I have noticed that on my RV’s TPO roof, which is now 13 years old, there are a couple of large bubbles that have appeared on areas that are not near any entry points. When walking on the roof I do not feel any spongy sections but do have these bubbles that have appeared. I have inspected all vents and do not find any loss of sealant or indications of leakage. Also, the bubbles do not appear to have any holes within the roofing material. Should I be concerned? Do I need to replace the roof soon? Or can it wait a bit until the rest of the roof needs replacement? The roof appears to be in good shape other than the bubbles. Your suggestions would be invaluable insight into this apparent issue. Thanks. —Steven the Canadian Glampur, 2010 Fleetwood Jamboree GT
The composition of your Jamboree Class C is a sandwich design of an exterior layer of TPO, luan plywood, block foam insulation with perimeter framework and some cross members, and interior luan plywood with a decorative covering of either wallpaper, hair cell fabric, or padded vinyl. Each layer gets a spray coating of adhesive and then the entire roof goes into a vacubond machine with draws all the air out and applies pressure to both sides.
What I believe is happening to your TPO is a separation of the material from the luan due to the adhesive weakening or letting go. This can happen if the spray area was not thick enough or due to a temperature issue at the time of application. However, the bubbling or delamination would have started much earlier than 13 years later.
I have also witnessed cases where the luan has separated as it is made up of layers of thin wood material, as well. It can blister or peel and would create a bubble as you describe. I don’t believe it is anything to get really concerned about or require a new roof. However, it does warrant visual inspection more often.
The reason for the bubble is if the adhesive became weak or the luan blistered, the TPO pulls away from the substructure during temperature changes as it expands and contracts without resistance and would create a wrinkle or bubble. It is mostly cosmetic until it starts to spread or the TPO gets a puncture or tears, then it will become a moisture penetration issue.
To fix or not
Typically, I would just make sure the roof material is cleaned and conditioned periodically and watch to see if it gets worse. What you can do is cut the TPO with a razor knife about one inch at the center of one of the bubbles so you can slightly separate the material and inspect the substructure. If there is nothing there that would look like moisture or other severe damage, apply some TPO adhesive under the material and place a weighted 2×4 on the seam. Then cover the slit with EternaBond or self-leveling lap sealant made for TPO. This will help verify that it is just an air bubble and is cosmetic only.
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