SPECIAL REPORT 97-7

Shallow Insulated Foundation

at Galena, Alaska

A Case Study

Lawrence S. Danyluk March 1997
Abstract: A 2000-ft2 addition to an aircraft control

tower was constructed at Galena, Alaska, during the

summer of 1990. Because of limited resources, a

shallow insulated foundation (SIF) was specified

instead of a traditional foundation (one in which the

bottom of the footing is placed lower than the anticipated depth of frost penetration). An SIF design allows

How to get copies of CRREL technical publications:

Department of Defense personnel and contractors may order reports through the Defense Technical Information Center:

DTIC-BR SUITE 0944

8725 JOHN J KINGMAN RD

FT BELVOIR VA 22060-6218

Telephone 1 800 225 3842

E-mail help@dtic.mil

msorders@dtic.mil

WWW http://www.dtic.dla.mil/

All others may order reports through the National Technical Information Service:

NTIS

5285 PORT ROYAL RD

SPRINGFIELD VA 22161

Telephone 1 703 487 4650

1 703 487 4639 (TDD for the hearing-impaired)

E-mail orders@ntis.fedworld.gov

WWW http://www.fedworld.gov/ntis/ntishome.html

A complete list of all CRREL technical publications is available from:

USACRREL (CECRL-LP)

72 LYME RD

HANOVER NH 03755-1290

Telephone 1 603 646 4338

E-mail techpubs@crrel.usace.army.mil

For information on all aspects of the Cold Regions Research and Engineering Laboratory, visit our World Wide Web site:

http://www.crrel.usace.army.mil

the footing to be placed at a much shallower depth by

incorporating the use of strategically placed insulation

around the foundation. The insulation utilizes heat

from the building and surrounding soil, redirects it to

the area around the foundation, and thus reduces the

frost penetration.
Special Report 97-7

Shallow Insulated Foundation

at Galena, Alaska

A Case Study

Lawrence S. Danyluk March 1997

Prepared for

OFFICE OF THE CHIEF OF ENGINEERS

Approved for public release; distribution is unlimited.

US Army Corps

of Engineers

Cold Regions Research &

Engineering Laboratory

®
PREFACE

This report was prepared by Lawrence S. Danyluk, Research Civil Engineer, Civil Engineering Research Division, Research and Engineering Directorate, U.S. Army Cold

Regions Research and Engineering Laboratory (CRREL), Hanover, New Hampshire.

The study was funded under DA project AT42-CA-D05, Geotechnical Structures in Cold

Regions.

The author acknowledges the efforts of the 5099th Civil Engineering Squadron and in

particular Lee Ames for assisting in the construction and instrumentation of the foundation test site. The author also thanks Dr. Stephen Ketcham and Charles Korhonen of

CRREL for their valuable critical review of this report.

This publication reflects the personal views of the authors and does not suggest or

reflect the policy, practices, programs, or doctrine of the U.S. Army or Government of the

United States. The contents of this report are not to be used for advertising or promotional

purposes. Citation of brand names does not constitute an official endorsement or approval

of the use of such commercial products.

ii
iii

CONTENTS

Preface .......................................................................................................................................... ii

Introduction ................................................................................................................................. 1

Site characterizations ................................................................................................................. 1

Background ................................................................................................................................. 2

Design considerations................................................................................................................ 3

Foundation design ..................................................................................................................... 4

Instrumentation .......................................................................................................................... 5

Foundation construction ........................................................................................................... 5

Results and discussion .............................................................................................................. 6

Conclusions ................................................................................................................................. 10

Literature cited ............................................................................................................................ 12

Abstract ........................................................................................................................................ 13

ILLUSTRATIONS

Figure

1. Location map, Galena, Alaska........................................................................................... 1

2. Galena Airport, general vicinity plan .............................................................................. 2

3. Heat flow lines around a shallow insulated foundation .............................................. 3

4. Foundation plan and cross section ................................................................................... 4

5. Location of temperature sensors....................................................................................... 5

6. Excavation of foundation ................................................................................................... 6

7. Floor insulation.................................................................................................................... 6

8. Ground insulation, temperature sensor .......................................................................... 6

9. Ground and stem wall insulation ..................................................................................... 6

10. Existing control tower and complete addition ............................................................... 6

11. Average daily air temperatures ........................................................................................ 7

12. Isotherm for the winter of 1990–91................................................................................... 8

13. Isotherm for the winter of 1991–92................................................................................... 8

14. Isotherm for the winter of 1992–93................................................................................... 8

15. Temperatures above and below horizontal ground insulation ................................... 9

16. Temperatures under floor insulation and at toe of footing .......................................... 9

17. Yearly temperatures at toe of footing............................................................................... 10

18. Yearly temperatures under horizontal ground insulation ........................................... 10

19. Temperatures 1990–91 vs. 1992–93 ................................................................................... 11

20. Temperatures taken 2 ft below grade............................................................................... 11
INTRODUCTION

A 2000-ft2 addition to an aircraft control tower

was constructed at Galena, Alaska, during the

summer of 1990. Because of limited resources, a

shallow insulated foundation (SIF) was specified

instead of a traditional foundation (one in which

the bottom of the footing is placed lower than the

anticipated depth of frost penetration). In this

case, a 20-in.-deep foundation was constructed

instead of one at 12 ft. An SIF design allows the

footing to be placed at a much shallower depth

by incorporating the use of strategically placed

insulation around the foundation. The insulation

utilizes heat from the building and surrounding

soil, redirects it to the area around the foundation, and thus reduces the frost penetration.

