Two-Year Wisconsin 

Thermal Loads for Roof 

Assemblies and Wood, 

Wood–Plastic Composite, 

and Fiberglass Shingles

Jerrold E. Winandy

Michael Grambsch

Cherilyn A. Hatfield

United States

Department of

Agriculture

Forest Service

Forest

Products

Laboratory

Research

Note

FPL–RN–0301
November 2005

Winandy, Jerrold E.; Grambsch, Michael; Hatfield, Cherilyn. 2005. Twoyear Wisconsin thermal loads for roof assemblies and wood, wood–plastic 

composite, and fiberglass shingles. Research Note FPL-RN-0301. Madison, 

WI: U.S. Department of Agriculture, Forest Service, Forest Products 

Laboratory. 11 p.

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Abstract

Temperature histories for various types of roof shingles, 

wood roof sheathing, roof rafters, and non-ventilated 

attics are being monitored in outdoor attic structures using 

simulated North American light-framed construction. This 

report presents 2-year data histories for annual thermal 

loads for western redcedar, wood–thermoplastic composite, 

and fiberglass shingles and for wood-based composite roof 

sheathing, wood rafters, and attics under these shingles. 
Introduction

Comprehensive temperature histories for a roof system 

under fiberglass shingles were recorded and reported 

after 8 years in Madison, Wisconsin (43°N latitude), and 

4 years in Starkville, Mississippi (33°N latitude) (Winandy 

and Beaumont 1995, Winandy and others 2000). Summer 

shingle temperatures for five types of shingle materials 

and their resulting influence on the roof system and attic 

temperatures were reported by Winandy and others (2004). 

This data paper and a related report (Winandy 2005) are 

the next in a series of papers dedicated to quantifying field 

thermal loads on shingles, sheathing, rafter lumber, and 

attic air space in traditional North American light-framed 

construction. The overall program has involved a series of 

interrelated studies conducted over a 14-year period. Roof 

temperature data such as presented in this paper can also be 

applied to predictive roof-temperature models (TenWolde 

1997) to make performance interpretations for other building designs. The project reported here is part of a long-term 

field-monitoring program to define thermal loads on North 

American light-framed construction. It is also helping us 

understand the critical performance issues related to durability, thermal stability, and ultraviolet (UV) weathering for 

wood–thermoplastic roofing shingles.

Objective 

An objective of the roof temperature assessment project is 

to collect field data documenting the actual thermal load 

history of various wood components and shingle materials 

as used in traditional light-framed structures. This report 

provides 2-year roof temperature histories as measured for 

a location in southern Wisconsin near Madison. Thermal 

load histories are critical parameters in assessing the longterm service life of roof coverings and materials within the 

entire roof system. Thermal load data are critical to any 

subsequent modeling of the rates of thermal degradation for 

roof shingles, wood composite sheathing, and rafter lumber 

(Lebow and Winandy 1999). They can also provide valuable 

insight into the influence of individual roof-system components on potential energy costs required to heat or cool the 

structure. 

Methods

Exposure Structures 

In the summer of 1991, five field exposure structures 

(Fig. 1) were constructed near Madison, Wisconsin 

(43° latitude). In Madison, the average incidence angle of 

sunlight is 19.5° from the southern horizon on the winter 

solstice (December 21) and 43° on the summer solstice 

(June 21). The annual average declination angle is 31.25°. 

The Wisconsin exposure structures (WI structures) were 

constructed to face south in a shadeless area open to direct 

sunlight. The structures were spaced far enough apart to 

prevent any one structure from shading the next structure. 

Winandy and Beaumont (1995) described the construction 

of the WI structures in detail and reported 3-year annualized 

data.

