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Recommendation for water proofing of multi level wood deck

6K views 8 replies 3 participants last post by  1985gt 
#1 · (Edited)
I have an existing 1000 s.f. deck in Austin Texas. Two levels with stairs between. 300 sq. ft is covered (eventually screened in) the rest exposed. I will modify it to add 1/4 on 12 slope for drainage.

I am looking to deck it out and cover with a flat roof membrane, then cover with sleepers and ipe. Workshop, storage, and playroom to be added underneath.

I am wary of using torch down due to fire risk.

TPO, EPDM, SA Modified?

Should I not be worried about using torch down?

Suggestions/Recommendations?

Simeon
 
#2 · (Edited)
You might check into Wahoo Decks. They have a waterproof aluminum flat joist system that you can put under the ipe. You can google them. I've dealt with Wayne up there, and he's very helpful. I have only used their railing, and it's really nice. I've gotten samples of the joist system and it seems like it would work well. Don't know if it would work for you, but you might check it out.
 
#3 · (Edited)
Thats pretty cool I must say. Thanks for the tip. I will look into it as an option.

Update: Looks a lot more expensive versus adding plywood, membrane and sleepers.
Not sure I can justify the extra expense. after googling the product, it looks like its about $8-$10 a sqft for the EZ version and 15$+ for the other version.

Update 2: Got an email back from the manufacturer with pricing
DryJoist is 16$ / Sq.ft. + shipping
DryJoist EZ is 12$ / Sq.ft. + shipping
 
#6 ·
A lot of the folks in the deck forums are saying torch down. If I do go that route what do I need to spec as a separation between plywood and torch down to do it right and avoid fires? Do they all say torch down because its what they have done for years and years or because it has some advantage over the other approaches?
 
#7 ·
Probably a bit of both, Torch roofing is a bit tougher then say EPDM. With that being said we have installed countless EPDM roofs under walk out decks. Some have wood/composite and some have had concrete on top. I've never once had a problem.

In the past I have done them with putting densdeck on top of the plywood. Once of the things to consider is that if the plywood is nailed down the nails could pop up, that's why I like to use densdeck. Another product to use would be 1/2 HD ISO. I also tend to like to use 60 mil EPDM and 6" seam tape.

I think a lot of people who torch down will put the deck runners directly on the roofing, even with torch downs this isn't a good idea, always put some kind of separator between the deck runners and roofing. 2 reasons really, one is puncture resistance two would be the fact the deck my or may not move at different rates as the roofing system.

We stopped using torch down 20 or so years ago mostly because of the liability. In fact most of the larger commercial companies around here stopped doing it years ago because a one of the larger companies a bigger then us just about completely burned down a very important building. Almost put a 50 year old company out of business.

*If* I were to do one I would nail a base down including up any ways. Then torch a base layer down then a cap sheet.


What I would spec would be a 60 mil EPDM over a 1/4 or 1/2 densdeck or 1/2 HD ISO fully adhered. Make sure they leave enough extra material to providing you with padding for your runners. Generally we will just cut 6" wide pieces of EPDM.
 
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