The Scandinavian countries routinely use

insulation around shallow foundations to protect them from frost damage (Farouki 1992);

however, the use of the SIF system in this country

is still new and somewhat limited. Most buildings codes require footings to be placed below

the expected depth of frost. There is currently an

effort to change the codes to allow for the use

and implementation of SIFs.

This report will first describe the design and

construction of an SIF in an extremely remote

and harsh environment. It will then describe the

performance of the foundation during the following three winters.

SITE CHARACTERIZATIONS

Galena is a small village located in west central Alaska. It is approximately 350 miles northwest of Anchorage and 275 miles west of Fairbanks along the banks of the Yukon River (Fig. 1).

Adjacent to the village is an airfield and associated support buildings used by the Air Force for

aircraft out of Elmendorf AFB. The Air Force is

responsible for the operation and maintenance of

the airport and associated facilities. The only

Shallow Insulated Foundation at Galena, Alaska

A Case Study

LAWRENCE S. DANYLUK

A r c t i c C i r c l e

160°

180°

68°

60°

52°

140°

Y u k o n

R i v e r

Y u k o

n

R i v e r

Barrow

Fairbanks

Galena

Anchorage

0

0 300

250

Statute Miles

Kilometers

Figure 1. Location map, Galena, Alaska.
practical year-round access to the area is by air

transport. River boats or barges may be used

when the river is ice-free.

Galena is located on the flood plain in a broad

basin more than 30 miles wide bordered by hills

and mountains up to 2000 ft high. The basin is

crossed by the Yukon River, whose elevation is

approximately 100 ft (mean sea level) at low

water at Galena, and by the Yukon’s large north

tributary, the Koyukuk River. Both rivers are bordered by a flood plain that is up to 10 miles wide

and covered by many elongated channel lakes,

sloughs, and swamps. The rest of the basin

between the flood plain and the bordering bedrock consists of alluvial terraces.

Galena is within the discontinuous permafrost

zone although there is no known permafrost on

the base. The water table varies with the elevation

of the Yukon River, but generally is 8–10 ft below

the ground surface. There have been times during

spring breakup when the elevation of the river

actually has become higher than that of the airport. However, the water table at the base seems

to rise no more than 2–4 ft below the surface. Figure 2 shows how the base is surrounded by a system of levees.

The soils at the site are generally river deposits

of sands and gravels. A typical profile obtained

from soil borings in the immediate area is shown

below:

0.0–2.5 ft Sandy gravel;

2.5–7.0 ft Gravelly sand, 2–4% fines;

7.0–9.0 ft Silt;

9.0–22.0 ft Silty gravelly sand, 3–15% fines;

22.0–47.5 ft Sand.

The weather at Galena is typical of the sheltered continental interior of Alaska. This type of

climate is characterized by quite cold winters

2

   yyyy yy yyy

Y u k o n

R i v e r

0 2000 ft

N

Road

Hanger

Asphalt Runway (7500 ft × 350 ft)

Dike

Dike

Airport Control Tower

Figure 2. Galena Airport, general vicinity plan.

with relatively little precipitation and summers

that are considered relatively warm for Alaska.

Winter temperatures fall well below zero, at times

reaching –60°F for periods of weeks. There are

usually several thaw periods of one to two days

each per winter. Temperatures rise to 80°F for

approximately two weeks during the summer.

The mean annual temperature is approximately

25°F. The design and average air freezing indexes

(FI) are 6000 and 5500 °F-days, respectively.

BACKGROUND

Engineers at the Air Force’s 5099th Civil Engineering Operations Squadron were tasked to provide a new structure for the weather station at

Galena. It was decided that the most logical place

would be at the airport, adjacent to the aircraft

control tower (Fig. 2). Because of budget constraints and the remoteness of the site, the building had to be designed such that it required shipping the minimal amount of material and equipment. For example, cement had to be airlifted to

the site in 94-lb bags; the concrete was then made

on site using a small motorized mixer. By minimizing the amount of concrete needed for the

project, the shipping, labor, and construction

costs, as well as the time required to make the

concrete, were reduced.

The designers were particularly concerned

about the foundation’s stability. Because the

addition was to be attached to the control tower,

there could be no differential movement between

the two. This would have required a conventional

foundation depth of 12 ft (estimated frost depth

in the area), similar to the control tower. At the

same time it would have required large machinery to dig the excavation, additional material to

shore up the sides of the excavation, and large

quantities of concrete for the footings, none of
which were available or affordable to the project.

The designers decided the concept of an SIF

would be the most practical solution to this

unique project.

