East) 2 (East) 2 (West, 

East) 1 (East)

Garage 1 (North) 1 (North) 1 (West) 1 (East) 1 (East) 1 (North)
17

6 Results of In-Service Environmental Conditions 

Measurements

The available recorded measurements for each home are presented by jobsite, floor level, and 

exterior wall orientations in various charts in this section. All results are reported as daily 

averages calculated based on the measurements recorded every half hour. Because the primary 

observation is the OSB MC level, RH and temperature plots are given for only the first-floor 

locations. The measurements recorded by the sensors installed in garage walls are included for 

each home. It should be noted that garages are constructed as unconditioned space in five of the 

six homes.

Based on visual observations of the siding in the spring of 2010, none of the six homes exhibited 

buckling to the degree that would be visible through the siding. The OSB MC increased from 

less than 6% to 11%, however, at the time of the site visit. The OSB MC ranged from 10% to 

25% at the time of first measurements after initial occupancy that started in January and 

February. Table 6 lists the calculated OSB panel expansions, which are based on these changes 

in MCs and the results of the linear expansion tests. OSB buckling potential is highest for Jobsite 

5 with installed panel gaps of 1⁄8 in. and a maximum calculated expansion of 5/16 in. Maximum 

potential panel expansions in the other homes all are in the range of the provided gaps; therefore,

buckling potential is low. In all homes, the MC started trending down in the spring months as the 

average daily temperature increased. These observed decreases in OSB MC ranged from about 

5% to as much as 20%.

Table 6. Potential OSB Panel Expansion

Jobsite OSB Mill Maximum Moisture 

Content Increasea

Maximum Calculated 

Panel Expansion (in.)

Vertical Edge Gap 

as Installed (in.)

1

Mill 1 16 3/16 0–3/16

Mill 2-A 14 1/16 -

2

Mill 3 14 1/16 0–1/8

Mill 2-B 13 3/16 -

3

Mill 4 8 1/16 0–5/32

Mill 2-B 6 1/16 -

4 Mill 3 - - 1/32–1/8

5

Mill 5 23 5/16 1/16–1/8

Mill 2-B 20 5/16 -

6 Mill 2-B 9 1/16 0–1/8

a. The maximum MC increase reported in this table is estimated relative to the MC at the time of the visit to allow for direct comparison of 

the calculated expansion with the gap measured at the time of the visit. It is likely that the OSB MC at the time of panel installation was 

lower and the overall change in MC was greater.
18

Based on the available data, Table 7 and Figure 17 through Figure 21 show the daily average 

OSB MCs for each jobsite. Figure 27 through Figure 51 show in-service home interior and wall 

cavity measurements of temperature, RH, DP, and a comparison of MC. In-service conditions 

are given for five of the six homes for the following performance periods (data for Jobsite 4 are

not available because of the lack of an agreement with the homeowner):

• Jobsite 1 – Late January 2010 to early December 2011

• Jobsite 2 – Late March 2010 to November 2011

• Jobsite 3 – Mid-March 2010 to mid-January 2011

• Jobsite 4 – No data available

• Jobsite 5 – Late January 2010 to November 2011

• Jobsite 6 – Mid-January 2010 to mid-September 2011.

Table 7. Summary Wall Cavity Moisture Characteristics for Latest Annual Period

Job

Site

Extended

Monitoring 

Period

Interior

Conditions Daysa

Peak OSB MC (Most Recent Year 

Data)

Annual Range

Cavity

MC

Temperature (T)

DP

Wall Orientation

N W E S

1 1/28/2010

12/11/11

Average RH

Maximum RH

Minimum RH

Average Temp

Winter RHb

33.2%

40.0%

22.4%

73.1°F

27.3%

365 15% 14% 9% 9%

Minimum MC 

Average MC 

Average T 

Average DP 

7%–9%

7%– 2%

62°F–68°F

40°F–48°F

2 3/22/2010

12/11/11

Average RH

Maximum RH

Minimum RH

Average Temp

Winter RHb

46.1

60.3

29.5

72.6°F

35.9%

355 17% 16% 30% 14%

Minimum MC 

Average MC

Average T 

Average DP 

8%–10%

9%–16%

57°F–60°F

47°F–50°F

3 3/16/2010

1/31/11

Average RH

Maximum RH

Minimum RH

Average Temp

Winter RHb

51.0

69.8

35.7

72.4°F

41.0%

304 14% 14% 17% 14%

Minimum MC 

Average MC 

Average T 

Average DP 

7%–10%

8%–11%

64°F–68°F

48°F–53°F

4 No Data Available

5 1/29/2010

12/11/11

Average RH

Maximum RH

Minimum RH

Average Temp

Winter RHb

52.4

68.8

35.2

71.8°F

44.7%

365 23% 18% 33% 16%

Minimum MC 

Average MC 

Average T 

Average DP 

9%–12%

12%–22%

55°F–58°F

48°F–52°F

6 1/13/2010

9/15/11

Average RH

Maximum RH

Minimum RH

Average Temp

Winter RHb

49.7

69.8

34.4

71.7°F

40.1%

365 13% n/a 12% 21%

Minimum MC 

Average MC 

Average T 

Average DP 

7%–9%

8%–12%

63°F–65°F

49°F–50°F

a In most recent annual measurement period

b Winter RH is the average interior RH for the period from December through March (if available)
19

Table 7 lists the initiation date of in-service condition monitoring and peak OSB MCs for each 

house. Also included in Table 7 is the range of interior RH over the most recent available annual 

monitoring period for each site. Daily average interior temperatures were approximately 70°F 

over the monitoring period for each house. The average wintertime interior RH is also included.

