# TPO roof on my front porch - why does it buckle/wrinkle when it rains?



## Robert M (9 mo ago)

Hi roofing pros...

I have no experience with membrane type roofs. It is a white "TPO" type. I don't know if this is normal or not. After a rain, the membrane looks as it is buckles. I haven't tried to see if the buckling is always in the same place or not. I get freaked out about it...mainly because right after the roof was installed, when it rained, as much rain came down under the porch as it was coming down outside. The contractor "fixed" that issue, but not sure how they did. Never had that issue again, thank goodness. But the buckling gives me a little pause. I'll try to get a picture today and add to this shortly.


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## Robert M (9 mo ago)

Here are two pictures I just took. One thing I notices is that the green slime that has built up on the roof makes me think that the buckling doesn't change much. When it rains, it seems to make it easier to see for some reason. Any and all comments, ideas, suggestions or anything else are welcome and needed!!


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## Deerfly (Mar 14, 2021)

That is normal for a mechanically attached system. The sheet expands and contracts through heating and cooling cycles. If the ambient air temp was cooler or cold/cloudy when it was installed, the first hot weather/ sun exposure offen amplifies it. The sheet will become tight in time as it goes through the seasonal hot cold cycles. 
Curious why they didn't fully adhear (glue/bond) the membrane to the substrate?


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## Robert M (9 mo ago)

Can't thank you enough, Deerfly! You explained it in a way I could understand. You are also right, it was installed in much much cooler temperatures (in late fall/early winter). Best I can tell, the end seems is where it is glued. Do most people or a lot of folks adhered the membrane all over? If that is a better way to do it, I might save some money and just have it redone. I have also read about hot mopping (which I remember when I was a boy watching it done). If hop mopping is best, I might try to find someone to do that. My thinking is a little scattered. My goal is just to get the best porch roof I can have installed so I don't have to worry for a long time. Thank you again for your reply. It means the world. Robert


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## Deerfly (Mar 14, 2021)

Fully adhered roofs cost more for a few reasons. Bonding adhesives, more fasteners for the substrate/ insulation. All equal more labor, which along with the added materials, equals more money. 
On a small roof area as shown, I would have glued it. 
When one is installing 100/1000's of squares, in say a Wisconsin/ Midwest winter. often times mechanically attached is the application method.


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