DESIGN CONSIDERATIONS

For a typical SIF structure with slab-on-grade

construction, about 10% of the heat loss from inside the building is through the floor (Torgersen

1976). The actual amount varies according to the

effectiveness of the insulation in the rest of the

structure. The heat loss through the floor passes

through the ground below and rises toward the

outside air by means of an approximately semicircular path. The effect is to reduce the frost

depth near the foundation compared with the

frost depth in undisturbed ground. The heat flow

from a floor will take the path with the least

amount of thermal resistance, whether it be the

connection between the floor and foundation

wall (where a cold bridge could form), through

the foundation wall, or through the soil under the

floor and foundation.

In an SIF structure, the insulation must be

placed so that the majority of the heat loss

through the floor is guided to the underside of

the foundation. This can be done with floor, wall,

and ground insulation, as shown in Figure 3. The

type of insulation to use, how much, and where

to place it depend on many variables, including

(but not limited to) climate, soil type, moisture

conditions, building type and use, snow conditions, and exposure.

The starting point in an SIF design is to select

the necessary floor insulation. If the insulation

has a low thermal resistance, the heat loss across

it is large. The floor’s temperature is reduced, but

the frost boundary does not advance very deeply

at the foundation wall because of the large heat

flow contribution from the floor. On the other

hand, if the floor insulation has a high thermal

resistance, heat loss is restricted and thereby

maintains higher floor surface temperatures. As

a result, the frost boundary advances deeper

down the foundation wall and thus the foundation depth must increase. A balance must be established that results in both a comfortable floor

surface temperature and acceptable frost penetration depth.

The next step is to determine the requirements

for foundation wall insulation. Great care should

be taken to ensure interruption of all possible

cold bridges at the junction of the floor, the foundation wall, and the outer wall. Insulation placed

on the outside of the foundation wall requires

protection above grade from physical and ultraviolet radiation damage. Insulation installed on

the inside of the foundation wall does not require

this protection; however, with inside insulation

there have been cases of the outside foundation

wall becoming cold enough for the soil to adfreeze to it. If this outside soil then heaves, the

foundation can be lifted or jacked. Furthermore,

walls with inside insulation are more susceptible

to cold bridges and in some cases are subject to

loads from the floor or foundation, and thus require an insulation with a higher compressive

strength.

Insulation placed horizontally outside the

foundation is called ground or wing insulation

and is usually used only in colder climates with a

freezing index greater than 2250 °F-days (NBI

1986). The horizontal insulation inhibits the

release of the soil heat, which is stored in the soil

during the summer half of the year and is available to retard the downward advance of frost. For

maximum thermal efficiency, ground insulation

should be placed as near the ground surface as

possible (Farouki 1992). Because of the threedimensional heat-loss effect at corners, additional ground insulation is usually required. However, this could result in damage by inadvertent

digging or vegetation. Care must be taken to protect the insulation from physical and moisturerelated damage. In areas where the insulation

may experience loading, an insulation with sufficient compressive strength must be specified.

The three most common types of insulations

used in SIFs are mineral wool, expanded or molded polystyrene (EPS), and extruded polystyrene

3

Freezing

Effect

Heat Flow

Cooling of

Unfrozen Soil

32°F Isotherm

Freezing Heat

Released

Cooling of

Frozen Soil

Figure 3. Heat flow lines around a shallow insulated

foundation.
(XEPS). Other materials, such as closed-cell urethane, lightweight clinker, or wood chips, may

be used as insulators. Extruded polystyrene is

usually recommended in this country when

the insulation is to be buried. Its closed-cell

design inhibits moisture absorption, thus

enabling its thermal resistance to remain

high. Expanded polystyrene may be used

if precautions are taken to limit its exposure to moisture.

FOUNDATION DESIGN

At the time of the weather station’s

design, there were no publications available in this country to assist in an SIF

design. The designers resorted to using

the Norwegian Building Research Institute’s (NBI 1986) charts, graphs, and

building details as a guide to assist in the

design. It was found, however, that the

NBI publications addressed climates

only as severe as 4500 °F-days. NBI’s figures were projected out to meet the conditions

expected at Galena by using a simple leastsquares regression analysis.

The final foundation plan is shown in Figure

4a and the cross section in Figure 4b. The bottom

of the footing is approximately 20 in. below

grade. The insulation chosen was an extruded

polystyrene with a density of 2.0 pcf, a vertical

compressive strength of 30 psi, a thermal resistivity (R-value) of 4.9 ft2-hr-°F/Btu-in., and a thermal conductivity (k-value) of 0.204 Btu/hr-in.-°F.

4

 





 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 







yyy yyyyy

yyyyyyy

yyyyyyyyy

yy yyyyyyyyy

yy yyyyyyyyyyy

yy yyyyyyyyyyyyy

yy yyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyyyy

yy yyyyyyyyyyyyyyy

yy yyyyyyyyyyyyy

yy yyyyyyyyyyy

yy yyyyyyyyy

yy yyyyyyy

yyyyyyy

yyyyy

yyyy

 





Existing Foundation

Ground Insulation

New Foundation

6 ft

35.67 ft47.67 ft

28 ft

6 ft

35.67 ft

28 ft

Existing Foundation

a. Foundation plan.

