1. Roof deck must be solid sheathing, either plywood or original plank board construction. Any large voids must be replaced or covered with sheet metal.

2. Installation may be applied directly over rigid insulation board.

3. Overlays are allowed over original built-up roofing if the roof is in reason able condition.

a. New material may be applied directly over smooth surfaced or mineral surfaced cap sheet.

b. Gravel or rock surfaced roofs should be swept clean and covered with minimum 1/2” insulation board material prior to installation of the new roofing.

4. Severe ponding water should be corrected. (Puddling of water on flat roofs is acceptable.) Ponding water issues must be evaluated no later than the pre-inspection or the in-progress inspection.

1. A slip sheet of Kraft paper or other appropriate material is needed on areas of the deck containing a large amount of residual asphalt.

2. Nail one layer of base sheet over the entire roof area.

3. Nails should be square head, ring shanked type long enough to penetrate 3/4” into or through the deck. Shorter nails may be used to minimize penetra tion of the deck where visible.

4. Nailing pattern is typically 9” along each edge with two rows staggered 18” apart down the middle of the sheet.

1. Apply modified bitumen roll by use of torch, hot asphalt, or cold process adhesive as required by manufacturer’s specifications.

Application of “torch down” modified bitumen system

2. The entire roll should be fully torched, mopped, or glued so that all seams are fully adhered.

3. Edge laps should be 2” minimum and end laps should be 4” minimum.

1. Mineral surfaced modified bitumen does not require any further surfacing.

2. Modified bitumen may also be surfaced with asphalt emulsion, Aluminum coating, or other approved elastomeric coating.

3. Some applications allow leaving modified bitumen unsurfaced. IRCC recommends surface treatment of all modified bitumen roofs.

1. May be reused if in serviceable condition. When roofing over an existing roof, flashings should be lifted and installed with the new roofing.

2. Flashings shall be sandwiched between two layers of modified bitumen. Flashing flange shall be nailed securely over the first layer of modified bitu

Flashings set on modified bitumen

3. The flashing should be primed with an asphalt primer prior to installation.

4. Plumbing pipes may be sealed to the flashing with flashing tape, rubber collar,or plastic cement.

1. All vertical angles should receive a cant strip if the curb is 2 or more inches high.

2. Penetration flashings may be reused if in serviceable condition.

3. All sheet metal penetration flashings shall be primed and sandwiched between two layers of modified bitumen. Flashing flange shall be nailed securely over the first layer of modified bitumen.

4. Top of base flashing should be nailed securely to prevent slippage.

5. Perimeter edges should be finished with sheet metal or 3 course mini mum with webbing and plastic cement compatible with modified bitumen.

1. Properly surfaced roofing material may be turned up under existing counter flashing and nailed to prevent slippage.

2. If the existing wall was removed, the roofing material may be turned up a minimum 6” into the wall cavity and new stucco or siding installed over the roofing material.

3. Properly surfaced roofing material may be turned up 6” on an existing wall, nailed to prevent slippage, and sealed with a minimum 3 course using plastic cement compatible with modified bitumen and webbing.

1. All large equipment blocks and/or sleepers shall be securely mounted to the roof deck and flashed into the roof membrane in an appropriate way.

2. Conduit and pipe blocking should not be sealed to the roofing membrane.

I. BUILDING DEPARTMENT INSPECTIONS:

1. Pre-inspection of roof overlays should be required especially where ponding water is a concern.

2 In-progress inspections should include spot checks of decking, roof application, and flashing installation.

3. Final inspections should be done while the roof is being finished.