Water or air bubbles on roofing surface

 November 23, 2020. 3:11 PM

The presence of water or air bubbles on waterproof covers is a fact that can occur in some particular circumstances, such as in the case of thermal insulation and the absence of an adequate vapour barrier. In the latter case the vapour may rise up and meet the membrane (notorious for being scarcely breathable to water vapour) and bubbles can form, at low temperatures, which then condense into water. Another problem can occur when the concrete is not left to set long enough and being waterproofed immediately it holds on to the water still present inside it.

1. What should be checked?
Check the presence and working order of the water vapour barrier.

2. What are the functions and presence of air vents for?
Check the working order and presence of air vents as they are always useful with or without an insulating panel.

3. What should be done to the bubbles?
Any bubbles should have a cross cut into them and then, after having waited for them to evaporate/dry out, a patch of the appropriate material should be applied.

4. Why are the bubbles more obvious when it is hot?
The bubbles may be more obvious when it is hot; this is due to the increase in the amount of water vapour compared to the amount of water.

5. What should be checked inside the building?
Check that the inside of the building does not have any damp marks; which might not necessarily be due to a leak but due to dampness present in the foundations. As this humidity cannot be released externally (because the membrane is not very breathable) it may manifest internally.

6. When does condensation happen?
Condensation normally only happens at certain times of the year, or when there is humidity and particular temperatures. Therefore the problem occurs in cycles throughout the year and often can be caused by thermo-igrometric phenomena and not by seepage.