The wall and ground insulations are 4-in.-thick

XEPS. It was determined that the ground insulation had to extend 48 in. along the side of the

building and 72 in. at the corners. For ease of construction and added safety, all of the ground insulation was installed out 72 in. from the building.

Design calculations required that the floor insulation be 2 in. thick throughout the structure, except

for a 3-ft strip along the outer wall that required a

4-in.-thick layer. However, the floor was constructed using only 2 in. of insulation throughout.

Figure 4. Foundation plan and

cross section.

b. Foundation cross section.

     





             

 @@@@@@@@@@@@@@@@@@@@@@@@@  ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ  @@@@@@@@@@@@@@@@@@@@@@@@@  ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ

 



 

 

    

     

    

@@@@ @@@@

@

@@@@@@@@ @@@@@@@@

@@@@@@@@@@@ @@@@

@@@@@@@@@@@@ @@@@ @@@@@@@@@@@@ @@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@@ @@@@@@@ @@@@@@@@@@@@ @@@@@ @@@@@@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@ @@@@@@@@@ @@@@@@@ @@@@@ @@@@

 



 

 

    

     

    

ÀÀÀÀ ÀÀÀÀ

À

ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀ

 



 

 

    

     

    

@@@@ @@@@

@

@@@@@@@@ @@@@@@@@

@@@@@@@@@@@ @@@@

@@@@@@@@@@@@ @@@@ @@@@@@@@@@@@ @@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@@ @@@@@@@ @@@@@@@@@@@@ @@@@@ @@@@@@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@ @@@@@@@@@ @@@@@@@ @@@@@ @@@@

 



 

 

    

     

    

ÀÀÀÀ ÀÀÀÀ

À

ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀ

 



 

 

    

     

    

@@@@ @@@@

@

@@@@@@@@ @@@@@@@@

@@@@@@@@@@@ @@@@

@@@@@@@@@@@@ @@@@ @@@@@@@@@@@@ @@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@@ @@@@@@@ @@@@@@@@@@@@ @@@@@ @@@@@@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@ @@@@@@@@@ @@@@@@@ @@@@@ @@@@

 



 

 

    

     

    

ÀÀÀÀ ÀÀÀÀ

À

ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀ

 



 

 

    

     

    

@@@@ @@@@

@

@@@@@@@@ @@@@@@@@

@@@@@@@@@@@ @@@@

@@@@@@@@@@@@ @@@@ @@@@@@@@@@@@ @@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@@ @@@@@@@ @@@@@@@@@@@@ @@@@@ @@@@@@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@ @@@@@@@@@ @@@@@@@ @@@@@ @@@@

 



 

 

    

     

    

ÀÀÀÀ ÀÀÀÀ

À

ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀ

 



 

 

    

     

    

@@@@ @@@@

@

@@@@@@@@ @@@@@@@@

@@@@@@@@@@@ @@@@

@@@@@@@@@@@@ @@@@ @@@@@@@@@@@@ @@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@@ @@@@@@@ @@@@@@@@@@@@ @@@@@ @@@@@@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@ @@@@@@@@@ @@@@@@@ @@@@@ @@@@

 



 

 

    

     

    

ÀÀÀÀ ÀÀÀÀ

À

ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀ

 



 

 

    

     

    

@@@@ @@@@

@

@@@@@@@@ @@@@@@@@

@@@@@@@@@@@ @@@@

@@@@@@@@@@@@ @@@@ @@@@@@@@@@@@ @@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@@ @@@@@@@ @@@@@@@@@@@@ @@@@@ @@@@@@@@@@@@ @@@@@@@@@@@@

@@@@@@@@@@@ @@@@@@@@@ @@@@@@@ @@@@@ @@@@

 



 

 

    

     

    

ÀÀÀÀ ÀÀÀÀ

À

ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀÀÀ ÀÀÀÀÀÀÀ ÀÀÀÀÀ ÀÀÀÀ

 

1.5 ft

0.67 ft

1 ft

Native Soil

NFS Drainage Layer

1.5 ft

0.67 ft

1 ft

5% Slope Finished Grade

8 Mil Polyethylene

4 in. Extruded

Polystyrene

Insulation

2 in. Extruded

Polystyrene

Insulation

6 ft 



 

 

y

yyy yyyyy

yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyy



Existing Foundation
Although the floor’s surface temperature would

be slightly lower at the outer edge, the design

strategy was to use the additional heat lost to the

subgrade to keep the footing frost-free.

Also note in Figure 4b the non-frost-susceptible

(NFS) drainage layer, perforated drain tile, and 8-

mil plastic film. These are specified to minimize

any moisture from coming in contact with the

insulation or foundation.

INSTRUMENTATION

Temperature sensors were installed along the

east side of the addition because it was thought

that the coldest ground temperatures would occur

there. The building profile is narrow along this

side and thus the heat loss from the building to the

ground is minimal. Also, the east side of the addition is kept free of snow for vehicle parking.

