The following repair process is applicable to several different repair situations that require installing a BUR membrane patch to return a BUR membrane to a watertight condition.
Typical BUR Membrane Repair Procedure:
- To promote thorough adhesion of a patch, it is essential to begin by preparing the surface. Remove debris, contaminants, aggregate or loose surfacing from the surface of the membrane or flashing to be repaired. The area to be prepared should extend a minimum of 450 mm (18 in) beyond the perimeter of the defect to provide a clean work area on which to install the patch and tie it into the existing roof membrane.
- On gravel surfaced roofs, carefully spud the aggregate free from the surface and sweep clean.
- Prime the surface of the membrane with asphalt primer and allow to dry.
- Where plies are removed from the membrane, install the same number of plies (a minimum of 2 plies) in hot bitumen or cold-applied adhesive. Extend the bottom ply at least 150 mm (6 in) beyond the area to be repaired and each succeeding ply at least 75 mm (3 in) beyond the previous ply. When using hot bitumen as the method of application, take care to maintain the bitumen at its proper EVT. As an alternative, on asphalt BUR membranes only, modified bitumen membrane sheets may be installed by torch application, in hot asphalt or suitable cold adhesive. When using hot asphalt as the method of application, use Type 3 asphalt and take care to maintain the asphalt at 204°C (400ºF).
- To reapply the surfacing, embed gravel in hot asphalt or roof cement or apply a surface coating compatible with the existing surfacing. Liquid applied coatings should be installed in accordance with the coating manufacturer’s instructions, which may include a waiting period.
Tears or Punctures
- Inspect for water that may have leaked into the roof system. If water leakage has occurred, open the membrane and inspect the insulation and deck for damage. Remove and replace wet or damaged insulation and repair or replace the deck as required.
- Follow the Typical BUR Membrane Repair Procedure described above.
Fishmouths and Buckles
- Expose and prepare the surface in the area of the fishmouth or buckle as described in the Typical BUR Membrane Repair Procedure.
- Carefully cut the ridge, wrinkle or fishmouth with a sharp utility knife, remove debris (if any) and inspect for leakage. If leakage has occurred, inspect the insulation and deck for damage. Remove wet or damaged insulation and repair or replace the deck as required.
- Remove the buckle, wrinkle or fishmouth to an adhered area.
- Prime the surface of the membrane with asphalt primer and allow to dry.
- Complete the repair as described in the Typical BUR Membrane Repair Procedure above.
Blisters
The decision whether to cut out and remove, patch over to reinforce or simply monitor blisters is a judgement call. In general, smaller blisters that are keeping water out should be left alone.
Some characteristics that may determine the need to repair blisters are:
- Excessive loss of gravel or other surfacing.
- Membrane deterioration.
- Blisters in laps which have reduced lap coverage.
- Blisters that have breaks.
- Blisters that have fatigue cracking.
- Blisters that occur in areas of high traffic.
Should it be determined that blister removal is necessary, the following steps should be used:
- Prepare the surface in the work area as described in the Typical BUR Membrane Repair Procedure above.
- Carefully cut and remove the blistered material until good adhesion of the membrane is reached. If water leakage has occurred, remove wet or damaged insulation and repair or replace as required.
- Complete the repair as described in the Typical BUR Membrane Repair Procedure above.
Splits
- Prepare the area of the split as describe in Typical BUR Membrane Repair Procedure above.
- Cut out loose felt from the split area. Inspect for water that may have leaked into the roof system. If water leakage has occurred, open the membrane and inspect the insulation and deck for damage. Remove wet or damaged insulation and repair or replace the deck as required.
- Extend the split approximately 300 mm (12 in) further in length by cutting through the membrane 150 mm (6 in) at each end.
- At the new ends of the split, make a T-cut (a cut perpendicular to the split) approximately 150 to 200 mm (6 to 8 in) long.
- Prime the surface of the membrane with asphalt primer and allow to dry.