In 1994, matched exposure structures were built at the 

Mississippi Forest Products Laboratory, Mississippi State 

Two-Year Wisconsin Thermal Loads 

for Roof Assemblies and Wood, 

Wood–Plastic Composite, and 

Fiberglass Shingles

Jerrold. E. Winandy, Supervisory Research Wood Scientist

Michael Grambsch, Supervisory Electronics Technician

Cherilyn Hatfield, Statistician

Forest Products Laboratory, Madison, Wisconsin

Figure 1—Exposure structures located at Forest Products Laboratory test site near Madison, Wisconsin. All 

five units were similar except for roofing materials and 

were instrumented for long-term temperature monitoring of roof assemblies. Shown, from the foreground, are 

black fiberglass shingles, western redcedar shingles 

(being installed), wood–thermoplastic composite shingles (two structures—closer with lath and further without lath), and white fiberglass shingles.
Research Note FPL-RN-0301

2

University, in Starkville, Mississippi (33.5° latitude), as 

part of an ongoing effort to relate temperatures histories 

in matched northern to southern U.S. roof systems. In 

Starkville, the average incidence angle of sunlight is 32.3° 

from the southern horizon on the winter solstice and 74.8° 

on the summer solstice. The annual average declination 

angle is 53.5°. The exposure structures in Mississippi 

(MS structures) were constructed to face south in a shadeless area open to direct sunlight. As for the WI structures, 

the MS structures were spaced far enough apart to prevent 

any one structure from shading the next structure. The data 

from the MS structures provide a direct measure of a more 

severe (higher solar loading) location compared with Madison, Wisconsin. 

The WI and MS structures were identical. The structures 

were 3.7 m wide by 4.9 m long and constructed to simulate 

part of a typical multifamily attic–roof system in which 

U.S. Model Building Codes sometimes allow the use of 

fire-retardant-treated plywood roof sheathing. To replicate 

this type of construction on a smaller scale, the 3.7-m-wide 

structures simulated in cross section the 1/8- to 3/8-span 

section of a 14.8-m span, 3:12 pitch roof system in both roof 

area and attic volume (Winandy and Beaumont 1995). Each 

exposure structure was completely enclosed and unventilated. The four exterior walls were sheathed with 12-mm-thick, 

200-mm-grooved Southern Pine siding attached to nominal 

2- by 4-in. (standard 38- by 89-mm) wall studs. The exterior 

surfaces were painted with a light gray (almost white) paint. 

The walls, floors, and roof system were not insulated. 

Recording of Temperature 

To assess the effect of fiberglass shingle color, from 1991 

to 2001 the WI structures were roofed with black or white 

fiberglass shingles weighing 106 kg/square. The MS structures were roofed with black fiberglass shingles. The fiberglass shingle manufacturer reported reflectance values of 

3.4% and 26.1% for matched black and white shingles, respectively. Both black and white shingles had an emissivity 

rating of 0.91 as reported by the manufacturer. The WI and 

MS structures were instrumented with type-t thermocouples 

placed at various locations within the structures. 

In the fall of 2001, the shingles and plywood sheathing were 

removed from one white-shingled and two black-shingled 

structures at the Wisconsin site. These structures were resheathed with 12-mm-thick oriented strandboard (OSB) 

roof sheathing. The commercial OSB was made from aspen 

flakes and an isocyanate resin. One structure was then shingled with western redcedar (WRC) shingles directly over 

felt, and the other two structures were shingled with prototype wood–thermoplastic composite (WTPC) shingles 

(Figs. 1 and 2). The WTPC shingles were 0.86 m wide by 

0.45 m high, made from a 50/50 blend of wood flour and 

high-density polyethylene, and compression molded 

(Fig. 3). In one WTPC construction, the shingles were laid 

directly over felt as were the WRC shingles. This type of 

application is usually considered to represent a worst-case 

scenario for shingle durability. In the other WTPC construction, the shingles were laid over a horizontal course of 9-

mm-thick lath that, in turn, was laid over a similar vertical 

course of lath.