During the spring of 1990, 64 temperature sensors were installed to get a temperature profile of

the SIF. After a winter’s worth of data, it was obvious that additional sensors would be needed because the frost line was penetrating deeper than

anticipated and more detailed temperature information was needed under the ground insulation.

Sixteen additional sensors were installed during

the summer of 1991. The location of all sensors can

be seen in Figure 5.

Because of scheduling conflicts, temperature

sensors were not installed above the slab insulation or within the floor itself. This would have

been useful in determining the comfort level of the

floor. Comments on comfort were verbally provided by the weather technicians using the facility.

The temperature sensors used at the addition

were type-T, copper-constantan thermocouples.

The sensor wires were crimped together at the end

and coated with an epoxy. A cap was then heatshrunk around the sensor to make it completely

waterproof. The thermocouples were connected

to low-resistance switches located inside the addition and read using a digital thermometer. The

overall accuracy with the type-T sensors is

approximately ±0.8°F.

The temperature strings were read once a week

by the weather technicians. Because it is a firstorder weather station, meteorological data were

available.

FOUNDATION CONSTRUCTION

Construction on the foundation began in June

1990 and the project was completed in December

1990. No precise length of time can be attributed

to the foundation construction phase because the

crew was continually pulled from the site to work

on other projects. However, conversations with

the site foreman revealed that a substantial

amount of time was saved: he estimated the SIF

took 1–2 weeks to complete whereas a conventional foundation would have taken 3–4 weeks.

Construction of the SIF is similar to a conventional foundation and is very straightforward.

Figure 6 depicts the excavation along the east side

of the addition. The laborers are leveling the bottom of the excavation; the footings will be placed

at this elevation. In Figure 7 the footing and stem

wall have been poured and the excavation has

been backfilled to the top of the footing. (The man

5



    

@

@@@ @@@@ @@@@@@@@@@@@ @@@@ @@



    

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



    

@

@@@ @@@@ @@@@@@@@@@@@ @@@@ @@



    

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



    

@

@@@ @@@@ @@@@@@@@@@@@ @@@@ @@



    

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



    

@

@@@ @@@@ @@@@@@@@@@@@ @@@@ @@



    

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



    

@

@@@ @@@@ @@@@@@@@@@@@ @@@@ @@



    

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



    

@

@@@ @@@@ @@@@@@@@@@@@ @@@@ @@



    

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀÀÀÀÀÀÀ ÀÀÀÀ ÀÀ

0

0

2

4

6

8

10

12

14

2 4 6 8 10 12

Distance (ft)

Depth (ft)

14 16 18 20 22 24

A40

A2

B25

A31 B13 B2

B3

B4

B5

B6

B7

B8

B9

B10

B11

B12

B40

B39

B14

B15

B16

B17

B18

B19

B20

B21

B22

B23

B24

B38

B37

A23

A24

A25

A26

A21

A13

A14

A22

A15

B34

B33

A28

A29

A30

A16

A17

A18

A19

A20

A39

A38

B26

B27

B28

B29

B30

B31

B32

A3

A3

A3

A3

A4

A5

A6

A7

A8

A9

A10

A11

A12

A3 A1

A33 B35 A32 B1

A27

B36

A3 A1

A33

B35 A32 B1

A27

B36

Concrete

Insulation

Figure 5. Location of temperature sensors.
6

Figure 6. Excavation of foundation.

Figure 7. Floor insulation.

Figure 8. Ground insulation, temperature sensor.

Figure 9. Ground and stem wall insulation.

Figure 10. Existing control tower and complete addition.

on the outside of the wall is standing on top of the

footing.) The laborer inside the foundation is

placing the floor insulation. Note that the surface

was prepared so the insulation lies flat and thus is

less vulnerable to breakage. A plastic 8-mil film

was placed over the insulation prior to the floor

being poured. Figures 8 and 9 show the installation of the ground insulation. In Figure 8 the

ground insulation is being placed horizontally on

top of the footing and the plastic film placed over

it. The wire that the laborer is holding is a temperature sensor that will be installed below the insulation. Figure 9 shows the stem wall insulation in

place and backfill placed over the ground insulation. Figure 10 is the existing control tower and

the complete addition.

RESULTS AND DISCUSSION

Temperatures were recorded for the winters of

1990–91, 1991–92, and 1992–93. During the early

part of the first winter the addition was still

under construction; it was only occasionally

heated until the addition was completed and

occupied in December. The second winter there

were numerous personnel changes at the weather

station and thus thermocouple readings were
7

sporadic. During the final year the readings were

recorded regularly on an established schedule.

Freezing indices for the three winters were 5600,

6100, and 5500 °F-days, respectively.

All three winters were at least as cold as the

average of 5500 °F-days, with two being 2% and

11% colder than average. The 1991–92 winter was

2% colder than the design index of 6000 °F-days.

Average daily air temperatures for the three winters are shown in Figure 11.

