Sources of Flat Roof Failures - Inspection Guidance
- Procedure code:
- Hspg Prepared For Nps - Sero
- Thermal and Moisture Protection
- Membrane Roofing
- Last Modified:
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This standard includes guidance on identifying sources of flat roof failures by looking at specific problem areas.
Inspect Exterior walls of building:
- Settlement cracks
- Stained or displaced flashing or drainage facilities
- Efflorescence on the wall - this may be a sign of leaks in the coping or parapet above.
Inspect interior walls of building:
- Damp or stained walls
- Chipped or discolored paint
Inspect underside of roof deck:
- Wood deck: rotted or warped boards
- Concrete or gypsum deck: cracks and stains; spots ofrust may also appear on a concrete deck from wet reinforcing rods in the concrete; a gypsum deck may spellas a result of leaking water.
- Metal deck: rust spots
Inspect roof surface:
- A sprung board in a wood deck. Identified by sharp indentation of roof surface, often caused by a broken board.
- A noticeable "give" in the roofing under weight.
- Cracks in membrane.
Make sure drains are flush with the roof and free of debris.
- Change in original slope of roof
- Standing water
- Blocked drains and/or gutter
- Cracks, gaps or damage to coping joints
- Loose, torn or missing flashing
- Improper bond between base flashing and edge of mat or between counterflashing and wall
- Flashing that is not turned up enough potentially allowing water to back up, stand against the wall and leak down into the roof deck
- Rust on flashing or lack of protective coating on corrosive metals
- Inspect roof at least twice a year and inspect after any severe storms:
- Debris accumulation and vegetation growth
- Deterioration of the surface and membrane
- Deck deflections (sometimes from structural problems)
- Ponding and tensile splitting of water weakened felts and/or membrane
- Ice formation and resulting membrane damage
- Positive drainage
- Wear spots at curbs and penetrations
- Ruptures, bare spots, splits, metal flange splits, deteriorated felts
- Warping, cracks, splits, slivers, cupping and rot
Note priority of defect
- (i.e. none, minor, major, complete failure.)
Note changes from last inspection.
- i.e. none, minor, major,
- Note what changes occurred