Making A Flat Roof A Deck?

Grumpy

When a customer says to you "I have this flat roof I want to use as a deck" how do you respond? What type of system do you recommend? Assume they are setting no limitations on material or budget.

pgriz

We have done a few of these. We usually use the most appropriate material for the roof surface itself (torch-on membrane or equivalent), then build a platform on which the deck surface itself is installed. This way, the deck doesn't look like a roof, and there is no foot traffic damage to the roofing material. I know some people install granulated top sheet and claim it is strong enough to support foot traffic, but what if someone puts a chair on this and starts rocking back and forth? You've got a tear in no time.

Grumpy

Pgriz, we usually do a double layer of the modified bitumen torch down. If we do a single layer, we at least install a double layer where the "deck" sleepers make contact with the roof.

If you do use a deck type system it is important that the deck floats and is not fastened to the roof. Also it's important to be aware that the pressure of the deck sleepers on the roof is a common cause of leaks. This is why we do the double layer at the sleepers.

Tom hay was telling me abotu a roof system he installed as a deck a few months back and I wish I could remember the link to the pics. He coated the roof with some kind of material (adhesive maybe?) then sprinkled granuals of some sort on the roof for traction.

pgriz

You are, of course, perfectly right. Our decks do float, and in fact we use rubber pads to support the deck and hold it separate from the roofing material. As I said, we've done a few and so far no call-backs.

Grumpy

Yeah these roof decks are the things I think about when it rains hard. No call backs here either but I fear they are coming.

Imhotep0357

Hey guys, this is my first time posting. I'm a young GC out of Florida, and I'm about to build my first deck for a client who is already starting to take apart and analyze my wall sections for the roof deck system. As for the sleepers, do you turn them on edge or lay them flat? Is the double layer of bitumen a good idea with all of the humidity that we experience down here.

thom

I've done a few. I like the double modified then an asphalt impregnated expansion strip pad(the ones you use with concrete) under the sleepers (flat, not on edge).

You've still got to insure that you are not overloading the roof framing system.

naptown CR

Make sure you have slope for anything you put on the deck at least 1/8 per foot. If they want to do it for a low budget there are a few walkable roof surfaces out there. they look like a vinyl sheet good and are very durable. Also you don't have to worry about sleepers and debris building up between the roof deck and the decking and holding water as it drains toward the edge. The products that come to mind are Duradeck and Deck-king. Just don't use anything thinner than 60 mil. The last roof deck I did was over a torch down roof. I set strips set sleepers on as a double layer. screwed 5/4 timber tech to the sleepers. This was done as a change order and when I got to the county to revise the permit they gave me a really hard time about uplift on the deck as it floated. even there was only a 1 1/2" gap at the lower end for drainage. This was a couple of years ago and I did not know about the duradeck at the time. I ended up paying about 6.00 sq ft for the torch down and additional strips and a fortune for the decking. Could have done the job in duradeck for 8.00 a sq ft and saved a lot. I believe the Deck-king carries a 20 year warranty and is code approved in most jurisdictions as a walkable roof.
Oh yeah as posted above this check your roof framing as it is probably not built for a deck loading. Around here our roof design loads are 20# sf and decks are required to be 60# sf.

Imhotep0357

Yeah, I just got off the phone with my truss supplier, and he thinks that my load is about 65 psf per the FBC. Looks like I'm going to have to get some wood I's to make my 25' span...I'm hoping no deeper than 16" @ 24 o/c. I'm going to research the Duradeck...sounds like a money-saver!

wellbuilthome

Ive done many torch down roofs with sleepers and they don't seem to hold up for the long haul .
In the traffic ares the rubber get squashed to nothing and starts to leak in 7 to 10 years . We even cut strips of roofing to double up layers and tried 2x6 sleepers .
Now, i like a build up of Epoxy and 3 layers of 16Oz glass cloth. We roll on a high build primer and 2coats of none skid or rubber DURA BAK .
I make the deck posts out of cedar and glass them in and coat them with epoxy You can get the glass and epoxy on EBay in 5 gallon buckets and large rolls . My largest was 12x 20 . Ive done lots of master bed room walk outs 6x6 .

naptown CR

I tore one out that was done this way several years ago. This thing was rotten through the deck and into the rafters. Client wanted mahogany decking so we did double torch down and sleepers. i still like the duradeck or deck-ing

apehangeralfy

Seal-O-Flex... pink, fabric, pink. Then you can use there top coat and seal or tile directly to it. When done correctly I have not seen one fail.