Figures 12–14 illustrate the 32°F isotherms for

various dates throughout the winter. The isotherms in Figure 12 are truncated because the

frost penetrated deeper than the sensors that

were installed at that time. Additional sensors

were placed deeper the following winter, and

sensors were also installed to provide a more detailed temperature regime under the insulation. It

is apparent from the figures that at no time during the monitoring period did the 32°F isotherm

threaten the bottom of the footing. As expected,

the depth of frost on the far right side of the figures (areas assumed not to be influenced by heat

loss from the foundation, i.e., control area) were

deeper during the colder 1991–92 winter than the

others. However, it seems that the freezing front

never gets closer than approximately 6–12 in. out

Figure 11. Average daily air temperatures.

60

40

20

0

–20

–40

–60

60

40

20

0

–20

–40

–60

60

40

20

0

–20

–40

–60 10 10 10 20 20 20 10 20 10 20 10 20 10 20 10 20 10 20

Sep Oct Nov Dec Jan Feb Mar Apr May

Air Temperature (°F)

1990-91

1991-92

1992-93

from the bottom corner of the footing regardless

of the frost load. It is also interesting to note that

the maximum frost penetration next to the footing occurs in early to mid February, whereas in

the control area this occurs in the more traditional

time frame of mid to late March.

Figure 15 shows the temperature difference

above and below the horizontal insulation approximately 3 ft out from the footing. The figure

illustrates the effectiveness of the insulation to retard heat loss from the foundation and surrounding ground. Even with winter temperatures of

–10°F above the insulation, the temperature

under the insulation seems to hover around 30°F,

with periods where it may vary by a couple of

degrees, but never falls lower than 24°F.

There are two areas where temperatures are

critical around an SIF: the first is under the toe of

the footing (sensor B25) and the second is under

the floor slab (sensors A1 and A3). Figure 16

shows that the temperature never gets lower than

34°F at the toe of the footing. It also shows that

the temperature below the floor insulation gets

below 37°F for only a short period of time. As expected, temperatures under the floor insulation

at the outside edge of the slab (sensor A1) are

lower than those at the center (sensor A3). Unfor-
8

tunately, a temperature sensor was not placed

above the floor insulation. This would have given

an indication of the comfort level of the floor;

however, technicians working in the addition

have commented that the floor never felt cold

even when the outside temperature was –60°F.

Temperatures at the toe of the footing (B25) and

midway under the horizontal ground insulation

(A27) are shown in Figures 17 and 18 for the three

years of the study. Temperatures for the 1991–92

year are generally lower than the other two years.

This coincides with the magnitudes of the freezing





 



  



  

@

@@@

@@@@ @@@@

@@@@

@@@@ @@@@ @@@@@@

@@@

@@@ @@@@ @@





 



  



  

À

ÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀ

ÀÀÀ ÀÀÀÀ ÀÀ





 



  



  

@

@@@

@@@@ @@@@

@@@@

@@@@ @@@@ @@@@@@

@@@

@@@ @@@@ @@





 



  



  

À

ÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀ

ÀÀÀ ÀÀÀÀ ÀÀ





 



  



  

@

@@@

@@@@ @@@@

@@@@

@@@@ @@@@ @@@@@@

@@@

@@@ @@@@ @@





 



  



  

À

ÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀ

ÀÀÀ ÀÀÀÀ ÀÀ





 



  



  

@

@@@

@@@@ @@@@

@@@@

@@@@ @@@@ @@@@@@

@@@

@@@ @@@@ @@





 



  



  

À

ÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀ

ÀÀÀ ÀÀÀÀ ÀÀ





 



  



  

@

@@@

@@@@ @@@@

@@@@

@@@@ @@@@ @@@@@@

@@@

@@@ @@@@ @@





 



  



  

À

ÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀ

ÀÀÀ ÀÀÀÀ ÀÀ





 



  



  

@

@@@

@@@@ @@@@

@@@@

@@@@ @@@@ @@@@@@

@@@

@@@ @@@@ @@





 



  



  

À

ÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀ

ÀÀÀ ÀÀÀÀ ÀÀ



0

0

2

4

6

8

10

12

14

2 4 6 8 10 12

Distance (ft)

Depth (ft)

14 16 18 20 22 24

Concrete

Insulation

–––––––––––––––––– 1991-92

11 Nov '91

03 Dec '91

14 Jan '92

18 Feb '92

10 Mar '92

Figure 13. Isotherm (32°F) for the winter of 1991–92.