The trends in OSB MC demonstrate that during the initial stages of home occupancy as well as 

the subsequent winter period, MCs are elevated or elevating. As ambient temperatures increase 

in the spring, however, the MC in OSB panels decreases. This drying out of the panels is most 

accentuated during the first half of April, with a drop in OSB MC observed in all of the homes 

except one during this period. The MC of the OSB sheathing decreases to less than 12% over the 

summer for all homes.

Figure 17 through Figure 21 chart the change in the OSB sheathing MC for each test site based 

on daily averages. The data come from all wall cavities with available moisture sensor readings,

including the unconditioned garage wall cavity. The radial chart begins and ends at the 12 

o’clock position regardless of the total range of dates for the plot. In all cases, the starting point 

is within a few months of construction completion. The same data are included in Section 7.4,

but charted using a linear plot line.

As would be expected, the MC of the OSB sheathing increases in the winter months, peaking in 

late winter. In the colder months, and more generally in occupied homes with lower air

infiltration rates, the moisture drive is from the interior to the exterior. The moisture drive would 

include exfiltration and diffusion. In most cases, the drop-off to lower MC levels occurs in early 

spring through the summer and into the fall, when the cycle repeats. 
20

Figure 17. Jobsite 1 OSB MC, all available data

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0 Feb-10 Mar-10

Apr-10

May-10

Jun-10

Jul-10

Aug-10

Sep-10

Oct-10

Nov-10

Dec-10 Jan-11 Feb-11

Mar-11

Apr-11

May-11

Jun-11

Jul-11

Aug-11

Sep-11

Oct-11

Nov-11

Dec-11

2flSouth1-MC

1flEast1-MC

1flNorth1-MC

1flNorth2-MC

2flNorth1-MC

2flNorth2-MC

2flNorth3-MC

2flWest1-MC

1flNorthGarage-MC

1flNorth3-MC

1flSouth1-MC

2flEast1-MC

1flWest1-MC
21

Figure 18. Jobsite 2 OSB MC, all available data

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Mar-10 Apr-10

May-10

Jun-10

Jul-10

Aug-10

Sep-10

Oct-10

Nov-10

Dec-10

Jan-11 Feb-11 Mar-11

Apr-11

May-11

Jun-11

Jul-11

Aug-11

Sep-11

Oct-11

Nov-11

Dec-11

2flEastBR2-MC

2flEastbath-MC

1flEastkit-MC

1flWestMB-MC

1flEast2DR-MC

2flNorthBR4-MC

2flEastBR3-MC

2flSouthBR3-MC

1flNorthGarage-MC

1flEast1DR-MC

1flNorthDR-MC

2flEastclst-MC

1flSouthbrkfast-MC
22

Figure 19. Jobsite 3 OSB MC, all available data

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Mar-10

Apr-10

May-10

Jun-10

Jul-10

Aug-10

Sep-10

Oct-10

Nov-10

Dec-10

Jan-11

2flEastBR2

2flSouthBR3

1flWestKit

1flWestGarage

1flEastHbath

2flEastBR3clst

2flWestclst

1flEastFamR

1flNorthLVrm

2flNorthMB

1flSouthFamR

2flEastLoft

1flEastLVrm
23

Figure 20. Jobsite 5 OSB MC, all available data

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Feb-10

Mar-10

Apr-10

May-10

Jun-10

Jul-10

Aug-10

Sep-10

Oct-10

Nov-10

Dec-10

Jan-11 Feb-11

Mar-11

Apr-11

May-11

Jun-11

Jul-11

Aug-11

Sep-11

Oct-11

Nov-11

Dec-11

2flEastMBRbath-MC

1flWestFMR-MC

2flEastLndy-MC

1flEastGarage-MC

1flEastHbath-MC

1flEastMR-MC

2flWestBR3-MC

1flNorthFMR-MC

2flEastMBcl-MC

1flEastDR-MC

2flNorthBR2-MC

2flEastBR2-MC

2flSouthMBR-MC
24

Figure 21. Jobsite 6 OSB MC, all available data

As seen in the previous charts, Jobsites 2 and 5 show elevated MC in some wall cavities. The 

MC measurements indicate levels reaching to slightly greater than 30% in a few wall cavities. 

This level of MC suggests a fiber saturation point state of the OSB panels. 

A number of wall cavities in Jobsite 5 show elevated MC readings for an extended time period, 

lasting into the early summer when the MC readings drop off quickly. Figure 22 represents data 

for a 1-year period in a wall cavity comparing the MC to the cavity temperature. The cyclic 

nature of the MC is clearly shown as well as the relationship between the cavity temperature and 

the MC where the MC levels greater than 20% span both warm and cold seasons (and cavities). 

This result is unique among the five jobsites where data are available for an extended period.

