NATIONAL BUREAU OF STANDARDS REPORT

9381

PROGRESS REPORT Oil EXPOSURE OF NEW ROOFING SYSTEMS

by

Thomas H* Boone and William C. Cullen

Materials and Composites Section

Building Research Division

Institute for Applied Technology

Sponsored by

Office of the Chief of Engineers, U„S» Array

Directorate of Civil Engineering, U.S. Air Force

Naval Facilities Engineering Command, U. S. Navy

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards is a principal focal point in the Federal Government for assur- ing maximum application of the physical and engineering sciences to the advancement of technology

in industry and commerce. Its responsibilities include development and maintenance of the national

standards of measurement, and the provisions of means for making measurements consistent with

those standards; determination of physical constants and properties of materials; development of methods for testing materials, mechanisms, and structures, and making such tests as may be necessary, particularly for government agencies; cooperation in the establishment of standard practices

for incorporation in codes and specifications; advisory service to government agencies on scientific and technical problems; invention and development of devices to serve special needs of' the Govern- ment; assistance to industry, business, and consumers in the development and acceptance of commercial standards and simplified trade practice recommendations; administration of programs in cooperation with United States business groups and standards organizations for the development

of international standards of practice; and maintenance of a clearinghouse for the collection and

dissemination of scientific, technical, and engineering information. The scope of the Bureau’s

activities is suggested in the following listing of its three Institutes and their organizational units. Institute for Basic Standards. Applied Mathematics. Electricity. Metrology. Mechanics. Heat. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radiation Physics. Radio Standards

Laboratory:* Radio Standards Physics; Radio Standards Engineering. Office of Standard Reference

Data. Institute for Materials Research. Analytical Chemistry. Polymers. Metallurgy. Inorganic Materials. Reactor Radiations. Cryogenics.* Materials Evaluation Laboratory. Office of Standard Refer- ence Materials. Institute for Applied Technology. Building Research. Information Technology. Performance

Test Development. Electronic Instrumentation. Textile and Apparel Technology Center. Technical

Analysis. Office of Weights and Measures. Office of Engineering Standards. Office of Invention end

Innovation. Office of Technical Resources. Clearinghouse for Federal Scientific and Technical

Information.**

‘Located at Boulder, Colorado, 80301. “Located at 5285 Port Royal Road, Springfield, Virginia, 22171.
NATIONAL BUREAU OF STANDARDS REPORT

ms PROJECT NBS REPORT

421.04-12-4212447 31 July 1966 9381

PROGRESS REPORT ON EXPOSURE OF NEW ROOFING SYSTEMS

by

Thomas H. Boone and William C. Cullen

Materials and Composites Section

Building Research Division

Institute for Applied Technology

Sponsored by

Office of the Chief of Engineers, U.S. Army

Directorate of Civil Engineering, U.S. Air Force

Naval Facilities Engineering Command, U.S. Navy

IMPORTANT NOTICE NATIONAL BUREAU OF ST

for use within the Government, and review. For this reason, th whole or in part, is not authoi Bureau of Standards, Washingt

the Report has been specifically

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

ss accounting documents intended

subjected to additional evaluation

listing of this Report, either in

; Office of the Director, National

the Government agency for which

opies for its own use.

li. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PROGRESS REPORT ON EXPOSURE OF NEW ROOFING SYSTEMS

by

Thomas H. Boone and William C. Cullen

I. INTRODUCTION

Many new roofing materials and roof systems have appeared on the market during

the past decade. Some of these systems have been introduced as substitutes for

f* conventional types of bituminous roofings for both flat and steep roof decks,

whereas, others have been developed to serve a particular need which conventional

roofs can accomplish only with difficulty. Obviously, in some cases, the new

systems fulfill both needs. In fact, a few of the newer systems allow for the

utilization of the roof areas for work or recreation.

A previous report^)

^

gives our observations of the performance of some of

these systems under service conditions. In addition, performance testing or new

( 2 \ roof systems on Guam and Okinawa have also been described in a previous report. v J

This report gives observations of roofing materials exposed to the weather at the

National Bureau of Standards, Washington, D.C. site from May 1964 to June 1966.

U Figures in parenthesis indicate the literature reference at the end of this

report.

