How to do Trex over garage rooftop (non living space)?


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Old 11-14-12, 08:29 AM
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How to do Trex over garage rooftop (non living space)?

Hello All,
Need some advise on roof deck.
My folks have a separate garage from living space which has a flat rooftop and our object is to make it into roof deck. We have already bought Trex 1x6 decking material.
Currently, it only has 1" plywood, we have having a small contractor install flat roof to prevent leakage and like to do decking ourselves. Now, as i understand we need to build a sleeper to install Trex over rooftop. The deck size is 22x15, it looks to be well supported but I'm still concerned about all the weight of sleepers and decking material. It has good amount of cement on the bottom sides with 2x6 supporting the roof.
Now, we are going have the contractor have a good slope so the water drains, well.
My question is what type of sleeper to built, can we use treated 2x2 so it weight less or is it must to use 2x4's. (don't want to put too much weight)?
What is the spacing needed for sleepers wood?
Does the sleeper has to be raised from the rooftop and what will be best method of doing this so?
What is good and light material for contractor to use for roof?
thanks Mac (wildzx@hotmail.com)
 
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Old 11-14-12, 05:08 PM
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2x2s will split when you shoot nails through the Trex. As far as the weight goes, you are better off paying a couple hundred for an architect, to design it for you.
 
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Old 11-14-12, 08:42 PM
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Ok, thanks for the response. I examined the garage little more today and it looks like it will be ok to handle the weight; if need i can add more 2x6's but looks ok.
Now; I'll go with 2x4's and not 2x2's. Now, do i need to raise the sleeper little bit or can i just lay the 2x4's on top of the roof (with 2" side laying on the top of roof and 4" going up) and putting the trex decking on top while screwing it in the 2x4's (in the 2" side of 2x4's). I am not planing to screw the 2x4's sleeper in the roof.
Thanks for you help
 
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Old 11-15-12, 05:34 AM
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I would still consult an architect because there are still possible drainage issues as well as structural. Not all the water will run off the Trex. Some will go between the decking. Moisture can't be trapped. I would build access doors to the existing roof drains.

As far is the 2x4s go, I would think that they have to lay flat, not on edge.
 
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Old 11-16-12, 11:16 AM
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Trex

Hello, I am a representative of Trex.
Trex, when used with a sleeper system, must be supported below its entire length and if using in a roofing application, the supports must run the direction of the pitch of the roof to facilitate proper drainage. In addition the sleeper joists must be attached to the roof structure in a manner that stabilizes the deck frame. Failure to do so may result in a poor structure which will compromise deck performance.

In areas of application where a sleeper system would be required that would not be susceptible to excessive debris buildup (examples would include covered areas such as balconies, covered porches, etc.) a minimum height of 1 �" for pressure treated joists as well as a minimum �" gap between Trex decking would be acceptable. These areas would still have to be designed to allow for proper drainage. In these cases hidden fasteners would be acceptable. However if access to the structure under the decking is required it would be recommended to use either the Universal Plastic Hidden Fastener or 2� composite decking screws. A �" to �" gap is still required when abutting walls or other fixed objects.

In all other areas were there could be excessive water buildup along with debris buildup, we would still recommend a minimum height of 3 �" for pressure treated joists, as well as a gap of 3/8�. For this application hidden fasteners would not be recommended and standard 3� composite screws would be used.

Always consult your local building code authority for proper details on roof and railing installation to the roof structure if required.

Feel free to contact me if you have any questions.

Brittany
Trex
 
 

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