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Jan-10

Feb-10

Mar-10

Apr-10

May-10

Jun-10

Jul-10

Aug-10

Sep-10

Oct-10

Dec-10 Nov-10

Jan-11

Feb-11

Mar-11

Apr-11

May-11

Jun-11

Jul-11

Aug-11

Sep-11

1flNorthGarage

1flNorthMB

1flNorth2MB

1flEastMB

1flNorthBR2

1flSouthBR3

1flSouthKit

1flSouthLaundry
25

Figure 22. Example of an elevated OSB MC in one wall section showing seasonal changes in MC

As RH increases in a wall cavity, the potential for condensation of water on the interior surface 

of OSB panels also increases. Figure 23 and Figure 24 are comparison plots for the test wall 

cavity temperature difference between the cavity temperature and the DP temperature for 

Jobsites 2 and 5. Negative values indicate a higher cavity DP than cavity air temperature near the 

OSB sheathing, resulting in the potential for condensation. Jobsite 2 has the most significant 

difference and Jobsite 5 has a much lesser degree of difference. The other jobsites have little or 

no calculated potential for condensation as measured.

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0

OSB Moisture Content, percent

Cavity Temperature, °F (January 2010 - November 2011)

Jobsite 5 OSB Moisture Content Relative to Cavity Temperature (1 year)

Dec '10-Mar '11

Mar '11 - Jun '11

Jun '11 - Sep '11

Sep '11 - Dec '11

Winter Spring

Fall

Summer
26

Figure 23. Jobsite 2 delta cavity temperature minus DP temperature (negative values indicate 

condensation potential)

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

Cavity Temperature - Dewpoint Temperature, °F

Interior (T-DP)

2flEastMBRbath (T-DP)

1flWestFMR (T-DP)

2flEastLndy (T-DP)

1flEastGarage (T-DP)

1flEastHbath (T-DP)

1flEastMR (T-DP)

2flWestBR3 (T-DP)

1flNorthFMR (T-DP)

2flEastMBcl (T-DP)

1flEastDR (T-DP)

2flNorthBR2 (T-DP)

2flEastBR2 (T-DP)

2flSouthMBR (T-DP)
27

Figure 24. Jobsite 5 delta cavity temperature minus DP temperature (negative values indicate 

condensation potential)

When evaluating the condensation potential (negative values for the air–DP temperatures) 

compared to the MC, the graphical results show an interesting relationship in which the higher 

levels of MC measured do not coincide directly with the calculated condensation potential (refer 

to Figure 25). In fact, the wall sections with the higher levels of MC appear to have lower overall 

instances of condensation potential.

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

Cavity Temperature-Dewpoint Temperature, °F

Interior T-DP 2flEastBR2 T-DP 2flEastbath T-DP 1flEastkit T-DP 1flWestMB T-DP

1flEast2DR T-DP 2flNorthBR4 T-DP 2flEastBR3 T-DP 2flSouthBR3 T-DP 1flNorthGarage T-DP

1flEast1DR T-DP 1flNorthDR T-DP 2flEastclst T-DP 1flSouthbrkfast T-DP
28

Figure 25. Jobsite 5 comparison of MC and DP

Furthermore, as shown in Figure 26, in this home where some cavities have higher levels of MC, 

the overall trends of all sections appear to track each other, although with different absolute 

levels of OSB MC. It does appear, however, that one or two cavities might have a source for air 

leakage (assumed from the interior), resulting in a much higher level of MC readings.

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

-15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0

OSB Moisture Content, percent

Delta Cavity Temperature and Dew Point Temperature, °F (negative values indicated condensation potential)

1flEastDR-MC

2flSouthMBR-MC

2flEastMBRbath-MC
29

Figure 26. Jobsite 5 MC comparison of all wall cavities

7 Data Comparisons

The next sections review the trends in the various moisture performance characteristics for the 

wall systems. All available data are plotted to indicate the trends from the construction 

completion through a period of occupancy. Refer to Table 1 for the individual characteristics of 

the homes for which wall cavity moisture data are available. The cavity moisture characteristics 

include the following:

• Air temperature near the OSB sheathing

• RH near the OSB sheathing

• DP temperature near the OSB sheathing

• MC of the OSB sheathing.

Other related characteristics include the indoor air temperature and RH as well as the ambient air 

temperature and RH (from a nearby weather station).

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Moisture Content, percent

2flEastMBRbath-MC 1flWestFMR-MC 2flEastLndy-MC 1flEastGarage-MC 1flEastHbath-MC

1flEastMR-MC 2flWestBR3-MC 1flNorthFMR-MC 2flEastMBcl-MC 1flEastDR-MC

2flNorthBR2-MC 2flEastBR2-MC 2flSouthMBR-MC
30

7.1 Cavity Temperatures

Figure 27 through Figure 31 show cavity temperatures near the OSB sheathing for each of the 

jobsites.

Figure 27. Jobsite 1 temperatures

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Temperature, °F

Temperature in Wall Cavity - Jobsite 1 (Climate Zone 4)

2flSouth1-T 1flEast1-T 1flNorth1-T 1flNorth2-T 2flNorth1-T

2flNorth2-T 2flNorth3-T 2flWest1-T 1flNorthGarage-T 1flNorth3-T

1flSouth1-T 2flEast1-T 1flWest1-T AmbientT Interior-T
31

Figure 28. Jobsite 2 temperatures

Figure 29. Jobsite 3 temperatures

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Temperature,°F

Temperature in Wall Cavity - Jobsite 2 (Climate Zone 5)

