Built-Up Roofing - Page 7

6.13 Cold Weather Application

6.13.1 Roof applications below 45°F (7°C) require special measures to ensure proper performance of the roofing system. JM strongly recommends that the following guidelines be followed when applying built-up roofing systems in cold weather:

A. Use extra care to ensure that any moisture is removed from the deck surface. The presence of moisture may cause poor adhesion or skips in the mopping asphalt, which in turn can entrap moisture within the roofing system.

B. Store materials in a heated warehouse or closed and heated trailer immediately prior to installing.

C. Do not overheat the asphalt. Insulated asphalt lines and insulated roof-top equipment should be used. Set up job site equipment to minimize the distance between asphalt heating source and application point.

D. Do not mop more than 4' (1.22 m) ahead of the roll. Embed the rolls into the hot asphalt immediately.

E. Squeegee all fiber glass ply felts to ensure adhesion.

F. Install only as much roofing material as can be completed and covered in one day.

G. The use of temporary roofs should be strongly considered if construction schedules require roof applications in cold or rainy weather.

6.14 Temporary Roof Coverings

6.14.1 At times, an owner or general contractor may require the building be closed-in when the weather is not conducive to good roof construction, or the roof area may have to be used as a work platform during construction. In the past, this situation has led to phase construction which has resulted in premature roof failure. When a completed roof system cannot be installed in one operation, it is recommend that the following procedures be observed:

A. Nailable Decks:

1. Apply one layer of approved JM base felt, lapping the felt 2" (51 mm), and nailing 9" (229 mm) o.c. along the lap and 12" (305 mm) o.c. through the center of the sheet. (Sheathing paper should first be installed on wood board decks. Sheathing paper is not required on plywood decks.)

2. Mop one ply of approved JM ply felt in ASTM D 312, Type III asphalt and apply a glaze coat of 10-15 lbs. per square (0.49-0.73 kg/m²) of the same grade asphalt.

3. When the permanent roof is to be installed, inspect the roof and remove all damaged and blistered areas. Apply a layer of approved JM base felt nailed through the temporary roof and into the deck as the first layer of the roofing system. As an alternate, a layer of approved JM roof insulation may be mechanically fastened (with appropriate fasteners) through the temporary roof into the deck.

4. Proceed with installing the appropriate permanent roof specification.

B. Steel Decks:

1. Apply a minimum layer of approved JM insulation, inadequate thickness to the steel deck using the appropriate mechanical fasteners.

2. Install two plies of fiber glass felt, both set in hot Type III asphalt to the insulation.

3. Finish with a 10-15 lbs. per square (0.49-0.73 kg/m²) glaze coat of hot, Type III asphalt.

4. When the permanent roof is to be applied, inspect the roof area. If the insulation has not been damaged and is dry, remove any blistered or damaged felt. Solid mop a layer of insulation board to the temporary roof with hot, Type III asphalt. Then apply the permanent roof system. In some regions of the country, a JM base felt may be machine spot-mopped or mechanically attached with appropriate insulation screws and plates directly to the sound temporary roof, followed by an asphaltic roofing membrane. Consult a JM Technical Service Specialist for acceptability.

5. If the temporary membrane and/or roof insulation has been excessively damaged, remove all unusable material and replace.

C. Non-Nailable Decks Other Than Steel:

1. Prepare the deck as would be done for a permanent roof.

2. Solid mop two plies of approved JM fiber glass ply felt in hot ASTM D 312,Type III asphalt.

3. Finish with a 10-15 lbs. per square (0.49-0.73 kg/m²) glaze coat of ASTM D 312, Type III roofing asphalt.

4. When the permanent roof is to be installed, inspect and repair all defects in the temporary roof. Clean the surface of the temporary roof and prime with JM Concrete Primer if the surface is unusually worn, and proceed with the installation of the permanent roof.

5. As an alternate to step 2 above, spot mop an approved JM base sheet using a mechanical spot mop machine. Next, solid mop one ply of an approved JM ply felt in hot ASTM D 312, Type III asphalt. When the permanent roof is to be installed, remove the entire temporary roof, prime the deck as required in the "Roof Deck" section of this manual, and proceed with the installation of the permanent roof.

6.14.2 The decision as to whether or not a temporary roof is to be left in place, is a judgment factor that must be made by the building owner or his representative. Although a JM representative may make suggestions in this area, JM will not be responsible for any problems that may develop with the roofing system due to the fact that the temporary roof is left in place.

6.15 Protected Roofing Membrane Systems (PRMA)

6.15.1 General Information: All general information contained in this Section and the current JM Commercial/ Industrial Roofing Systems Manual shall be considered part of these specifications.