Flat roof defects Flashcards
1
Q
What are some common asphalt flat roof defects?
A
- Blistering
- Cracking
- Ponding
- Slumping
2
Q
How does blistering of asphalt flat roofs occur, and what does it lead to?
A
The trapped moisture vaporises and forms a blister in the asphalt. Eventually, repeated cycles of vaporisation result in the perforation of a blister and further water ingress.
3
Q
How does blistering of asphalt flat roofs occur, and what does it lead to?
A
- Asphalt is susceptible to deck movements, particularly following ageing and exposure to UV light.
- At low temperatures, the material is very brittle and can fracture.
- Embrittlement can result from overheating during laying.
- Can create a point of water ingress.
4
Q
What is the issue with water ponding on an asphalt roof and why does it occur?
A
- Changes in level of the roof deck can lead to the reversal of falls away from outlets and to ponding.
- Debate as to whether or not ponding is bad for asphalt roofs. If a leak does occur there is a greater reservoir of water available to penetrate the building.