We began monitoring the temperature histories of the five 

WI structures in the summer of 2002. As described in 

the previous text, in four of these structures the shingles 

(WRC, WTPC, white fiberglass, and black fiberglass) were 

applied directly over felt (i.e., without lath). In the fifth 

structure, WTPC shingles were applied over lath. Temperatures were monitored in five locations: shingles, sheathing 

(two measurements), rafter, attic air, and outside ambient 

air. The shingle temperature was measured using a type-t 

thermocouple embedded at the mid-point of the shingle 

cross-section and located about one-third the distance from 

the roof line, between the peak and lower eave. Type-t thermocouples were also placed as follows: (a) embedded 

between OSB or plywood sheathing and roofing paper; 

(b) embedded about 0.5 mm into bottom layer of sheathing; 

Figure 2—Side view of installed shingles: (a) western 

redcedar (WRC), (b) wood–thermoplastic composite 

(WTPC), and (c) fiberglass. 
3

(c) embedded at mid-point of nominal 2 by 6 (38- by 140-

mm) rafter; and (d) suspended 200 mm away (extending 

inside) from back wall, about 1.55 m from floor. To measure 

the outside air temperature, a thermocouple was located 

under a metal shield (i.e., covered) about 50 mm away (extending outside) from the back wall, about 2 m above the 

ground. A detail description of thermocouples and installation was reported previously (Winandy and Beaumont 

1995). 

At each thermocouple location, temperature data were collected every 5 min; an hourly average was recorded using a 

Campbell–Scientific (Logan, Utah) model CR10 data logger and a model AM416, 32-channel multiplexer. The data 

logger had a reported accuracy of 0.2% over a service temperature range of 55°C to 85°C. The Wisconsin installation 

as reported for 2003 and 2004 was identical to that used by 

Winandy and others (2004).

The individual temperature histories of WRC and WTPC 

shingles exposed in Wisconsin were monitored from January 2003 to December 2004 to assess the influence of the 

shingles on solar-induced thermal loads imparted to the 

wood roof truss lumber, OSB roof sheathing, and attic air 

temperatures experienced in traditional North American 

light-framed constructions. Each annual temperature history 

was then compared to that of similarly designed roof assemblies under traditional black and white fiberglass shingles. 

To develop the temperature history for each roof covering 

and component, we calculated the number of hours recorded 

for each thermocouple into 5°C temperature bins. These 

5°C bins (0°C to <5°C, 5°C to <10°C, ..., 70°C to 75°C) are 

hereafter defined as “exceedence temperatures.” The value 

reported as the exceedence temperature for 70°C is thus the 

number of hours that the temperature at that thermocouple 

location equaled or exceeded 70°C but was lower than 

75°C. 

Results and Discussion

Tables 1 and 2 show data for exposure structures in Madison, Wisconsin, for the years 2003 and 2004, respectively. 

Annual temperature histories (−40°C to 75°C ) for 2003 and 

2004 were calculated for shingles (Fig. 4), top and bottom 

surfaces of roof sheathing (Figs. 5 and 6), rafters (Fig. 7), 

and attic air (Fig. 8).

The 2-year mean annual temperatures recorded for shingles 

during this period were 11.9°C and 10.5°C for black and 

white fiberglass shingles, respectively; 10.2°C for WRC 

shingles; and 9.9°C and 10.1°C for WTPC shingles with 

and without lath, respectively. The maximum temperatures 

recorded during this period were 70.7°C and 61.0°C for 

black and white fiberglass shingles, respectively; 48.2°C for 

WRC shingles; and 45.7°C and 46.2°C for WTPC shingles 

with and without lath, respectively. On the warmest summer 

days, black fiberglass shingles were more than 10°C warmer 

than matched white fiberglass shingles and almost 22°C to 

25°C warmer than comparable WRC or WTPC shingles. 

The temperatures of the other components in the various 

roof assemblies and the attic air temperatures followed the 

same trends. The maximum temperatures recorded at the 

top layer of the roof sheathing were 74.9°C and 61.4°C 

for black and white fiberglass shingled roofs, respectively; 

47.6°C for WRC; and 43.5°C and 48.2°C for WTPC with 

and without lath, respectively. For the bottom layer of the 

roof sheathing, the maximum temperatures recorded were 

52.7°C and 46.6°C for black and white fiberglass shingles, 

44.1°C for WRC, and 43.3°C and 44.2°C for WTPC with 

and without lath, respectively. For the rafter, the maximum 

temperatures were 49.1°C and 43.8°C for black and white 

fiberglass shingles, 42.1°C for WRC, and 42.0°C and 

42.4°C for WTPC with and without lath, respectively. The 

maximum attic air temperatures were 48.9°C and 44.1°C for 

black and white fiberglass shingles, 42.6°C for WRC, and 

42.4°C and 42.6°C for WTPC with and without lath, 

respectively. 