1
2. EXPOSURE SITE AND MATERIALS

2.1 Exposure Site

The building selected for the exposure tests was a single-story structure having

a gable type roof deck and constructed of thin-shell concrete. This has been described in reference (3). The slope of the roof deck from ridge to eave was about \\

inch per foot. The four foot wide panels were connected to each other by aluminium

bolts and the joint was caulked with a polysulfide sealant. The uncoated concrete

roof panels were exposed to the elements almost 10 years before this series of

tests were inaugurated. The interior of the building was open to outside air

circulation both winter and summer. The building is shown in figure 1.

2.2 Roofing Materials

Two types of roofing were evaluated in the program; prefabricated sheets and

liquid-applied coatings.

For the most part the sheet materials consisted of a laminate of a weatherproof

elasfcromeric film and an asbestos felt reinforcing backing and were applied to the

concrete deck with an organic solvent-based adhesive. In many cases the side laps

were taped.

The liquid-applied roofings were brushed, rolled, or sprayed in multilayers

directly on the concrete deck. These systems consisted of: chloroprene, neoprene,

and chlorosulfonated polyethylene (Hypalon), ^/butyl -rubber with polyvinylchloride/

acetate copolymer, silicone rubber, polyurethane foam, asphalt, and butyl rubbers

either emulsified or dissolved in a volatile solvent. Reinforcement mediums of fiber

cloth, glass random mdt, or chopped glass fibers were frequently employed.

2 / Registered trade marks are used in this report in order to identify the materials

or mechanical device more adequately. In no case does such identification imply

recommendation or endorsement by the National Bureau of Standards nor does it

imply that the material identified is necessarily the best available for the purpose .

2
FIGURE

1.

BUILDING

OF

PRECAST

THIN

SHELL

PANELS

USED

FOR

TEST

ROOFS

In some cases a decorative and protective top coating was applied while in

others the material was left exposed to the weather.

Two traffic deck systems were also included. Locations of the roofing materials

on the test roof are illustrated in figure 2.

From the beginning of these experimental installations, it was recognized that

the performance of the test materials may be jeoparized by careless or untrained

mechanics. The test roofs that are described herein were therefore placed under

well controlled conditions. Highly skilled employees of the manufacturer, assisted

by personnel of MBS, were used to install the roofs. The recommendations of the

manufacturer in respect to the method of application, were followed as nearly as

possible.

3, OBSERVATIONS

The primary objective of this investigation was to determine the weather

resistance of some of the newer roofing systems. Further objectives were to

obtain costs of material and application and information on utilization and

application techniques. The manufacturers of the various systems are kept

informed on the current performance of their respective materials. As a result

of this exchange of information formulations have been changed where warranted.

3
Butyl Latex/Acrylic

Butyl Latex

Butyl Latex/Hypalon

Neoprene /Hyp a Ion

Silicone

Butyl Latex/Chopped Glass

Asphalt Emul sion/Chopped Glass

Over

Coated Base Sheet

Hyp a Ion, Tedlar* &

Polyisobutylene Sheets

Neoprene/Hypalon

Rubberized-Asphalt Sheet

Neoprene/Tile Silicone Polyurethane Foam

Traffic Deck Traffic Deck

Silicone

Figure 2 . Location of roofing materials on test roof
3.1.1

3.1 Liquid - Applied Systems

a . Butyl Latex with Acrylic Top Coat Applied May 7, 8, 1966

In the first spijay application of butyl latex (wet film thickness of 10 to

15 mils.) a lightweight fiberglass scrim was placed. After 3 hours drying a

second coat (40 mils, wet film thickness) of butyl latex was placed over the

scrim. After 24 hours cure a top spray coating of modified acrylic emulsion was

applied to provide protection from dirt accumulation. The wet film thickness

of this top surface was 10-15 mils.

b . Results

Within 2 months large cracks in acrylic top coating were observed. As a

result, in October, 1965 the complete system was ruined and a new system was

reapplied using an improved formulation for the top coating. During the winter

of '65- '66 small cracks again were observed in the acrylic coating and by May

1966, (7 months later) were quite evident as shown in figures 3 and 4. The

butyl base coating which became exposed by the open cracks in the acrylic coating

had a dark, dirty appearance.

3.1.2

a . Butyl Latex; No top coating

The roofing system was applied in the same manner and at the same time

(May 7, 1964) as described in 3.1.1

b . Results

With the exception of dirt accumulation and darkening, the material showed

no signs of deterioration. See figure 7 for comparison of darkening.

4

Q o w W

P4

M CO

O £ o H

XI

u o s W M < g

l-J £ 35 w S

§!

wH

33 9

Pc CO

H CO M O • 3 9 X X 11 Ed CJ co CO O

o.

