Probably installing TPO on patio awning. Not sure if the installation approach recommended is best

I have a low slope wood frame patio awning being rebuilt. It currently has T&G for the deck/sheathing which looks nice, and going to stick with this. It had torchdown before, which was painted gray, but was flaking off. I really want to stick with a nice medium gray color, so TPO seems like the way to go, and it is what was recommended by the contractor and roofer.

I just found out almost last minute the roofer says he uses 1 1/4 screws to secure it, which would blow through the 3/4 T&G, and also says he puts down some sort of insulation board underneath. (Couldn’t get a good idea what exactly he is using due to not having the best english, and not quite sure why insulation would be needed for an outdoor patio cover).

He recommended adding an extra layer of 1/2 cdx over the whole thing which his insulation would then go on top of. I’m not sure though if adding all these extra layers are actually a good idea or not though. Seems with all the extra thickness between the T&G, plywood, insulation, and membrane it might be pushing the limits of what can be hidden under the drip edge. I’m just not sure if all these extra layers is a good idea or not.

He also said the insulation could be a bit soft to walk on, but couldn’t accurately describe how much. I don’t like the idea of softness that much since I actually do go spend quite a bit of time up on the patio roof just for enjoyment and various activities, some of which require good predictable footing.

He said it is possible to just adhere it to the T&G but it wouldn’t look as good. I’m wondering if this may actually be better though to avoid all the extra layers and softness. However I do worry when it is time to reroof whether it would cause problems. Since I’m using nice T&G, I would want the roofing to be able to come off cleanly in the future.

Any advice what the best approach would be to install this?

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Install self adhered modified bitumen in a gray color. If you want some extra reinforcement, add the mid ply. Look up CertainTeed Flintlastic SA.

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Thanks. I’m researching this option now.

Do you know if it will still be removable down the road for the next time it is replaced, or would the self adhered nature make it completely stuck to the wood? Perhaps it would be best to just add like a 1/4" plywood for that?

Besides just the installation, do you think the self adhered modified bitumen is a nicer product overall to have? I’ve never seen a TPO roof on in person other than a sample square. I like the idea that it might be smooth and easy to keep real clean, but on the other hand I don’t know if that smoothness will make it look ugly like a plastic roof. I hear from the roofer TPO might wrinkle in the mid day heat, and contract at night, which doesn’t sound too nice.

TPO is too wimpy for a roof, much less to walk on…

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No roofing material is meant to be walked on or have lawn chairs drug around.

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TPO is often used for this type of deck. While he could adhere it directly to the t&g, it may not look flat AND it won’t have a fire rating if you need one. More importantly, it is a roof, not a walking surface.
If you want an easy single ply that will take traffic, consider using a PVC walking deck material like DeckRite or others. The best application would be to put 1/4" plywood over the t&g and then fully adhere the membrane. Check out their website for application. DO NOT use a mod bit for a walking deck. It, too,is a roof and not a walking surface. You’ll regret using it on the first hot day you tromp on it.


I’d just use a Peel and Stick Membrane. Pull of the Old TD and possibly the decking, replace decking with 5/16 OSB, then Peel and Stick.

This is the way to go.

No it isn’t the way to go for a walking deck. Look at the specs and warranty.


The T&G probably looks great from underneath. You should add an additional layer of plywood. If you plan to walk or use it all, the use a PVC deck membrane. These membranes must be adhered directly to really ply. No OSB is acceptable. PA peal and stick modified can be used but only with the nail base first. If you are looking only for a roof, the TPO would be best. In your situation directly to the wood with cav grip adhesive and you do not have the screws blowing through the bottom.

I have used the Flintlastic but the TPO would be best. Look for a installer that is certified with the product with the manufacturer. You can get a hold of a rep from the product manufacturer to find a good installer.
We use the 1/2 inch foam in commercial applications but your installer possibly is not experienced enough to provide all or the best options in your situation.

For a walking deck, the PVC Duradeck has amazing colors and meets all building codes for roofing and also walking surfaces. There are others but in my experience the Duradeck has the best product for waterproof surfaces.

I read three posts and finally agreed with your last one. Was that the shotgun approach?EVERYONE, TPO IS NOT A WALKING DECK. It is also inferior to PVC. I’m not even a flat roofer and I know that. I have heard good things about Duradeck.

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Hey Tileman, I am a commercial applicator, depends on the area as to whether TPO or PVC would be best. But as you said these are not walking roofs. So as I said if it is just a roof that he needs then TPO or PVC but once again depends on the area and his climate. Also because of his situation he needs to be fully adhered whether he chooses a roof or a walking deck.

If he needs a walking deck then I recommend a PVC walking deck. A modified would be the last of my options.

I guess I am uneducated on those things. I did not know PVC or TPO could be fully adhered. I thought that was just EPDM.

That is a nice looking deck for sure!

Mechanically attached is faster and cheaper…

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Thanks for the suggestions.
I’m still trying to get a roof on my patio awning.
I talked to the roofer about adhering the tpo to a thinner mechanically fastened underlayment or using a peel and stick membrane but he couldn’t do it. He claimed he would still need long nails for the metal and they would have to be 3" in from the edgh, so he said he would need 7/8 of extra plywood sheeting. Not sure why he can’t nail the metal to the 2x6 fascia board that runs all along the edge. Tried other roofers but couldn’t find one to do it.

Really interested in the self adhered modified bitumen like the Flintastic, or even better owen corning deckseal since they have the exact color of the roof shingles, however i cannot find a single roofing company that does it. The local supplier also said few companies buy it. I’m really not sure why nobody is using it.

I’m looking into the pvc walking deck but it might be excessive. Just to clarify, I don’t plan to walk on it much, just once in awhile I go on the roof to watch fireworks, jump off of it to a landing pad, watch nature. Maybe a few times a year, definitely not walking on it constantly, but the rare times I go up there, I don’t like the idea of it feeling squishy or getting dents in the insulation.