The overall roof temperature data recorded from July to 

September 2003 and 2004 (Tables 1 and 2) for both black 

and white fiberglass shingled structures were found to be 

very similar to data previously reported for July to September 2002 (Winandy and others 2004) and over an 8-year 

period from 1992 to 1999 (Winandy and others 2000). 

We also compared the sheathing, rafter, and attic air temperature histories for 2003 to the previously reported 

8-year annualized (i.e., averaged) thermal load histories 

Figure 3—Components for WTPC structure: (a) roof 

tiles, (b) shingles. 

 Temperature Histories for Roof Assemblies and Wood, Wood–Thermoplastic Composite, and Fiberglass Shingles
4

Research Note FPL-RN-0301

(Winandy and others 2000). We found that temperatures 

were more extreme in 2003: noticeably warmer exposure 

temperatures occurred in the top of the sheathing in the 

summer of that year and colder temperatures in both the top 

and bottom of the sheathing in the winter (Fig. 9). The 2003 

rafter and attic air temperature histories were similar to the 

1992–1999 annualized data (Fig. 10). The 2004 temperature 

histories of all roof-system components and the attic air 

temperatures were found to be similar to the 1992–1999 annualized data (Figs. 11, 12). 

Conclusion

This paper describes 2-year thermal load histories of various wood components in traditional light-framed structures 

using western redcedar, wood–thermoplastic composite 

(WTPC), or black and white fiberglass shingles. The data 

clearly show that in the summer the temperature of black 

fiberglass shingles is much higher than that of white fiberglass shingles. Western redcedar (WRC) and WTPC 

shingles have similar temperatures but are cooler than either 

black or white fiberglass shingles. The data also indicate 

that during a typical summer or winter season, the sheathing 

under both black and white fiberglass shingles is sometimes 

warmer than the shingles themselves. The temperature of 

sheathing under WTPC and WRC shingles is virtually the 

same, but generally much cooler than that of sheathing 

under fiberglass shingles. Sheathing under WTPC shingles 

applied on lath is noticeably cooler than sheathing under 

WTPC shingles installed directly on felt. 

A detailed analysis of these thermal load histories is available (Winandy 2005). That report also includes a comprehensive comparison of the thermal load histories to previous 

findings.

Literature Cited 

Lebow, P.K.; Winandy, J.E. 1999. Verification of kineticsbased model for long-term effects of fire-retardants on 

bending strength at elevated temperatures. Wood and Fiber 

Science. 31(1): 49–61. 

TenWolde, A. 1997. FPL roof temperature and moisture model. Res. Pap. FPL–RP–561. Madison, WI: U.S. 

Department of Agriculture, Forest Service, Forest Products 

Laboratory. 

Winandy, J.E. 2005. Analysis of two-year Wisconsin temperature histories for wood roof assemblies using wood, 

wood–thermoplastic-composite, or fiberglass shingles. Journal of Thermoplastic Composite Materials. (submitted for 

publication).

Winandy, J.E.; Beaumont, R. 1995. Roof temperatures in 

simulated attics. Res. Pap. FPL–RP–543. Madison, WI: U.S. 

Department of Agriculture, Forest Service, Forest Products 

Laboratory.

Winandy, J.E.; Barnes, H.M.; Hatfield, C.A. 2000. Roof 

temperatures histories in matched attics in Mississippi and 

Wisconsin. Res. Pap. FPL–RP–589. Madison, WI: U.S. 

Department of Agriculture, Forest Service, Forest Products 

Laboratory. 

Winandy, J.E.; Barnes, H.M.; Falk, R.H. 2004. Summer 

temperatures of roof assemblies using western redcedar, 

wood-thermoplastic composite, or fiberglass shingles. 