W

FIGURE

5.

TYPICAL

CRATER-LIKE

SPOTS

ON

HYPALON

TOP

COAT.

3.1.3

a. Butyl Latex - Hypalon Top Coat

The butyl latex was applied in the same manner and at the same time (May 7,

1964) as described in 3.1*1* After curing the Hypalon (chlorosulfonated

polyethylene) coating was applied by roller with a wet film thickness of about

15 mils.

b . Results

Small crater-like spots appeared on the surface shortly after drying of the

coating. Although these spots became more visible with time (see figure 5) there

did not seem to be any break in the Hypalon coat.

3.1.4

a. Neoprene -Hyp a Ion

Two coats of black neoprene were applied with heavy nap rollers on October

28, 1963. The first coat was dry before application of second coat. One coat

of Hypalon was applied within three hours and on May 8, 1564 the second Hypalon

coat was applied. The wet film thickness of each coat was about 8 mils.

b* Results

The crater-like spots as seen on sample roof 3.1.3 were also noticeable on

the roof (see figure 5). A slight color change which may have been caused by

the black neoprene bleeding through the Hypalon was noted.

5
3 . 1.5

a . Silicone

This two component roofing system was applied with a brush in three coatsprimer, and two base coats. The primer and first coat was applied November 1963

and the second base coat May 19, 1964. Because of the heavy dirt retention

(see figure 6 and 7) another application, by the manufacturer, was placed in

a different area of the test roof on July 8 and 9, 1965.

b. Results

The second silicone test area was applied in the same steps as that of the

first with a modified formula to reduce dirt retention. Figure 8 illustrates

the heavy dirt retention of this second roof.

3 . 1.6

a „ Butyl Latex-Chopped Glass Fiber

A system using butyl latex emulsion - chopped glass fiber combination

employing a spray gun identified as the Sealzit Gun was applied at a rate of

6 to 8 gallons per 100 square feet. The emulsion-glass ratio was one gallon

of emulsion to 1/6 pound of glass.

The concrete roof test area was primed with latex on November 10, 1963

and butyl-chopped glass was applied on July 29, 1964.

b. Results

Orginally the surface was slightly off white color with the glass fibers

visible but completely coated with the latex. After two years exposure the

surface was lightbrown and glass fibers on the top surface were uncoated and

in some cases easily picked off the surface. See figure 9.

6
&o<X

X

W Ed H H 3 3

tH pH

XwH<

iJ

hJ

w2: 8W

wgu

JH

naQw< hJ :S° < ‘

fe cd < o

PSw

w o H 2 < o <d 3 o H M a S3

hJM

H

M

M

CO 3• C3 vD y

PQ

W CO PQ

Cd

O !=> 2) Pn cd o X u M w CO

FIGURE

8.

SILICONE

ROOF

AFTER 1

YEAR

EXPOSURE.

RECTANGULAR

AREA

GLEANED

3.1.7

a . Asphalt emulsion - chopped glass

This system consisted of a clay-type asphalt emulsion - chopped glass combination applied with the Sealzit Gun, The manufacturer reports the emulsion

was modified by the addition of a latex type material. The combination was

applied at a rate of about 7 gallons per 100 square feet and the emulsion-glass

ratio was one gallon to 1/3 pound glass.

The material was sprayed over the untreated concrete and over coated base

sheet applied to the concrete.

A second section of the concrete test roof was covered with the base sheet

and the first coat of the asphalt-glass was sprayed both on the base sheet and

on the untreated concrete area on November 10, 1963. The second coat of asphaltglass was applied July 29, 1964.

b. Results

Exposure of the glass fibers was evident as in the butyl systems. The

material cracked and separated between concrete panels. See figure 10, The

coated base sheet separated from the concrete and blistered. See figure 11.

3.1.8

a . Polyurethane foam

This system consisted of two spray coatings of polyurethane which foamed

in place to a total thickness of about one inch. The material foamed and dried

to touch within minutes after spray. Second coat applied fifteen minutes after

first. After one hour a brush application of white polyvinyl acetate masonry

paint was applied. A second coat of paint was applied after 24 hours.

The material was applied directly over a concrete roof panel on June 10, 1965.

7

>

y*\

X \ - % . . * *

__ \ * m&" VTJSt

7-

aO

FIGURE

11.

ASPHALT

EMULSIONCHOPPED

GLASS

OVER

COATED

BASE

SHEET.

THE

BASE

FIGURE

12.