2flEastBR2-T 2flEastbath-T 1flEastkit-T 1flWestMB-T 1flEast2DR-T

2flNorthBR4-T 2flEastBR3-T 2flSouthBR3-T 1flNorthGarage-T 1flEast1DR-T

1flNorthDR-T 2flEastclst-T 1flSouthbrkfast-T AmbientT (°F) Interior-T

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

3/16/10 4/16/10 5/16/10 6/16/10 7/16/10 8/16/10 9/16/10 10/16/10 11/16/10 12/16/10 1/16/11

Temperature, °F

Temperature in Wall Cavity - Jobsite 3 (Climate Zone 5)

2flEastBR2-T 2flSouthBR3-T 1flWestKit-T 1flWestGarage-T 1flEastHbath-T

2flEastBR3clst-T 2flWestclst-T 1flEastFamR-T 1flNorthLVrm-T 2flNorthMB-T

1flSouthFamR-T 2flEastLoft-T 1flEastLVrm-T Indoor T Outdoor T
32

Figure 30. Jobsite 5 temperatures

Figure 31. Jobsite 6 temperatures

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Temperature, °F

Temperature in Wall Cavity - Jobsite 5 (Climate Zone 5)

2flEastMBRbath-T 1flWestFMR-T 2flEastLndy-T 1flEastGarage-T 1flEastHbath-T

1flEastMR-T 2flWestBR3-T 1flNorthFMR-T 2flEastMBcl-T 1flEastDR-T

2flNorthBR2-T 2flEastBR2-T 2flSouthMBR-T Indoor-T Outdoor T

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Temperature, °F

Temperature in Wall Cavity - Jobsite 6 (Climate Zone 5)

1flNorthGarage-T 1flNorthMB-T 1flNorth2MB-T 1flEastMB-T 1flNorthBR2-T

1flSouthBR3-T 1flSouthKit-T 1flSouthLaundry-T Indoor-T Outdoor T
33

7.2 Cavity Relative Humidity

Figure 32 through Figure 36 show cavity relative humidity near the OSB sheathing for each of 

the jobsites.

Figure 32. Jobsite 1 RH values

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Relative Humidity, percent

Relative Humidity in Wall Cavity - Jobsite 1 (Climate Zone 4)

2flSouth1-RH 1flEast1-RH 1flNorth1-RH 1flNorth2-RH 2flNorth1-RH

2flNorth2-RH 2flNorth3-RH 2flWest1-RH 1flNorthGarage-RH 1flNorth3-RH

1flSouth1-RH 2flEast1-RH 1flWest1-RH Outdoor RH Indoor RH
34

Figure 33. Jobsite 2 RH values

Figure 34. Jobsite 3 RH values

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Relative Humidity, percent

Relative Humidity in Wall Cavity - Jobsite 2 (Climate Zone 5)

2flEastBR2-RH 2flEastbath-RH 1flEastkit-RH 1flWestMB-RH 1flEast2DR-RH

2flNorthBR4-RH 2flEastBR3-RH 2flSouthBR3-RH 1flNorthGarage-RH 1flEast1DR-RH

1flNorthDR-RH 2flEastclst-RH 1flSouthbrkfast-RH Outdoor RH Indoor RH

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

3/16/10 4/16/10 5/16/10 6/16/10 7/16/10 8/16/10 9/16/10 10/16/10 11/16/10 12/16/10 1/16/11

Relative Humidity, percent

Relative Humidity in Wall Cavity - Jobsite 3 (Climate Zone 5)

2flEastBR2 RH 2flSouthBR3 RH 1flWestKit RH 1flWestGarage RH 1flEastHbath RH

2flEastBR3clst RH 2flWestclst RH 1flEastFamR RH 1flNorthLVrm RH 2flNorthMB RH

1flSouthFamR RH 2flEastLoft RH 1flEastLVrm RH Outdoor RH Indoor RH
35

Figure 35. Jobsite 5 RH values

Figure 36. Jobsite 6 RH values

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

60.0

65.0

70.0

75.0

80.0

85.0

90.0

95.0

100.0

Relative Humidity, percent

Relative Humidity in Wall Cavity - Jobsite 5 (Climate Zone 5)

2flEastMBRbath-RH 1flWestFMR-RH 2flEastLndy-RH 1flEastGarage-RH 1flEastHbath-RH

1flEastMR-RH 2flWestBR3-RH 1flNorthFMR-RH 2flEastMBcl-RH 1flEastDR-RH

2flNorthBR2-RH 2flEastBR2-RH 2flSouthMBR-RH Outdoor RH Indoor RH

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Relative Humidity, percent

Relative Humidity in Wall Cavity - Jobsite 6 (Climate Zone 5)

1flNorthGarage-RH 1flNorthMB-RH 1flNorth2MB-RH 1flEastMB-RH 1flNorthBR2-RH

1flSouthBR3-RH 1flSouthKit-RH 1flSouthLaundry-RH Indoor-RH Outdoor RH
36

7.3 Cavity Dew Point Temperatures

Figure 37 through Figure 41 show cavity DP temperatures near the OSB sheathing for each of 

the jobsites.