- After the primer has dried, cut a piece of granular surfaced modified bitumen membrane cap sheet approximately 225 mm (9 in) wide and of sufficient length to cover the split from end to end. Center the sheet of material over the split, granule surface down, to serve as a slip sheet.
- Complete the repair as described in the Typical BUR Membrane Repair Procedure above.
Bare Spots, Alligatoring, Surface Erosion
On a gravelled roof, a bare spot is an area without aggregate in the surface flood coat, with no other defect in the area of the bare spot.
To repair, clean the area to receive new aggregate.
Prime the surface of the membrane with asphalt primer and allow to dry (if roof cement is used, priming is usually not required). Apply a heavy pour of hot bitumen or thick layer of roof cement to the primed area and embed new gravel.
Surface erosion is caused by wind and water. The protective gravel coating is washed or blown away leaving the felts bare and exposed.
The area can be repaired by first sweeping and cleaning the affected surface and priming.
A new layer of gravel is then installed in a pour coat of asphalt. The surface must be thoroughly dry and clean for any surface repair to be effective. If, however, the underlying felts have deteriorated, new felts must be applied. In this case, the defect is treated as a puncture or split.
Alligatoring occurs when the bitumen coating is hardened (oxidized) by sunlight. This hardening causes the asphalt to crack. The bitumen will continue to harden with exposure, the cracks become progressively deeper until the surface takes on the appearance of an alligator’s hide, hence the name. If allowed to continue, the asphalt may curl and break away from the surface, exposing bare felts below. When this happens, the felts are subject to wetting, rot and other forms of deterioration. Repair requires the removal of excessive bitumen thickness, if present, and the application of primer, reinforcing felts, and coating materials such as clay and asphalt emulsions. A new pour coat of bitumen is unlikely to be helpful since the bitumen below will continue to shrink and crack.
Loose Wall and Base Flashings
Cut out flashing materials that are loose, wrinkled or displaced until reaching solidly adhered material. Inspect the flashing for possible water leakage. If water leakage has occurred, open the membrane and inspect the insulation and deck for damage. Remove wet or damaged insulation and repair or replace the deck as required.
- Repair the BUR field membrane and BUR flashings as described in Typical BUR Membrane Repair Procedure above.
- Fasten the top of the base flashing to the wall or curb. Fastener spacing should be 150 mm (6 in) on center maximum. Termination bars and fasteners may also be used to secure the top of the base flashing.
- Seal the fasteners and the top of the base flashing with a layer of vertical grade roof cement and embed one ply of fabric.
- Topcoat with a second layer of vertical grade roof cement.
- Add counter flashing as required for a permanent repair.
Pitch Pans
- If the filler material has cracked, pulled away from the side(s) of the pocket or is below the level of the top of the pan, remove loose or damaged sealant material, dirt, foreign material and/or water.
- Apply a thin continuous film of appropriate compatible primer to the inside walls of the pitch pan and the sides of the penetration and allow to dry.
- Top off the pitch pan with a compatible pourable sealer, crowning the filler material to provide for positive drainage of moisture around the penetration.
Drains
If leaks are suspected at interior drains, ensure the drain is free-flowing, then check (water test, if necessary) the drain bowl and plumbing from the underside of the deck (if access is possible) to determine if plumbing parts are cracked, if condensation is a problem, or if the plumbing joints are leaking.
If there are no problems evident, inspect membrane-to-drain bowl interface for voids/ problems.
- Check clamping ring bolts and snug-down in sequence to tighten clamping ring. Drilling and tapping of drain bolts and receivers to allow the replacement of the clamping ring bolts if they are seized may be necessary. Repair or replace all drain components that are missing or are broken.
- If leak persists, cut back and remove the existing membrane flashing, clean drain flange removing damaged membrane and plastic cement, apply new layer of plastic cement.
- Reinstate the membrane and complete the repair similar to the Typical BUR Membrane Repair Procedure above.