APP Bitumen Modified - Page 7

7B.16.6 JM makes no claims as to the quality of these products nor their performance when exposed on the roof. See the product warranty supplied by the fabric manufacturer.

7B.16.7 When pavers are used as ballast, the pavers must be placed on supports or pedestals. These supports or pedestals can either be commercially available products or 6" (152 mm) square pieces of JM DynaTred Plus (to give a minimum 1/2 " [13 mm] air space). These supports should be located at the intersection of the corners of the paver blocks, such that where the four corners come together, all rest on the same 6" (152 mm) square piece of DynaTred Plus or pedestal. The 1/2 " (13 mm) air space between the pavers and the insulation will allow moisture vapor to vent to the atmosphere. If the moisture is not allowed to vent to the atmosphere, the top surface of the insulation will begin to absorb water and the thermal performance will be reduced. ROOF AREAS THAT HAVE PAVERS IN DIRECT CONTACT WITH THE INSULATION ARE EXCLUDED FROM COVERAGE UNDER A JM ROOFING SYSTEM GUARANTEE, INCLUDING THE THERMAL OVERLAY PORTION OF THE GUARANTEE.

7B.16.8 The use of pavers in high traffic areas, to and around equipment and other maintenance areas, is strongly recommended.

7B.16.9 It is the owner’s and/or specifier’s responsibility to determine if the building structure can support the required amount of ballast and still meet the code design requirements for anticipated dead and live loads (including snow, wind, etc.).

7B.16.10 Decks (PRMA)

7B.16.11 Pre-cast slabs and pre-stressed "T" or "TT" decks require a minimum of one layer of approved JM roof insulation as a leveling course prior to the installation of the roof membrane.

7B.16.12 For lightweight insulating concrete, gypsum decks, etc., consult a JM Technical Service Specialist for Specifications and Guarantee information.

7B.16.13 For information on roof deck requirements not mentioned here, refer to the "Roof Decks" section of the current JM Commercial/Industrial Roofing Systems Manual, or contact a JM Technical Service Specialist.

7B.16.14 Warning: Extruded polystyrene insulation is combustible and may constitute a fire hazard if improperly used or installed. It should be adequately protected. Use only as directed by the specific instructions for this product. This material should NEVER be exposed to an open flame or other source of ignition.

7B.16.15 All roof deck systems over which the protected system is installed should provide an adequate fire barrier for the extruded polystyrene insulation.

7B.16.16 For proper protection of plastic foam in storage, consult the National Fire Protection Association (NFPA) standards or the authority having jurisdiction.

7B.16.17 Installing Ballasted PRMA Roof Insulation Over Modified Bitumen Roof Membranes

7B.16.18 The following are general recommendations for installing ballasted PRMA roof insulation over modified bitumen roof membranes.

7B.16.19 Insulation: Place extruded polystyrene roof insulation directly on the membrane with channel side down. The insulation boards should be tightly butted together. The maximum allowable gap between boards is 3/8 " (9.5 mm). The boards shall be installed to within approximately 3/4 " (19 mm) of all projections and cant strips.

7B.16.20 For multi-layer installations, install subsequent layers, unattached over the first layer. Stagger all joints in relation to the underlying layer. The bottom layer in multi-layer applications must be at least 2" (51 mm) thick and as thick or thicker than the top layer.

7B.16.21 Fabric: Loose lay an approved fabric over the extruded polystyrene roof insulation, with all joints lapped a minimum of 12" (305 mm). There should not be any end laps within 6 feet (1.83 m) of the perimeter. The fabric should extend 2" to 3" (51 - 76 mm) above the stone at the perimeter and at penetrations.

7B.16.22 Wetting the fabric is helpful in holding it in place on the insulation until the ballast is installed.

7B.16.23 Ballast: Apply the correct size ballast at the rate of 1000 -1200 lbs. per square (10 - 12 lbs. per sq. ft. [48.8 - 58.6 kg/m²]), over the fabric, as the fabric is being laid out in the field of the roof. For a width of 4 feet (1.22 m) at the roof perimeter or penetrations, install ballast at a rate of 20 lbs. per square foot (97.6 kg/m²) or pavers at a rate of 22 lbs. per linear foot (32.7 kg/lin. m). If pavers are used, the fabric is not required. Pavers must be placed on pedestals. Pedestals can be either commercially available products or 6" (152 mm) square pieces of JM DynaTred Plus.

7B.16.24 Ballast should be washed 3/4 " (19 mm) gravel or crushed stone, with fines (smaller than 1/2 " [13 mm]) accounting for not less than 10% or more than 60%. This gradation is similar to ASTM D 448, Gradation #57.