Figure 37. Jobsite 1 DP temperatures

0

10

20

30

40

50

60

70

80

90

Dew Point Temperature, °F

Dewpoint Temperature in Wall Cavity-Jobsite 1 (Climate Zone 4)

2flSouth1-DP 1flEast1-DP 1flNorth1-DP 1flNorth2-DP 2flNorth1-DP

2flNorth2-DP 2flNorth3-DP 2flWest1-DP 1flNorthGarage-DP 1flNorth3-DP

1flSouth1-DP 2flEast1-DP 1flWest1-DP Outdoor T Indoor T
37

Figure 38. Jobsite 2 DP temperatures

Figure 39. Jobsite 3 DP temperatures

0

10

20

30

40

50

60

70

80

90

Dew Point Temperature, °F

Dew Point in Wall Cavity - Jobsite 2 (Climate Zone 5)

2flEastBR2-DP 2flEastbath-DP 1flEastkit-DP 1flWestMB-DP 1flEast2DR-DP

2flNorthBR4-DP 2flEastBR3-DP 2flSouthBR3-DP 1flNorthGarage-DP 1flEast1DR-DP

1flNorthDR-DP 2flEastclst-DP 1flSouthbrkfast-DP Outdoor T

0

10

20

30

40

50

60

70

80

90

3/16/10 4/16/10 5/16/10 6/16/10 7/16/10 8/16/10 9/16/10 10/16/10 11/16/10 12/16/10 1/16/11

Dew Point Temperature, °F

Dew Point Temperature in Wall Cavity - Jobsite 3 (Climate Zone 5)

2flEastBR2-DP 2flSouthBR3-DP 1flWestKit-DP 1flWestGarage-DP 1flEastHbath-DP

2flEastBR3clst-DP 2flWestclst-DP 1flEastFamR-DP 1flNorthLVrm-DP 2flNorthMB-DP

1flSouthFamR-DP 2flEastLoft-DP 1flEastLVrm-DP Indoor-DP Outdoor T
38

Figure 40. Jobsite 5 DP temperatures

Figure 41. Jobsite 6 DP temperatures

0

10

20

30

40

50

60

70

80

90

Dew Point Temperature, °F

Dew Point Temperature in Wall Cavity - Jobsite 5 (Climate Zone 5)

2flEastMBRbath-DP 1flWestFMR-DP 2flEastLndy-DP 1flEastGarage-DP 1flEastHbath-DP

1flEastMR-DP 2flWestBR3-DP 1flNorthFMR-DP 2flEastMBcl-DP 1flEastDR-DP

2flNorthBR2-DP 2flEastBR2-DP 2flSouthMBR-DP Indoor-DP Outdoor T

0

10

20

30

40

50

60

70

80

90

Dew Point Temperature, °F

Dew Point Temperature in Wall Cavity - Jobsite 6 (Climate Zone 5)

1flNorthGarage-DP 1flNorthMB-DP 1flNorth2MB-DP 1flEastMB-DP 1flNorthBR2-DP

1flSouthBR3-DP 1flSouthKit-DP 1flSouthLaundry-DP Indoor-DP Outdoor T
39

7.4 Oriented Strand Board Moisture Content

Figure 42 through Figure 46 show the OSB MC for each of the jobsites.

Figure 42. Jobsite 1 MC

0

9

18

27

36

45

54

63

72

81

90

99

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Outdoor Temperature, °F

Moisture Content, percent

Moisture Content of OSB Sheathing - Jobsite 1 (Climate Zone 4)

2flSouth1-MC 1flEast1-MC 1flNorth1-MC 1flNorth2-MC 2flNorth1-MC

2flNorth2-MC 2flNorth3-MC 2flWest1-MC 1flNorthGarage-MC 1flNorth3-MC

1flSouth1-MC 2flEast1-MC 1flWest1-MC Outdoor T
40

Figure 43. Jobsite 2 MC

Figure 44. Jobsite 3 MC

0

9

18

27

36

45

54

63

72

81

90

99

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Ambient Outdoor Temperature, °F

Moisture Content, percent

Moisture Content of OSB Sheathing - Jobsite 2 (Climate Zone 5)

2flEastBR2-MC 2flEastbath-MC 1flEastkit-MC 1flWestMB-MC 1flEast2DR-MC

2flNorthBR4-MC 2flEastBR3-MC 2flSouthBR3-MC 1flNorthGarage-MC 1flEast1DR-MC

1flNorthDR-MC 2flEastclst-MC 1flSouthbrkfast-MC Outdoor T

0

9

18

27

36

45

54

63

72

81

90

99

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

3/16/10 4/16/10 5/16/10 6/16/10 7/16/10 8/16/10 9/16/10 10/16/10 11/16/10 12/16/10 1/16/11

Outdoor Temperature, °F

Moisture Content, percent

Moisture Content of OSB Sheathing - Jobsite 3 (Climate Zone 5)

2flEastBR2-MC 2flSouthBR3-MC 1flWestKit-MC 1flWestGarage-MC 1flEastHbath-MC

2flEastBR3clst-MC 2flWestclst-MC 1flEastFamR-MC 1flNorthLVrm-MC 2flNorthMB-MC

1flSouthFamR-MC 2flEastLoft-MC 1flEastLVrm-MC Outdoor T
41

Figure 45. Jobsite 5 MC

Figure 46. Jobsite 6 MC

0

9

18

27

36

45

54

63

72

81

90

99

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Outdoor Temperature, °F

Moisture Content, percent

Moisture Content of OSB Sheathing - Jobsite 5 (Climate Zone 5)