POLYURETHANE

FOAM

SHOWING

SHEET,

SEPERATED

FROM

THE

CONCRETE

AND

SURFACE

DAMAGE

OF

TOP

WEATHER

COAT.

BLISTERED.

UNEXPOSED

PANEL

IN

UPPER

LEFT

CORNER

b. Results

On July 8, 1965 a hail storm with hail stones the size of marbles damaged the

paint coating and exposed the brownish foam. With the exception of this slight

surface damage the material is in good condition. See figure 12.

3.2 Single-ply Roof System

3.2.1

a. Hypalon Sheet

The sheet has a 20 mil-thick chlorosulfonated polyethylene white top surface

factory laminated to a 15 mil thick asbestos backing felt. The sheet was applied

directly to the concrete with an organic solvent-based adhesive, overlapped

joints and taped with Hypalon tape.

The Hypalon sheet was applied May 18, 1965.

b . Results

Within one month very noticeable brown stains appeared on the top surface.

The stains could not be removed by scrub-washing. Chalking' of the top surface

was noticed after 8 months exposure. With the increasing ‘chalking; the brown

stains disappeared. See figure 13.

3.2.2

a . Polyisobutylene Sheet

The sheet has a 20 mil thick polyisobutylene black top surface which was

laminated in the factory to a 20 to 30 mil asbestos backing felt. The sheet

was applied directly to the concrete with an organic solvent-based polyisobutylene adhesive. The laps were sealed with the adhesive® A white brushedon coating was applied to part of the roof.

The sheet was applied May 18, 1965.

8
b. Results

The black polyisobutylene surface and the coated surface have not changed

from their original appearance in one year exposure. See figure 13.

3.2.3

a. Tedlar Sheet

The sheet has a 2 mil thick white polyvinyl fluoride top surface which was

laminated in the factory to a 20 mil asbestos backing felt. The sheet was

applied directly to the concrete with an organic solvent-base adhesive. The

joints were taped with two-inch wide Tedlar tape having a pressure-sensitive

adhesive backing.

The sheet was applied May 18, 1965.

b. Results

After one year exposure there was no change in the visual appearance of the

sheet material. See figure 13. Dimensional change or deck movement caused

adhesive overlap of the tape.

3.2.4

a. Rubberized-Asphalt Sheet

This sheet has an 80 mil-thick black rubberized-asphalt top surface which

was laminated in the factory to a 20 mil asbestos backing felt. The sheet was

applied directly to the concrete with an organic solvent-based adhesive Spread

in ribbons. See figure 15. The laps were sealed with the same adhesive.

b. Results

After seven months exposure there was no visible change. See figure 14.

9
3.3 Traffic Deck

3.3.1

a. Neoprene Sheet - Flexible Tile

The system provides a membrane base sheet with a tile walking surface

applied in the following steps: neoprene primer; neoprene adhesive applied

to deck and felt side of membrane; sheet of 15 mil black neoprene top surface

factory laminated to a 20 mil asbestos backing felt contact bonded to deck;

entire sheet surface coated with the neoprene adhesive; the back of each

18xl8xl/8-inch tile also coated with the neoprene contact adhesive; tile installed

leaving 1/16-inch open joint between tiles; the completed deck rolled with heavy

roller.

The traffic deck was installed May 5 and 6, 1965.

b . Results

After one year exposure no visible change had occured. See figure 16.

3.3.2

a. SilicOne

Over the concrete panel a primer applied at the rate of 1 gallon per 100

square feet was used. A sand filled silicoQe mix was then trowled over the

surface approximately 1/16-inch thick.

The material was installed July 9, 1965.

b„ Results

After one year exposure there were no visible signs of deterioration.

Unlike the two silicone roof coatings, the surface of the traffic topping

had very little dirt retention.

10

FIGURE

15.

APPLICATION

OF

RUBBERIZED

FIGURE

16.

FLEXIBLE

TILE

TRAFFIC

DECK

ASPHALT

SHEET

WITH

ADHESIVE

APPLIED

IN

SHOWING

SLATE-LIKE

TEXTURE

MOLDED

ON

RIBBONS.

THE

SURFACE

BY

THE

MANUFACTURER.

4. SUMMARY AND CONCLUSIONS

4*1 Performance

Table 1 gives a summary of the performance of the roofings systems described

in this report. When major deficiencies were discovered the manufacturers of

the roof system were notified and encouraged to rectify the trouble or install

a modified system.