Torch down is not allowed under a 1/4 pitch here so you have to use an approved "deck" system...

Hand Bangin

On my personal deck I used two layers of modified and then came back with Hydro-Stop 4 layer system. I had to replace all the rotten soffit underneath the deck which was a mess. I installed the new roof first to make sure it was water tight......now with the new roof, deck and soffit underneath it seams to be holding up very well. I may have overdone it a little, but I figure spend a little extra now to prolong the life of it.

Hope this helps.

dougger222

My father and I have roofed a few flat roofs for builders which had decks built on top. One we didn't like as they had an opening in the middle for the water to drain. The idea was they didn't want any gutters on the front of the house. We made it work but it was a pain.

On my own home we recently did a flat roof/deck on the balcony off the master bedroom. The builder put down rubber roofing and decking on top which leaked in a few spots on the ceiling underneath. My idea was to put a roof system down that never needed to be done as long as I owned the house. Here's what we did,

First we put a layer of 1/2 inch plywood over the rubber roofing. After walking on it it was decided another layer of 1/2in plywood would help firm up the deck. We removed the hardi board siding against the wall and cut up the hardi board on the four pillars to allow our roofing product to lap up on the walls/pillars 6 inches. Then we put a layer of Winterguard on it and base sheet on top of that. Next we put down smooth torch. From there my tile guy took over and put down slate tile which turned out amazing. My father came back and did the shoe around the base of the pillars. Now waiting on my wife to pick out a railing system.

Gilby

I lay duro-last and it is probably your best bet to put a deck on. It is durable and best of all its completely clean. Its never dirty. You mechanically fasten it down and heat weld all the seams together. We use this all the time for that sort of thing.

dougger222

My Uncle worked for a roofing outfit that was certified to install Durolast. He said the company on average charges $1,000 per square labor and materials for new construction.

Just looked at a roof that had it on the roof above the indoor pool.

Isn't this just another of the many thin rubber like flat roofing products with a life expectancy of 10-15 years?

J-Peffer

Flat roofs seem bad enough, but then people want to walk on them too!

Just does not seem like it can last too awfully long, and really could make it a expensive repair to fix if it starts to leak or needs to be replaced.

Ed the Roofer

Duro-Last is a Hybrid copolymer pvc alloy, which means it is a white membrane reinforced with a polyester scrim.

It's standard mill thickness is stated as .040 mills, but is actually closer to .037 mills thick.

If you have no sharp objects that will rest on it, and if the tech using the hot air welder knows how to seam weld properly, the roof will last it's warranty length. They offer a 15 year unlimited or a 20 year pro-rated after the first 10 years warranty. Oh, it does come in other colors too, but they are not your typical order, such as Grey, Tan and a new one that I can not recall at the moment.

The main problems deflected at Duro-Last installations, are the sloppy bagginess that some contractors do not know how to pull the wrinkles out and also the continual turn over of their Quality Control Inspectors.

Also, since the sheets are pre-fabricated to the size of your roof order, up to 20 squares large, the 5 foot wide panels are pre-seamed with a dielectric welding process at the manufacturing and fabrication facility.

There are many rumors from other contractors, that state that the attachment at this dielectric weld, when pulled as taut as necessary to achieve a tight looking roof surface, have split apart. Also, spider-webbing cracks have been commonly reported to occur after the installation has weathered for some time.

I did not ever see either of those problems exasperate themselves on probably around 2,000 installations that I did with that brand of product, but the tearing at the dielectric weld potential did cross my mind.

Ed

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BULLHART

I prefer a ashpalt hybrid for this one. Maybe a 3 ply built up with a Modified Cap.

wellbuilthome

I haven't had any callbacks on my glass roof jobs yet . The first one was done in 1997 . I have been back to change the color on one and replace the none skid. It still looks like new . I mite try the dura deck next time .
John