What causes bubbles on EPDM rubber roofs?
The most common reason for bubbles showing on an epdm roof are vapours from Contact Adhesive:
Contact bonding adhesive is solvent-based and is crucial for adhering the rubber membrane along upstands and the roof deck perimeter.
The contact adhesive must dry to a state where there is no transfer when touched before membrane application. This prevents vapours from forming bubbles beneath the membrane. Although these bubbles may dissipate over time these may expand and contract depending on the ambient temperature.
In severe cases, re-bonding may be necessary if the adhesive wasn't allowed to dry properly.
Expansion of trapped air within the roof structure:
This bubbling phenomenon occurs primarily in warm deck roof designs where EPDM bonds directly onto either a timber deck or insulation.
Moisture-laden air trapped beneath the insulation can expand when heated by the sun, causing bubbles to form along board seams. Typically, the membrane contracts back into place as the roof cools in the evening. To prevent this, ensure the roof structure beneath the insulation is dry and that insulation boards are snugly fitted together. Any gaps should be filled with expanding foam adhesive to prevent air entrapment.
Installing a vapour control layer within the roof can also mitigate membrane lifting caused by expanding air.
If you would like to learn more about installing an EPDM roof, why not attend one of our training courses EPDM Training Course Details