Forest Products Journal. 54(11): 27–33.
5

 Temperature Histories for Roof Assemblies and Wood, Wood–Thermoplastic Composite, and Fiberglass Shingles Table 1

—Cumulative time within each exceedence temperature range in Madison, Wisconsin, from January 1 to December 31, 2003

Temp. site b

Time (h) at various exceedence temperatures (°C)

Below 0°C Above 0°C

Shingle a >35 >30 >25 >20 >15 >10 >5 >0 >5 >10 >15 >20 >25 >30 >35 >40 >45 >50 >55 >60 >65 >70Black Shngl 2 17 102 248 414 547 987 1164 1011 1093 891 522 347 271 273 259 205 188 135 65 18 1

Top 1 18 103 260 415 541 960 1137 988 1095 848 525 322 289 247 236 221 208 178 108 52 8Bot

— 2 44 213 410 563 947 1165 1036 1044 995 729 440 397 358 255 147 15

—

—

—

—

Rafter

— 1 34 205 396 584 930 1193 1019 1052 1019 781 501 433 329 241 42

—

—

—

—

—

Attic

— 1 33 204 401 589 946 1172 1031 1035 1023 780 503 435 328 241 38

—

—

—

—

—

WRC Shngl 

— 4 53 210 410 569 957 1221 1049 1085 996 772 488 426 304 197 19

—

—

—

—

—

Top

— 7 58 214 410 574 958 1219 1038 1097 989 734 475 419 311 211 46

—

—

—

—

—

Bot

— 1 33 205 384 590 947 1214 1074 1070 1039 840 546 413 318 86

—

—

—

—

—

—

Rafter

—

— 32 200 398 603 955 1229 1042 1074 1078 856 574 434 262 23

—

—

—

—

—

—

Attic 

—

— 29 199 380 590 954 1211 1078 1056 1065 880 563 444 278 33

—

—

—

—

—

—

WTPC with lath Shngl 

— 12 47 203 422 592 976 1225 1032 1098 1012 757 537 420 295 129 3

—

—

—

—

—

Top

— 3 35 191 405 593 978 1222 1050 1079 1034 830 555 427 292 66

—

—

—

—

—

—

Bot

— 1 34 203 401 615 950 1245 1029 1081 1058 861 576 432 249 25

—

—

—

—

—

—

Rafter

—

— 31 189 398 600 951 1233 1073 1055 1080 925 604 404 214 3

—

—

—

—

—

—

Attic

—

— 29 191 387 582 965 1230 1060 1059 1079 895 601 438 230 14

—

—

—

—

—

—

WTPC w/o lath Shngl 

— 4 41 201 405 572 987 1211 1055 1082 1023 792 517 431 294 142 3

—

—

—

—

—

Top

— 7 54 211 421 589 974 1214 1051 1077 1010 727 503 406 310 182 24

—

—

—

—

—

Bot

—

— 32 195 391 591 961 1232 1049 1065 1086 838 560 425 284 51

—

—

—

—

—

—

Raft

—

— 31 191 392 599 958 1231 1061 1050 1097 892 582 434 228 14

—

—

—

—

—

—

Attic

—

— 29 186 375 567 962 1224 1072 1050 1096 893 578 452 257 19

—

—

—

—

—

—

White Shngl 3 26 135 270 405 590 1050 1151 1049 1083 873 499 364 322 296 268 214 125 36 1

—

—

Top 1 21 125 264 401 578 1004 1178 1046 1090 886 505 359 321 277 279 231 143 48 3

—

—

Bot

— 3 64 217 407 564 986 1216 1036 1113 977 668 497 424 352 205 31

—

—

—

—

—

Rafter

— 5 74 213 426 579 1011 1213 1018 1099 1002 729 508 448 314 121

—

—

—

—

—

—

Attic

— 2 53 210 400 562 974 1224 1058 1099 985 746 519 462 319 144 3

—

—

—

—

—

a Black is black fiberglass shingles; WRC, western redcedar; WTPC with lath, wood–thermoplastic composite shingles laid on lath; WTPC w/o lath, wood–thermoplastic  composite shingles laid directly on felt; white, white fiberglass shingles.b Shngl is shingle; top, top surface of roof sheathing; bot, bottom surface of roof sheathing; attic, attic air.
6

