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Concerns with Various Types of Flat Roofs While there are many commonalities between the
various generic roof types, each roof type has distinct aging characteristics and develops different defects. The defects
an inspector will find in built-up roofing will be different from those found in EPDM rubber. We have listed below several
common conditions that affect the long-term performance of a roof, regardless of roof type, as well as differences to look
for in the three most common roof systems:Defects Common to All Low Sloped Roofs- Underfilled pitch pans
- Clogged
or restricted drainage
- Debris, sharp objects
- Chemical exhaust, particularly oil and solvents
- Collapsed,
wet or damaged roof insulation
- Insufficient fastening of sheet metal copings,
gravel stops, counterflashings
- Poorly sealed flashing terminations
Built-Up
Roofs- Loss of felt surfacing, gravel, aluminum coating, or asphalt surfacing
- Felt erosion, loss of plies
- Membrane
aging, alligatoring and brittleness
- Membrane damage, punctures or cuts
- Membrane defects, blisters (especially broken blisters), splits, ridges
- Flashings aging, splits, open laps, racheting or slippage
- Poorly sealed flashing terminations
| Modified Bitumen Roofs- Blisters, especially at laps
- Loss of surfacing, especially SBS modified bitumen membranes
- Open laps
- End lap shrinkage (loss of overlap at roll
ends)
- Membrane aging, surface crazing, pitting
- Membrane damage, punctures or cuts
- Flashing defects,
blisters, open laps, slippage
Single-Ply Membrane Roofs- Single-ply
membranes can be made from a number of different chemical formulations. The following defects are occasionally found on most
all of them.
- Open membrane laps
- Membrane damage, punctures, cuts
- Inadequate attachment, ballast
or membrane displacement, shrinkage or wind damage
- Membrane aging, crazing,
stiffening or brittleness
- Flashing defects, open laps, loss of attachment
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