Where these products are commerically available a price range based on the

installation methods used in this test is given in Table 1. Government

specifications* where applicable, are also given.

In the fluid-applied roofings the systems using the Hypalon as a top

weather coating seem to maintain their original appearance and showed no visible

signs of deterioration . The polyurethane foam roofing also seems to have

excellent performance. This system serves as insulation as well as roofing.

Recommendations have been made to the manufacturer to provide a more elastic

and durable top weather coating on the polyurethane foam.

The single-ply sheet materials all performed well. The manufacturer of

the Hypalon sheet claims that their newer material does not chalk.

The two traffic deck materials were placed at the only access to the roof

so as to receive all traffic visitors. However this traffic was light, less

than 10 persons a month. Both systems were designed to provide roofing systems

and walkway surfaces. The two systems performed well.

11
4.2 Application

As mentioned in the beginning of this report highly skilled and experienced

personnel were obtained to install each roof. In spite of this, time consuming

delays on two of the three systems using spray equipment were experienced. Each

delay was caused by mal- functioning of the specialized spray equipment. The

coatings using chopped glass and the polyurethane, because of mixing with the

glass or activator at the nozzel must be applied with specialized equipment.

Roller application proved most satisfactory in this series of tests.

With the exception of the need to warm the adhesive used for applying the

rubberized-asphalt sheet all other sheet systems were applied with no difficulty*

The authors acknowledge the advice of the various members of the TriService Committee in the selection of materials for study and their assistance in evaluating performance. Representatives of the following companies

also cooperated in this program by providing material, labor, and suggestions*

5 . ACKNOWLEDGMENT

Armstrong Cork Co,

B. F, Goodrich Co,

Enjay Chemical Go.

Flintkote Co.

Bilton Insulation & Supply Inc.

E. I. du Pont de Nemours and Co.

General Electric Co,

Gibson-Homans Co,

Johri s -Manvi 1 1 e Pittsburgh Plate Glass Co

Shell Development Co.

12
6 . REFERENCES

(1) NBS Report 7737 "Progress Report on New Roof Systems" by William C. Cullen

(November 1962).

(2) NBS Report 8352 "Performance of Roofings on Guam, M.I. and Okinawa, R.I."

by William C. Cullen (20 May 1964)

(3) Amirikian, Arshem; "Multipurpose Building of Precast Thin-Shell Panels"

Journal of American Concrete Institute, No. 12 Vol. 31, p. 1243-1252 (June 1960)

7 . NOTE

Neither the contents of this report nor the fact that the investigation

was conducted by the National Bureau of Standards may be used for advertising

or promotional purposes.

13
Table 1 - Summary

Roofing System

Age

Years Appearance Condition

Cost Per

Square

Fluid - Applied

Butyl latex 2 Fair (Dirty) Good

Butyl latex/Acrylic 2 Poor (Cracking) Poor (Cracking)

Butyl latex/Hypalon 2 Good Good $15-$20

Neoprene/Hypalon

^

2 Good (Slight Yellowing) Good $25-$35

1 / Neoprene/Hypalon 2 Good Good $25-$35

Silicone 2 Poor (Very Dirty) Good

Silicone 1 Poor (Very Dirty) Good

Butyl latex/chopped glass 2 Fair (Dirty) Fair (Glass

Asphalt/chopped glass

^ 2 Fair (Deterioration)

exposed)

Poor (Glass $15-$25

Polyurethane Foam 1 Fair (Paint Chipping)

exposed cracking

Good

at joints)

Single-ply Sheet

Hyp a Ion 1 Good Fair (Chalking) $32-$45

Polyisobutylene ~ ^

1 Good Good

Tedlar

^ ^ 1 Good Good $35-$45

Rubberized-Asphalt 1 Good Good

Traffic Deck

Silicone 1 Good Good $100

Neoprene /Tile 1 Good Good $225-$275

U "Elastomer Roofing - Fluid Applied for Concrete Roof Decks" Dept, of the Army, OCE

Draft Military Guide Specification CE - 220.13
—2 / "Roofing Systems" General Services Administration, Public Building Service

Guide Specification 213-4 (April 1965)

^

"Elastromeric Roofing Systems" Department of the Navy, Bureau of Yards and

Docks, Type Specification TS-R8, (21 May 1965) —4 / "Guide Specification for Elastomeric Roofing Systems", Department of the Air Force

Facility Design and Construction Air Force Pamphlet AFP88-007-2 (18 March 1966)