  

 

   

  

@

@@@ @@@@ @@@@

@@@@ @@@@@@@@

@@@@ @@@@ @@@@ @@@@@@

@@@@@@ @@@@ @@



  

 

   

  

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



  

 

   

  

@

@@@ @@@@ @@@@

@@@@ @@@@@@@@

@@@@ @@@@ @@@@ @@@@@@

@@@@@@ @@@@ @@



  

 

   

  

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



  

 

   

  

@

@@@ @@@@ @@@@

@@@@ @@@@@@@@

@@@@ @@@@ @@@@ @@@@@@

@@@@@@ @@@@ @@



  

 

   

  

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



  

 

   

  

@

@@@ @@@@ @@@@

@@@@ @@@@@@@@

@@@@ @@@@ @@@@ @@@@@@

@@@@@@ @@@@ @@



  

 

   

  

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



  

 

   

  

@

@@@ @@@@ @@@@

@@@@ @@@@@@@@

@@@@ @@@@ @@@@ @@@@@@

@@@@@@ @@@@ @@



  

 

   

  

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



  

 

   

  

@

@@@ @@@@ @@@@

@@@@ @@@@@@@@

@@@@ @@@@ @@@@ @@@@@@

@@@@@@ @@@@ @@



  

 

   

  

À

ÀÀÀ ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ ÀÀÀÀÀÀ

ÀÀÀÀÀÀ ÀÀÀÀ ÀÀ



Concrete

Insulation

0

0

2

4

6

8

10

12

14

2 4 6 8 10 12

Distance (ft)

Depth (ft)

14 16 18 20 22 24

–––––––––––––––––– 1992-93

03 Nov '92

15 Dec '92

12 Jan '93

02 Feb '93

09 Mar '93

Figure 14. Isotherm (32°F) for the winter of 1992–93.



 

 



  



 

@

@@@ @@@@

@@@@ @@@@

@@@@

@@@@ @@@@@@@@ @@@@

@@@@@@@@@@@@

@@@@ @@



 

 



  



 

À

ÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀ



 

 



  



 

@

@@@ @@@@

@@@@ @@@@

@@@@

@@@@ @@@@@@@@ @@@@

@@@@@@@@@@@@

@@@@ @@



 

 



  



 

À

ÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀ



 

 



  



 

@

@@@ @@@@

@@@@ @@@@

@@@@

@@@@ @@@@@@@@ @@@@

@@@@@@@@@@@@

@@@@ @@



 

 



  



 

À

ÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀ



 

 



  



 

@

@@@ @@@@

@@@@ @@@@

@@@@

@@@@ @@@@@@@@ @@@@

@@@@@@@@@@@@

@@@@ @@



 

 



  



 

À

ÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀ



 

 



  



 

@

@@@ @@@@

@@@@ @@@@

@@@@

@@@@ @@@@@@@@ @@@@

@@@@@@@@@@@@

@@@@ @@



 

 



  



 

À

ÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀ



 

 



  



 

@

@@@ @@@@

@@@@ @@@@

@@@@

@@@@ @@@@@@@@ @@@@

@@@@@@@@@@@@

@@@@ @@



 

 



  



 

À

ÀÀÀ ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀ

ÀÀÀÀ

ÀÀÀÀ ÀÀÀÀÀÀÀÀ ÀÀÀÀ

ÀÀÀÀÀÀÀÀÀÀÀÀ

ÀÀÀÀ ÀÀ



0

0

2

4

6

8

10

12

14

2 4 6 8 10 12

Distance (ft)

Depth (ft)

14 16 18 20 22 24

–––––––––––––––––– 1990-91

26 Nov '90

17 Dec '90

15 Jan '91

19 Feb '91

19 Mar '91

Concrete

Insulation

Figure 12. Isotherm (32°F) for the winter of 1990–91.
9

70

60

50

40

30

20

10

0

–10

Temperature (°F)

1990-91

Above

Below

–––––––––––––––

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

70

60

50

40

30

20

10

0

–20

–10

Temperature (°F)

1991-92

Above

Below

–––––––––––––––

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

70

60

50

40

30

20

10

0

–10

Temperature (°F)

1992-93

Above

Below

–––––––––––––––

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

a. 1990–91.

b. 1991–92.

c. 1992–93.

Figure 15. Temperatures above and below horizontal ground

insulation.

60

50

40

30

Temperature (°F)

1990-91 –––––––––––––

A1

A3

B25

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

60

50

40

30

Temperature (°F)

1991-92 –––––––––––––

A1

A3

B25

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

60

50

40

30

Temperature (°F)

1992-93 –––––––––––––

A1

A3

B25

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

a. 1990–91.

b. 1991–92.

c. 1992–93.

Figure 16. Temperatures under floor insulation and at

toe of footing.
indices, with the 1991–92 winter being the most

severe and the 1990–91 and 1992–93 winters being less severe and approximately equal. This

holds true for the end of the freezing season;

however, it becomes evident in the figures that at

the beginning of the 1990–91 season the temperatures are uncharacteristically cold. This was the

winter when the addition was still under construction and was heated only occasionally until

the first of December. Figure 19 further illustrates

the importance of using the heat loss from the

building in an SIF design. Given that the 1990–91

and the 1992–93 winters had approximately the

same indices, the temperatures at the sensors are

clearly lower for the 1990–91 winter than for the

1992–93 winter. Assuming the heat was on consistently from December 1, 1990, it took almost two

months for the temperatures to return to values

similar to the 1992–93 winter values.