Research Note FPL-RN-0301

Table 2—Cumulative time within each exceedence temperature range in Madison, Wisconsin, from January 1 to December 31, 2004

Temp.

 site b

Time (h) at various exceedence temperatures (°C)

Below 0°C Above 0°C

Shingle a >35 >30 >25 >20 >15 >10 >5 >0 >5 >10 >15 >20 >25 >30 >35 >40 >45 >50 >55 >60 >65 >70Black Shngl 1 19 79 207 360 615 897 1021 1243 1160 994 535 387 282 264 229 192 154 94 42 9 —

Top 1 24 80 205 362 602 895 991 1223 1140 958 539 372 310 245 245 201 174 129 65 19 4Bot — 9 50 187 331 533 952 999 1204 1209 1167 723 477 385 326 175 56 1 — — — —Rafter — 6 54 173 321 530 988 1008 1194 1186 1188 812 516 417 277 110 4 — — — — —Attic — 7 51 174 327 517 973 1020 1208 1206 1199 790 498 434 271 106 3 — — — — —

WRC Shngl — 9 56 188 334 560 974 1041 1249 1183 1191 762 504 424 238 69 2 — — — — —

Top — 14 59 190 329 576 985 1033 1230 1197 1173 749 475 421 258 90 5 — — — — —Bot — 7 51 169 323 532 999 1045 1225 1223 1228 839 568 393 175 7 — — — — — —Rafter — 6 52 169 328 529 1000 1058 1218 1242 1242 902 583 376 77 2 — — — — — —Attic — 6 51 165 324 515 999 1034 1248 1239 1236 882 608 384 91 2 — — — — — —

WTPC with lath Shngl — 9 52 192 357 551 982 1057 1242 1220 1170 784 554 404 185 25 — — — — — —

Top — 7 47 176 337 557 969 1063 1234 1214 1192 855 593 391 144 5 — — — — — —Bot — 7 51 171 336 540 995 1043 1218 1262 1217 880 594 386 82 2 — — — — — —Rafter — 4 51 167 332 528 996 1058 1206 1241 1266 933 613 345 44 — — — — — — —Attic — 6 50 161 325 533 978 1050 1220 1251 1236 915 619 378 62 — — — — — — —

WTPC w/o lath Shngl — 9 52 179 338 567 974 1050 1231 1196 1200 807 531 408 209 33 — — — — — —

Top — 13 59 194 343 592 964 1043 1238 1194 1159 769 496 403 245 66 6 — — — — —Bot — 6 50 168 324 549 988 1051 1215 1224 1233 870 577 396 128 5 — — — — — —Rafter — 6 49 169 325 539 1001 1059 1199 1225 1269 905 613 359 66 — — — — — — —Attic — 5 49 160 314 536 972 1059 1202 1243 1229 925 599 406 83 2 — — — — — —

White Shngl — 21 105 203 390 656 929 1032 1246 1188 961 549 410 324 274 247 158 73 15 2 — —

Top — 18 97 205 372 643 942 1015 1225 1182 970 576 402 314 283 247 185 82 21 4 — —Bot — 14 57 184 334 586 950 1028 1254 1210 1134 729 473 440 294 92 5 — — — — —Rafter — 13 66 182 337 596 961 1022 1260 1227 1164 767 509 443 213 24 — — — — — —Attic — 10 57 180 322 568 959 1035 1250 1222 1169 773 513 456 233 37 — — — — — —

a Black is black fiberglass shingles; WRC, western redcedar; WTPC with lath, wood–thermoplastic composite shingles laid on lath; WTPC w/o lath, wood–thermoplastic  composite shingles laid directly on felt; white, white fiberglass shingles.b Shngl is shingle; top, top surface of roof sheathing; bot, bottom surface of roof sheathing; attic, attic air.
7

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

2003 shingle

0

200

400

600

800

1000 

1200 

1400 

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Exceedence temperature (�C)

2004 shingle

WTPC 

without lath 

WTPC with 

lath

WRC

White

fiberglass

Black

fiberglass

Number of hours 

Figure 4—Cumulative temperature histories of WTPC 

(with and without lath), WRC, and fiberglass shingles 

exposed from January to December in 2003 and 2004 

near Madison, Wisconsin.

