Waterproofing Upper Deck


Seven years ago we renovated our house inside and out. Our stucco contractor (hired by our GC) installed a Pli-Dek waterproof deck system that ultimately failed which was recently removed. The deck is quite large, 739 sq feet, a drawing is attached. The deck is now plywood as shown in the photos. We have an outdoor living space with a stucco ceiling underneath and, fortunately, it is the dry season here in Sacramento. We have contacted several contractors without much luck (even commercial contractors for referrals). One roofer came out to look at it and said he would do a TPO but never heard back from him. It seems as though EPDM isn’t used here in N Cal or Sacramento area or, at least, we can’t find a roofer who does it. One roofer that was referred to us is booked up until the end of the year. So, we need some professional advice for waterproofing this deck. My husband and I are big diy people, but feel EPDM installation is for an experienced pro. We are open to a liquid rubber product if that would work. We have done countless hours of research. Our #1 idea is 60 mil EPDM with a snap together composite patio tile on top. With snap tiles, the deck base would be easily accessible if there was ever a leak in the future. One more thing, we’re considering selling next spring, so we economically want the deck waterproofed and to look good. Thank you for any advice.![Deck 1|281x500]

![Deck 4|690x387](/uploads/roofing/original/2X/d/d8f7bd8dcab1182f3dfd8f2ba1d2767f953c5df9.jpg)(/uploads/roofing/original/2X/e/ef28858e44c8e549a2749c4461520cdb9eb72f26.jpg)


EPDM can be purchased in the Sacramento area but would be special ordered. Your project would call for a fully adhered EPDM system. TPO would work also. Both products are not designed to be a walking deck, so you most certainly would need a walking surface.
You might also consider a PVC walking deck system like DeckRite. That could be installed over the plywood and would be a walkable finished surface. Send me a PM and I might be able to find an installer for either.


Thank you! We did hear back from the roofer who would do TPO and his quote was over $6500. Then it would be another $2000+ for patio tiles. It’s too much for us. We made a decision to find a walkable rubberized waterproof deck system and not go the TPO or EPDM route. My husband talked to a roofing distributor near us and he recommended PermaDri walkable deck system for plywood. Do you know anything about PermaDri?


Sure do…there are a ton of walking deck coatings on the market.
Another one is Pacific Polymers systems. The thing you have to consider
is the thickness of your plywood deck (should be 3/4" to 1-1/8" Plywood)
and fastened securely. The joints must be “taped” with polyester fabric
and the system applied. Follow carefully the application rate, more is
not better. If you are going to do this yourself, good luck. I
actually sell a walking deck system to roofing distributors in Northern
Cal. so I know a lot about the systems. I’d still recommend the PVC


Thanks Don. If money wasn’t an issue, I think we would be using a PVC product like DeckRite. From our research, PVC systems are the most expensive option. I just measured the plywood on the deck and it’s 1-1/8". It will definitely need to be fastened more securely. We’re planning on troweling the seams with PermaDri Rubber Patch as recommended in their application data sheet and using polyester fabric on the entire surface. Is that overkill? Is there a walking deck system on the market that you would recommend? I’m grateful for your advice.


I agree with Don, this isn’t something that can be done inexpensively.

The walkable PVC is designed exactly for what you want.

The prices you quoted don’t seem too bad to me, walking decks are pricey.


Whatever system you use, get professional help. The deck to wall tie in will be tough and may require cutting the stucco and installing metal or reinforcing fabric to bring the membrane up 3-4". As it looks now you only have about an inch which means you will have to rely on caulking to seal off the membrane, which is not a good idea. Same problem with the door sill… I don’t know where you got your price info on PVC, but I think it is a little off.


The best advice I can give you when dealing with a flat roof as don stated is use a professional. No matter what product you choose there are many techniques / tricks, especially when dealidealing with flashing and wall tie ins that take field experience to prefect and I personally wouldn’t want to try them out for the first time in my house. All my experience is in the northeast so very different climate than where you are but I’ll throw out my experience. The company I am with has been doing commercial and high end residential roofing for over 75yrs and has torn off every imaginable walk on roof deck system. The only system we have found to be tried and true in our wet snowy climate is a 3 ply modified bitman ( mechanically attached ventilated base sheet, 1 layor smooth STA modified, 1 layor granulated GTA cap sheet) then covered with soft surfaces interlocking pavers.