2flEastMBRbath-MC 1flWestFMR-MC 2flEastLndy-MC 1flEastGarage-MC 1flEastHbath-MC

1flEastMR-MC 2flWestBR3-MC 1flNorthFMR-MC 2flEastMBcl-MC 1flEastDR-MC

2flNorthBR2-MC 2flEastBR2-MC 2flSouthMBR-MC Outdoor T

0

9

18

27

36

45

54

63

72

81

90

99

0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

30.0

33.0

Outdoor Temperature, °F

Moisture Content, percent

Moisture Content of OSB Sheathing - Jobsite 6 (Climate Zone 5)

1flNorthGarage-MC 1flNorthMB-MC 1flNorth2MB-MC 1flEastMB-MC 1flNorthBR2-MC

1flSouthBR3-MC 1flSouthKit-MC 1flSouthLaundry-MC Outdoor T
42

7.5 Oriented Strand Board Moisture Content and Relative Humidity

Figure 47 through Figure 51 show the relationship between the OSB MC and the RH in the wall 

cavity for each of the jobsites. Wall cavities with higher level MCs are selected for the 

comparison. 

Figure 47. Jobsite 1 MC relative to humidity

5.0

10.0

15.0

20.0

25.0

30.0

35.0

20.0 30.0 40.0 50.0 60.0 70.0 80.0

Moisture Content, percent

Relative Humidity, percent (February 2010 - December 2011)

Moisture Content Relative to Cavity Humidity (Jobsite 1 - CZ4)

2flNorth2-MC

1flWest1-MC

1flNorthGarage-MC
43

Figure 48. Jobsite 2 MC relative to humidity

Figure 49. Jobsite 3 MC relative to humidity

5.0

10.0

15.0

20.0

25.0

30.0

35.0

30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0

Moisture Content, percent

Relative Humidity, percent (March 2010 - December 2011)

Moisture Content Relative to Cavity Humidity (Jobsite 2 - CZ5)

1flEast2DR-MC

1flEast1DR-MC

1flNorthDR-MC

5.0

10.0

15.0

20.0

25.0

30.0

35.0

30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0

OSB Moisture Content, percent

Cavity Relative Humidity, percent

Moisture Content Relative to Cavity Humidity - Jobsite 3 (CZ 5)

1flEastLVrm-MC

1flEastHbath-MC

1flWestGarage-MC
44

Figure 50. Jobsite 5 MC relative to humidity

Figure 51. Jobsite 6 MC relative to humidity

5.0

10.0

15.0

20.0

25.0

30.0

35.0

30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0

OSB Moisture Content, percent

Relative Humidity, percent (January 2010 - November 2011)

OSB Moisture Content Relative to Cavity Humidity (Jobsite 5 CZ5)

1flEastMR-MC

2flNorthBR2-MC

1flWestFMR-MC

2flEastMBRbath-MC

5.0

10.0

15.0

20.0

25.0

30.0

35.0

30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0

Moisture Content, percent

Relative Humidity, percent (Janaury 2010 - September 2011)

Moisture Content Relative to Cavity Humidity (Jobsite 6 - CZ5)

1flSouthLaundry-MC

1flNorthBR2-MC

1flNorthGarage-MC
45

8 Analysis Based on ASHRAE 160-2009

Before this study began, one of the home builders in Ohio reported that, while repairing walls 

with buckled OSB following the winter of 2009, a mold-like substance was often present on the 

interior face of the OSB panels. To investigate the potential for mold growth in the test homes 

monitored in this study, the observed environmental conditions of the wall cavity are evaluated 

using the threshold established by ASHRAE Standard 160-2009 “Criteria for Moisture-Control 

Design Analysis in Buildings” (ASHRAE, 2009). Standard 160 provides temperatures and 

associated RH ranges that minimize mold growth on the surfaces of components of building 

envelope assemblies (Table 8). 

Table 8. Standard 160 Condition Criteria Necessary to Minimize Mold Growth

Criteria Duration RH when Temperature is in Range

A 30 days <80% RH

B 7 days <98% RH 41°F < T < 104°F

C 24 hours <100% RH

The wall cavity temperatures and RH levels are evaluated according to these criteria for the 

homes, with results shown in Table 9.

Table 9. Wall Cavity Analysis of Standard 160 Criteria

Jobsite Days in 

Analysis

Range of Days in Which Criteria Exceeded in any Wall Cavity 

Number of Monitored Wall Cavities in Which Criteria Exceeded

Criteria A Criteria B Criteria C

1 655 0 0 0

2 600 8–157

11 of 13 test cavities 0 0

3 293 0 0 0

4 n/a n/a n/a n/a

5 653 88–324

12 of 13 test cavities

3–7

2 of 13 test cavities

6

1 of 13 test cavities

6 582 37

1 of 8 test cavities

2–50

2 of 8 test cavities 0

Note: n/a, data not available a For example, in Jobsite 2, criteria A was exceeded between 8 and 157 days in 11 of the 13 wall cavities under 

test

The Jobsite 5 home appears to have the greatest potential for moisture-related problems;

however, no problems have been reported. It is not known how the cyclic behavior of the wall 

cavity moisture characteristics is representative of long-term problems. Moreover, the ASHRAE 

160 criteria appear to be intended as a lower bound set to ensure that mold growth does not occur 

rather than as an indicator of a trigger at which mold growth does occur. Particularly, criterion A 
46

of 80% RH appears to be very conservative for wall cavities and would disqualify typical wall 

assemblies that have been used for many decades without reported problems. 