 Figure 20 shows how temperatures decrease as

the distance from the heated foundation in10

60

50

40

30

Temperature (°F)

Sensor B25 –––––––––––––––––

1990-91

1991-92

1992-93

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

60

50

40

20

30

Temperature (°F)

Sensor A27 –––––––––––––––––

1990-91

1991-92

1992-93

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

Figure 17. Yearly temperatures at toe of footing.

Figure 18. Yearly temperatures under horizontal ground

insulation.

creases. All the measurements were taken 2 ft below grade. Sensor A6 is located under the center

of the addition, B25 at the toe of the footing, A28

under the center of the horizontal ground insulation, and B4 in the control area. The figure also

shows how the soil temperatures under the foundation (i.e., A6 and B25) change very little from

winter to winter even though the freezing indices

are quite different.

CONCLUSIONS

 The shallow insulated foundation used at the

addition for the Galena, Alaska, aircraft control

tower was a cost-effective alternative to a more

conventional footing design. Placed at only 20 in.

below grade where the expected frost depth may

reach 12 ft, the shallow foundation was protected

from potential frost damage by extruded polystyrene insulation. Because the site is unique

(i.e., remote), an accurate estimate of economic
11

60

50

40

30

Temperature (°F)

A1 Sensor –––––––––––––––––

1990-91

1992-93

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

60

50

40

20

30

Temperature (°F)

A30 Sensor –––––––––––––––––

1990-91

1992-93

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

60

50

40

30

Temperature (°F)

B26 Sensor –––––––––––––––––

1990-91

1992-93

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

Figure 19. Temperatures 1990–91 vs. 1992–93.

a. A1 sensor.

b. A30 sensor.

c. B26 sensor.

Figure 20. Temperatures taken 2 ft below grade.

60

40

0

20

–20

Temperature (°F)

1990-91 –––––––––––––

A6

B25

A28

B4

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

60

40

0

20

–20

Temperature (°F)

1991-92 –––––––––––––

A6

B25

A28

B4

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

60

40

0

20

–20

Temperature (°F)

1992-93 –––––––––––––

A6

B25

A28

B4

10 20 20 10 20 10 20 10 20 10 20 10 20 10 20 10 20 10

Sep Oct Nov Dec Jan Feb Mar Apr May

a. 1990–91.

b. 1991–92.

c. 1992–93.
12

savings could not be made; however, based upon

the site foreman’s assessment, it saved considerable time and materials over a conventional

foundation. This was not only a case of how

much the SIF saved in dollars, but also a case of

whether the project could have been built at all

given the availability of funds, manpower, equipment, building supplies, and construction timetable.

 Observations made during the three winters of

this study showed the freezing front never

threatened the bottom of the footing, even during the very cold winter of 1991–92, a design

freezing year that had an associated frost depth

of approximately 13.5 ft in the control area. Soil

temperatures around the foundation varied

according to the outside temperatures: the higher

the freezing index, the lower the soil temperatures.

As expected, the soil temperatures decreased the

farther they were from the foundation. During the

first year of observations, the soil temperatures

around the foundation were significantly lower

than in other similarly severe winters. This can

be attributed to the fact that the building was

only partially heated during the construction

phase, thus reducing the amount of heat loss to

the underlying soil and resulting in lower soil

temperatures. It was obvious that the heat loss

from the foundation plays a critical role in the SIF

design.

LITERATURE CITED

Farouki, O. (1992) European foundation designs

for seasonally frozen ground. USA Cold Regions

Research and Engineering Laboratory, Monograph 92-1.

NBI (1986) Slab-on-grade with foundation wall:

Heated buildings. In Building Details. Norwegian

Building Research Institute, Worksheet A521.811.

Torgersen, S.E. (1976) Frost protection of floor on

groundwall. Frost I Jord, 17(10): 287–314.
1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

6. AUTHORS

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION

 REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

 AGENCY REPORT NUMBER

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

14. SUBJECT TERMS 15. NUMBER OF PAGES

16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

 OF REPORT OF THIS PAGE OF ABSTRACT

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std. Z39-18

298-102

REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and

maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information,

including suggestion for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington,

VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.

March 1997

Shallow Insulated Foundation at Galena, Alaska: AT42-CA-D05

A Case Study

Lawrence S. Danyluk

U.S. Army Cold Regions Research and Engineering Laboratory

72 Lyme Road Special Report 97-7

Hanover, New Hampshire 03755-1290

Office of the Chief of Engineers

Washington, DC 20314-1000

Approved for public release; distribution is unlimited.

Available from NTIS, Springfield, Virginia 22161.

16

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL

A 2000-ft2 addition to an aircraft control tower was constructed at Galena, Alaska, during the summer of 1990.

Because of limited resources, a shallow insulated foundation (SIF) was specified instead of a traditional foundation (one in which the bottom of the footing is placed lower than the anticipated depth of frost penetration). An

SIF design allows the footing to be placed at a much shallower depth by incorporating the use of strategically

placed insulation around the foundation. The insulation utilizes heat from the building and surrounding soil,

redirects it to the area around the foundation, and thus reduces the frost penetration.

Frost depth

Foundation

Heat loss

Insulation

Temperature