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Home > Main Index > Markets > Construction Applications > Perlite Concrete > Reroofing and Roof Renovation > R-Value1, U-Factor2 And Deadload Table3

Perlite Concrete for Reroofing and Roof Renovation
Prepared by: The Perlite Institute

R-VALUE1, U-FACTOR2 AND DEADLOAD TABLE3
BASED ON 1:6 MIX RATIO, 24-30 PCF PERLITE INSULATING CONCRETE
2 INCHES OF
PERLITE CONCRETE
OVER POLYSTYRENE
THICKNESS IN INCHES
DEPTH OF CORRUGATIONS STRUCTURAL
CONCRETE 4 INCHES
26 GAUGE 15/16 INCH 24 GAUGE 1-5/16 INCH 22 GAUGE 1-1/2 INCH
R U D.L. R U D.L. R U D.L. R U D.L.
0 3.9 .187 5.87 4.1 .177 6.65 4.1 .180 6.85 3.1 .216 4.00
1 7.9 .106 6.20 8.2 .103 6.98 8.1 .104 7.18 7.2 .115 4.33
2 11.7 .075 6.28 12.0 .074 7.06 12.0 .074 7.26 11.0 .080 4.41
3 15.6 .058 6.36 15.9 .058 7.14 15.8 .058 7.34 14.9 .061 4.49
4 19.4 .048 6.44 19.7 .047 7.22 19.7 .047 7.42 18.7 .049 4.57
5 23.3 .040 6.52 23.6 .040 7.30 23.5 .040 7.50 22.6 .042 4.65
6 27.1 .035 6.60 27.4 .035 7.38 27.4 .035 7.58 26.4 .036 4.73

FOOTNOTES:

  1. R Values are expressed as 0F.ft2h/Btu.
  2. U Factors expressed as Btu/h.ft20F. Includes air films and roofing.
  3. Dead Loads include weightof metal, polystyrene and perlite concrete roof insulation. Dead loads of structural concrete are not included.

NOTES:

  • Insulation values are for summer conditions, heat flow down. To calculate winter conditions, heat flow up, substract 0.39 from the R-value, then add 1.5 for air films and roof, and divide into 1 for the U-value.
  • U factors are based on series-parallel heat flow caluculations defined in the ASHRAE Handbook of Fundamentals and on test data by recognized, independent test laboratories. Thermal conductivities of roof deck components are based on 400F mean temperature except perlite concrete which is based on 750F.
  • Perlite concrete properties are bsed on constant thickness insulation. For sloped insulattion, calculate average thickness.
  • The U factors shown are calculations based on thermal conductivity data derived from laboratory testing of dry materials in accordance with ASTM Specification C 177. The values shown are intended only as guidelines. Actual insulation performance for all materials and systems is affected by design of building, environment, and installation, and will be lower than calculated values.

Information given herein is from sources considered reliable, but no guarantee of accuracy can be made or liability assumed.  Your supplier may be able to provide you with more precise data.  Certain compositions or processes involving perlite may be the subject of patents.
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