Bitumen roof if the membrane is in good condition your contractor can simply cut an x shape into the blister to.
How to repair foam roof blisters.
What to watch for roof coating blisters in ponding water areas are due to moisture permeation from above.
Cut the blister out using a razor knife bread knifes work the best.
With proper care and repair your foam roof can virtually last forever.
Foam roofs take a beating from our phoenix sun.
In this first picture it identifys a golf ball size blister.
Membrane roof cut away the membrane that has lost adhesion replace any wet insulation with like material and replace.
The polyurethane will need to cure before you seal the repair.
Use a putty knife to pry up the blister.
Roof coating blisters in areas of adequate drainage are usually coming from below.
Inspect the damaged area for any moisture and continue cutting away damaged foam until only strong and dry foam remains.
Moisture trapped in spray down foam due to deterioration or loss of protective coating.
Use your polyurethane caulk to fill in the opening where the blister was removed.