20-22643 - Laserfiche WebLink

Browse Search

ROOF OESIGN CONSIDERATUOUS Perimeter Half Sheet Table •R-Value —Thermal Resistance:The number of degrees difference between Number of Number of Number of two surfaces(energy difference)that is required to obtain an Building Building EverGuard® EverGuard® EverGuard® energy flow of 1 BTU through a 1-square-foot(0.0929 sq m) TPO 60" PVC 60" TPO 72" sample of a given material thickness in one hour. Width Height (1.5 m) (1.5 m) (1.83 m) —The R-value is the reciprocal of the C-value.The C-value Half Sheets Half Sheets Half Sheets represents thermal conductance and depends on the thickness of the material. 0-34' 1 1 1 (0-10 m) —Thermal Resistance applies to an actual thickness of a material, and as such is a quantitative physical property that can be used <200' 35-100' 2 2 2 for determining insulation requirements. (61 m) (10-30 m) >100' Formula Calulations:Install half sheet throughout the •Reflectance (30 m) perimeter and comer region.The width of this region is defined as the least of the following two measurements:0.1 x building —A measure of the%of solar energy that is reflected away from >_200' width or 0.4 x building height a surface. (61 m) any height Note:The minimum perimeter width is 4'(1.2 m).The width is —Dark materials absorb more heat from the sun and can be up defined as the narrowest dimension. to 70°F(210C)hotter than a reflective white surface given the same outside temperature and conditions such as wind speed, location,etc. The perimeter area,as defined in the above table,may be adhered •Emittance as an alternative to using half sheets.When adhering the perimeter area,the number of insulation fasteners must be increased in —A measure of the infrared radiation emitted from a roof surface. these areas;refer to the insulation attachment section for adhered Unlike reflectance,infrared emissivity may not be affected by membranes to determine the proper insulation attachment dirt or discoloration of the surface of a material. pattern.In all cases where the perimeter area is adhered,the membrane must be mechanically fastened where the perimeter The following references provide useful information regarding area(the adhered area)meets the field roof area.This attachment energy efficiency: will prevent pooling of the adhered perimeter area.Refer to the sheet lay-up details in the mechanically attached system section •ASHRAE Fundamentals Handbook for requirements on the installation of these half sheets.Note: —Provides detailed design calculations and material energy When designing for wind loads,ensure that the proper building transfer information utilized by mechanical engineers in the classification(closed,partially closed,or open)is used if the design of heating,ventilation,and air-conditioning systems. building has large openings(i.e.,docks with large loading bays, etc.).Improper classifications can result in roof attachment failure —Suitable for complex energy evaluation considerations such as caused by designing to lower loads than actually exist for the solar heat gain,exterior shading,total building envelope, building in question.Factory Mutual Approvals attachment requires building usage,and lighting. the formula calculations. Important Note:Most states/jurisdictions have not adopted ASCE ®NRCA Roofing Manual:Architectural Metal Flashing 7-16.If you are in an area that requires ASCE 7-16,please contact Condensation and Air Leakage Control,and reroofing GAF for assistance. —Provides a simplified method for determining the amount of insulation necessary to construct an energy-efficient low-slope ENERGY EFFICIENCY roof system. Thermal transmission standards have been established by building —Provides a simplified method for determining the energy codes for most buildings.Roof insulation installed above the cost savings resulting from the installation c additional roof deck is a practical means of achieving the necessary energy roof insulation. efficiencies.In addition,the use of white-colored reflective —Suitable for most roofing-related energy evaluations. membranes can reduce the heat load on air conditioning equipment,as well as provide a moderating effect on the temperature in proximity to the building. •The NRCA Energy Wise Roof Calculator —Provides a simplified method for determining the amount of •U-Value insulation necessary to construct an energy-efficient low-slope roof system. —Thermal Transmittance:The number of BTUs(energy) —Provides a simplified method for determining the energy that pass through a assembly inI-squar one our with sq.m.)sample of cost savings resulting from the installation of additional a total material assembly in one hour with a temperature roof insulation. difference between the two surfaces of 1 F(/9 Q. —Thermal Transmittance applies to an actual total material —Suitable for most roofing-related energy evaluations. assembly,and as such is a quantitative physical property —Go to www.enerpvise.arca.net that can be used to represent the overall thermal performance of a system. 16