9 Summary 

This study documents construction methods and materials used by builders that experienced 

OSB buckling problems in previously constructed homes during the winter of 2008–2009. These

builders and newly constructed homes were selected for a more focused analysis of the wall 

cavity moisture conditions because the construction methods are very typical of building code 

practices and most met more stringent requirements of efficiency programs. The selected test 

homes all had air infiltration rates less than four ACH50, substantially lower than many new 

homes. Sensors installed in exterior wall cavities of six subject homes measure the cavity 

temperature and humidity and through a screw pin attachment, the MC of the wood structural 

sheathing. One sensor location within the interior of the home records indoor temperature and 

humidity. The data collected by the sensors provide objective moisture characteristics for the 

sheathing panels within the selected wall cavities over annual periods when the sensor receiver 

has Internet access. Samples of wall sheathing material were also taken from the construction 

sites and evaluated in terms of the moisture properties and expected expansion limits. 

Successful data collection for five homes ranged from 11 to 22 months (no data were available 

for one home). Over the first winter season of the study (November 2009 through May 2010), 

buckling of OSB wall sheathing was not observed in any of the six homes (the walls were 

visually inspected in April and May 2010). No subsequent reports indicated any continued 

problems with OSB buckling in these or other homes in the neighborhood. 

For an annual period, average cavity temperatures for all wall orientations were within 3°F in the 

same house and the average DP temperatures were within 5°F. In all homes, the MC started 

trending down in the spring (early to mid-April) as the average daily temperature increased. A 

typical observed drop of OSB MC ranged from 5% to 10%. Summertime sheathing MC in all 

monitored walls decreased to less than 12% regardless of the winter peak MC.

Periods of elevated MC in some wall sheathing panels were recorded in each of the homes. The 

OSB MC increased from less than 6% to 11% at the time of panel installation or jobsite visit to 

anywhere from 10% to more than 30% in some cases. In three of the homes, the OSB MC levels 

exceeded 15% for an extended period of time. In two of those three homes, MC peaked at more 

than 25%, with the highest measured MC at more than 30% (one sensor only). 

An analysis of the wall cavity conditions against a set of mold growth criteria based on 

temperature, RH, and their duration suggests that in two of the six homes there were periods 

when there was potential for mold growth based on the ASHRAE Standard 160. Of the three 

primary criteria (A, B, and C), criterion A was exceeded as much as half the time in one test 

cavity, criterion B was exceeded 10% of the time in one test cavity, and criterion C was 

exceeded 1% of the time in one test cavity. No further cavity investigation analysis is planned. 
47

10 Initial Results and Observations

The objectives of the study were to document cyclic wall cavity moisture characteristics;

document wall sheathing moisture characteristics in homes with substantially lower infiltration 

rates; and, with sufficient data, isolate the variables or a combination of variables that might

result in unsatisfactory moisture performance of standard acceptable wall system construction. 

The overall MC records, although somewhat limited, indicate the following for the structural 

sheathing:

• Post construction sheathing MC increase was common in all monitored homes.

• Periods of high MC (more than 15%) occurred at some time during the year for most of 

the homes.

• A cyclic nature to sheathing MC was common in all homes; however, the level of swing 

(amplitude) can be significantly different among homes in the same climate.

• Colder months had the highest levels of sheathing MC, as expected.

• Based on the limited data set, interior average RH appears not to be a good indicator of 

increased sheathing MC.

• The sample with the lowest interior average RH did correlate with the lowest average 

sheathing MC, as expected.

• Typical annual average interior RH levels were more than 45%.

• A calculation of the periods when there is condensation potential near the sheathing does 

indicate increased MC in the sheathing, but the peak level of elevated MC varies 

significantly.

As an unexpected result, analysis of the expansion of OSB panels based on the measured linear 

expansion properties and the measured peak MC levels suggests a significant potential for OSB 

buckling in the period following the construction process for one of the test homes (Jobsite 5). 

Based on calculations of expected linear expansion, the recommended gapping and panel 

expansion properties for the other four homes are adequate to prevent OSB buckling. Because

the wavy siding was not observed in Jobsite 5, it should be noted that limited amount of buckling 

would not show through vinyl siding because the siding strips are capable of spanning over 

minor imperfections in the wall sheathing. 

Analysis of a correlation between the results of blower door tests and the OSB MC in walls does 

not indicate a strong trend. To draw more definitive conclusions, this study needs to be expanded 

to include homes with a wider range of airtightness characteristics.

Among other observations, the walls with a southern orientation had the lowest sheathing MCs 

because of the higher cavity temperatures from the longer period of exposure to direct sunlight,

leading to higher drying potential.
48

11 Ongoing Moisture Research and Next Steps 

Results of this study will serve as a baseline for the next study (already underway), which 

focuses on the moisture performance of high R-value wall systems in energy efficient homes. 

The next phase of this research will look at wall systems upgraded to meet or exceed the 

minimum insulation levels and airtightness requirements of the 2012 IECC (ICC 2012). The 

focus of the study is on the performance of wall systems and, in particular, the moisture 

characteristics inside the wall cavity and in the wood sheathing. Furthermore, while this research 

will initially address new home construction, the goal is to address potential moisture issues in 

wall cavities of existing homes when insulation and air sealing improvements are made. 
49

References

ASHRAE. (2009). ANSI/ASHRAE Standard 160-2009, Criteria for Moisture-Control Design 

Analysis in Buildings. Atlanta, GA: ASHRAE.

