I’m planning to build a deck atop a rubber roof. The roof has a minimal pitch of somewhere around 3%. I’ve been told to use foam sleepers beneath the wood deck to prevent damaging the rubber membrane. How is this typically done? does the foam run the entire length of each joist or can i put it under posts? how do i keep the deck from sliding off the roof in a gale. I’m not comfortable with simply sitting in on the roof. Any and all advice appreciated.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
The batch plant is your partner in getting high-quality concrete on your job site.
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Check out http://www.bisiondecksupports.com.
We do a lot of Decks/patios on top of EPDM roofing, the paver system with the above product is one of the best systems out there. Maybe I should post some pictures of the decks were doing in the city 20 stories above.
Were paying about $20 a sq.ft in the heart of the city, but the roof top patios add big time to sales!
http://www.bisondecksupports.com/You spelled it with an extra 'i' in bison
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Thanks for the correction, need to find the photo of the paver system with built in planter boxes, it's the big thing around here with the city dwellers.
i'm pretty sold on the foam sleeper idea. 1" polystyrene is cheep and easy and i believe it will protect the rubber membrane. i guess i'll have to glue the foam to the rubber and then glue the joists to the foam and tie down to the fascia/rafter ends where i can. i'd sort of like to run the deck joist perpendicular to the roof slope / rafters but maybe that complicates things too much. but running deck boards parallel to the slope would be helpful if ever there was a leak. i could just unscrew a few boards to gain access to the problem area. anyway, i'm still paranoid this thing is gonig to slide / blow off the roof eventhough everyone is saying it's weight will keep it in place.would it be acceptable to run the joists parallel to the roof slope on top of the foam sleepers and then run bracing every 16" between those joists and then screw the deck boards into the bracing? i have limited clearance but that would get my deck boards going in the right direction. if i put a 2x4 between the foam and the joists that would provide a ledger for the bracing to sit on... any thoughts?
I've run them both ways, just leave breaks in the foam when crossing the drainage, or my way - dado out notches for drainage.I rip tapered sleepers when running with the pitch.Be carefull what glue you use on the EPDM. Some glues can eat it alive. EPDM is not compatible with anything bituminous. I am not sure what would work well without disolving the polystyrene either. Maybe spray foam - Enerfoam
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
i'ld like to run the 5/4 deck boards parallel to the slope. should i put nailers between the tapered joists or can i just run my joists across the pitch? i'm not sure how i would support the joist if they ran them across. should i rip them to match the roof angle and space out the foam below to allow for drainage. which is the better approach in your opinion? thanks
If you are going to use foam, ( I wouldn't for the reasons Dino gave - it will break down after time and will probably squeak to beat the band too) then it would be easy to rip it to different thicknesses laying under the sleepers, and allow say a foot every three or four feet open for drainage, which can alternate locations
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Do you have any experience mounting posts (like 4x4) to flat roof decks. I am thinking of lagging knife blade (custom made) post bases to the roof and flashing over them but I was hoping for some better ideas before I go ahead.
What type of roofing material will the post be mounted on?
epdm over adventec/ 2x10 framing
Most Epdm manufacturers have a spec on how to do posting. We have used this product with metal post on Sonoguard decks with good results.
http://www.bestmaterials.com/detail.aspx?ID=11225
What we do is have the roofer leave an extra 10-15% of EPDM in scraps to glue to the PT sleepers for a wear layer cushioning the roof
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
The foam will eventually crush under load and cause problems. Cedar sleepers with a strip of EPDM rubber cemented under them for anti-chafing will do just fine.
Run the sleepers parallel to the slope and make sure you leave drainage weeps through the lower rim-sleeper (and if you don't need a rim-sleeper at the bottom of the slope, you'll be better off without one).
I know what you mean about fearing it will slide or blow off the roof if it isn't nailed down somehow, but it won't. There is almost no vertical sail area on a deck sitting right down on a flat roof, so normal wind won't bother it. If a hurricane or tornado gets under it and pushes up on the deck boards, it won't matter if it is nailed down anyway--it's gonna go.
But hurricanes and tornadoes are considered 'acts of god'. Unless you are specifically contracting to build a 'hurricane proof' or 'tornado proof' structure, you can't be held liable.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
Dinosaur is right. If the wind is strong enough to lift your deck off, that will be the least of your problems.