0

200

400

600

800

1000 

1200 

1400 

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Exceedence temperature (�C)

2004 top of sheathing

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

2003 top of sheathing

Number of hours 

WTPC 

without lath 

WTPC with 

lath

WRC

White

fiberglass

Black

fiberglass

Figure 5—Cumulative temperature histories at top surface of roof sheathing under various types of shingles. 

 Temperature Histories for Roof Assemblies and Wood, Wood–Thermoplastic Composite, and Fiberglass Shingles
8

0

200

400

600

800

1000 

1200 

1400 

-40 -30 -20 -10 0 10 20 30 40 50 60 70

2003 bottom of sheathing

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Exceedence temperature (�C)

2004 bottom of sheathing

WTPC 

without lath 

WTPC with 

lath

WRC

White

fiberglass

Black

fiberglass

Number of hours

Figure 6—Cumulative temperature histories at bottom surface of roof sheathing under various types of 

shingles. 

Number of hours 

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

2003 rafter

0

200

400

600

800

1000 

1200 

1400 

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Exceedence temperature (�C)

2004 rafter

WTPC 

without lath 

WTPC with 

lath

WRC

White

fiberglass

Black

fiberglass

Figure 7—Cumulative temperature histories of interior 

core of roof rafters supporting sheathing under various 

types of shingles.

Research Note FPL-RN-0301
9

 Temperature Histories for Roof Assemblies and Wood, Wood–Thermoplastic Composite, and Fiberglass Shingles

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Exceedence temperature (�C)

2004 attic air

0

200

400

600

800

1000 

1200 

1400 

-40 -30 -20 -10 0 10 20 30 40 50 60 70

2003 attic air

Number of hours

WTPC 

without lath 

WTPC with 

lath

WRC

White

fiberglass

Black

fiberglass

Figure 8—Cumulative temperature histories of attic air 

temperature in structures made with various types of 

shingles.

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Top of sheathing, 8-year average vs. 2003

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Bottom of sheathing, 8-year average vs. 2003

Exceedence temperature (�C)

Number of hours 

2003 white roof

2003 black roof

8-year avg. 

white roof

8-year avg. 

black roof

Figure 9—Cumulative temperature histories at top and 

bottom of sheathing in structures with black and white 

fiberglass shingles exposed from January to December 2003 compared to 8-year (1992–1999) annualized 

data (Winandy and others 2000).
10

Research Note FPL-RN-0301

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Attic air, 8-year average vs. 2003

0

200

400

600

800

1000 

1200 

1400 

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Rafter, 8-year average vs. 2003

Number of hours 

Exceedence temperature (�C)

2003 white roof

2003 black roof

8-year avg. 

white roof

8-year avg. 

black roof

Figure 10—Cumulative temperature histories of rafters 

and attic air in structures with black and white fiberglass shingles exposed from January to December 2003 

compared to 8-year annualized data. 

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Top of sheathing, 8-year average vs. 2004

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Exceedence temperature (�C)

Bottom of sheathing, 8-year average vs. 2004

Number of hours 

2004 white roof

2004 black roof

8-year avg. 

white roof

8-year avg. 

black roof

Figure 11—Cumulative temperature histories at top and 

bottom of sheathing in structures with black and white 

fiberglass shingles exposed from January to December 

2004 compared to 8-year annualized data.
11

 Temperature Histories for Roof Assemblies and Wood, Wood–Thermoplastic Composite, and Fiberglass Shingles

0

200

400

600

800

1000 

1200 

1400 

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Exceedence temperature (�C)

Attic air, 8-year average vs. 2004

0

200

400

600

800

1000 

1200 

1400

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Rafter, 8-year average vs. 2004

Number of hours 

2004 white roof

2004 black roof

8-year avg. 

white roof

8-year avg. 

black roof

Figure 12—Cumulative temperature histories in rafters 

and attic air in structures with black and white fiberglass shingles exposed from January to December 

2004 compared to 8-year annualized data.