DOE (2012a). “Building America Research for the American Home.” U.S. Department of 

Energy Building America Website. Accessed 

at: http://www1.eere.energy.gov/buildings/residential/ba_research.html

DOE (2012b). “Building America Guides and Case Studies.” U.S. Department of Energy 

Building America Website. Accessed 

at: http://www1.eere.energy.gov/buildings/residential/ba_guides_studies.html

DuPont (2007). DuPont Tyvek HomeWrap Physical Properties Data Sheet. DuPont. 2007. 

Accessed June 25, 2010:

http://www2.dupont.com/Tyvek_Weatherization/en_US/assets/downloads/K05031_HW_Prod_Prop.pdf.

ICC (2012). International Energy Conservation Code. Country Club Hills, IL: International 

Code Council.

James, W.L. (1988). Electric Moisture Meters for Wood. General Technical Report FPL-GTR-6. 

Madison, WI: Forest Products Laboratory.

National Institute of Standards and Technology. (2004). Voluntary Product Standard PS2-04, 

Performance Standard for Wood-Based Structural-Use Panels. United States Department of 

Commerce, Washington, DC: U.S. Government Printing Office.

The Dow Chemical Company. North America - Weathermate Plus - Housewrap. DOW Building 

Solutions. Accessed June 28, 2010:

http://www.dow.com/webapps/lit/litorder.asp?filepath=styrofoam/pdfs/noreg/179-

07168.pdf&amp;amp;pdf=true.
50

Bibliography

APA–The Engineered Wood Association. (2006). Moisture-Related Dimensional Stability. APA 

Technical Topics. Tacoma, WA: APA–The Engineered Wood Association.

Carll, C.; Highley, T. (1999). Decay of Wood and Wood-Based Products Above Ground in 

Buildings. Paper presented at the Third ASTM Symposium on Exterior Insulation and Finish 

Systems (EIFS): Innovations and Solutions to Industry Challenges, American Society for Testing 

and Materials, Volume 27, Issue 2. 

Drumheller, S. Craig; Carll, Charles G. 2010. Effect of Cladding Systems on Moisture 

Performance of Wood-Framed Walls in a Mixed-Humid Climate. Thermal performance of the 

Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010, 

Clearwater Beach, Florida [electronic resource]. [Atlanta, GA : American Society of Heating, 

Refrigerating and Air-Conditioning Engineers], 2010.

Haughton, L.; Murphy, C. (2003). Performance of OSB and Plywood Structural Panels, 

Interface, Raleigh, NC: RCI, Inc., http://www.rci-online.org/interface/2003-06-haughtonmurphy.pdf .
51

Appendix: Site Inspection Data Sheet

1. Site Location

Street City State

Zip Climate Zone Local Weather Station

Notes:

2. Dates of Construction/Weather

Date Rain data (total inches)

Foundation Start

Framing Start

Roof enclosed by

House enclosed by

Occupancy start on

3. House

Number of Stories (do not include basement)

Basement Yes No

Basement Conditioned/Unfinished Yes No N/A

Basement Finished Yes No N/A

Attached Garage Yes No

Garage Finished Yes No N/A

Ventilation System:

Code minimum (bathrooms, kitchen)

Whole-house ventilation

Yes No

Yes No

Project #:

(internal use only)
52

ERV

HRV

Whole-house humidifier

Whole-house dehumidifier

Yes No

Yes No

Yes No

Yes No

Heating System Type

Heating System:

Electric (HSPF)

Gas (AFUE)

Other

 _______________

 _______________

Cooling System Type

Cooling System:

Electric (SEER)

Other

 _______________

Ducts, duct location, duct insulation:

Hot Water System Type

Hot Water System:

Electric (EF)

Gas (EF)

Other

 ______ Tank Tankless

 ______ Tank Tankless

Energy Star House

Yes No

Other:
53

4. Wall framing and sheathing

WALL CONSTRUCTION 

Stick-built

Panelized on site

Panelized off site

FRAMING

2 x 4 walls

2 x 6 walls

Studs at 16” oc

Studs at 24” oc

Framing same all stories

Double To Plate

Single To Plate

Framing Species and Grade

Framing moisture content 

when being sheathed

Yes No 

 
54

OSB WALL SHEATHING

Panel Thickness

Panel Width

Panel Length

Panel Brand and Certification 

Agency

Panel Span Rating

Gap between Panels

Panel MC at installation

Continuously Sheathed Yes No 

TO BE COMPLETED IN 

THE LAB:

Linear expansion properties

Note: all measurements 

on a min of 5 panels per 

house
55

5. Thermal/Moisture/Air Barriers

WRB Brand

WRB Taped

WRB Perm Rating

Flashing Material

Flashing Details

Exterior Rigid Foam

Wall Cavity Insulation

Band Joist Insulation

Attic Insulation 

Basement Insulation

Raised Heel Truss

Attic Eave Baffles

Wall Vapor Retarder

Wall Paint

Air Sealing Details

Top Plates

Bottom Plates

Sill Plates

Rim Joists

Roof Heel

Recessed Lights

Shower/Tub

Garage

Yes No

Yes No

Yes No

Yes No
56

Basement

Blower Door Test Results

(if available)

Fill Out Energy Star Thermal 

Bypass Checklist as 

applicable and attach to this 

checklist

Complete N/A
DOE/GO-102012-3628 ▪ December 2012

Printed with a renewable-source ink on paper containing at 

least 50% wastepaper, including 10% post-consumer waste.