Plywood deck over a rubberized roof

[professional_amateur]

Hey guys,

Our master bedroom has a sliding door that walks out to a flat section of roofing. It was obviously planned on being used for a deck but was never finished/built. The roof is covered with rubberized panels. I saw a recent video about using plywood for flooring, and I'm wondering if I could use this as a cheap deck floor.

My idea would be to purchase enough external plywood to cover the surface, then cut the boards into 8inch slabs. I'd sand the boards and then stagger them to use as the deck flooring. Looking for feedback on this process.

I'm also wondering if I could simply drill these boards directly to the roof, without using an underlying frame. Framing would add a lot of weight to the roof, and it also would also make it so that you'd need to step up from the sliding door - the roof is pretty much flush with the base of the door jam now.

Just looking for the cheapest, easiest way to put something down so that we can use the space as a deck. If cutting the plywood into planks doesn't make sense, could we just lay full boards down instead? Most of the area will probably be covered by a large outdoor carpet, and we'd stain/paint the plywood.

My only other concern is in regards to the rubber matting - would drilling into this cause any issues with moisture potentially seeping into the roof?

Thanks in advance for any suggestions.

 

[Snoonyb]

What living space is under the roof, what is your location?

 

[mabloodhound]

Do NOT nail/screw through your rubber membrane! It will leak.
You need to lay sleepers down (on the flat) and then fasten your deck boards to them.
Carpet is not a good idea; use boards (like mahogany) and keep them spaced apart so water can drain.

 

[professional_amateur]

Do NOT nail/screw through your rubber membrane! It will leak.
You need to lay sleepers down (on the flat) and then fasten your deck boards to them.
Carpet is not a good idea; use boards (like mahogany) and keep them spaced apart so water can drain.

Thanks for the tip- I was worried about that...

What do you recommend I use as sleepers? I'll admit I wasn't familiar with the term, but after a quick search, it appears that there are lots of available options (wood, plastic, concrete, etc.). What about using something like pressure-treated 2x2 boards laid parallel to the roof's water drainage?

In addition, how could I attach these sleepers to the rubber membrane? Or would the weight of the deck boards be enough to hold everything in-place?

@Snoonyb - the roof is above our mudroom and carport—we can't afford for moisture to seep through.

 

[Snoonyb]

Thanks, that and the relative climate zone, will illicit a variety of responses.

 

[mabloodhound]

PT 2x would work fine. You want them laid so that they allow water to run off the roof and not act like a dam. You can use construction adhesive to hold them in place. When you nail or screw your top boards on make sure the nail/screw is short enough to not go through the 2x.

 

[professional_amateur]

PT 2x would work fine. You want them laid so that they allow water to run off the roof and not act like a dam. You can use construction adhesive to hold them in place. When you nail or screw your top boards on make sure the nail/screw is short enough to not go through the 2x.

Thanks for the suggestions, they are super helpful. Now I have another issue- the roof was built to drain to one side, which meany deck boards would run perpendicular to the side of the house, which I think would look a bit off. Is there any way I can use the PT 2x sleepers running perpendicular to the drainage direction without causing water to dam? Or what else might you suggest? I've attached a few pics to help articulate.

 

[mabloodhound]

Personally, I don't think it would look bad. However, you could cut 1/2" deep by 1" wide notches every foot on the underside of each sleeper. But I think that's more work than needed. Lay some boards out on the deck, perpendicular to the house and get a 2nd opinion.

 

[professional_amateur]

My wife agrees- she thinks it'll look fine with the boards running perpendicular. I guess I have my answer! Thanks for all the help. I would have made a huge mess of things if I hadn't asked first and started drilling directly into my rubber membrane!

 

[nealtw]

My wife agrees- she thinks it'll look fine with the boards running perpendicular. I guess I have my answer! Thanks for all the help. I would have made a huge mess of things if I hadn't asked first and started drilling directly into my rubber membrane!

You want hand rail that will attach to the sides of the fascia and not thru the roofing material.

 

[stadry]

you can't stop water but you can manage it - for ***** & giggles, look at westcoat's alx system,,, might be helpful

 

[Jeff Handy]

You might need to be able to remove some deck boards every few years, to be able to hose out or blow out debris that will build up down there.
Especially if there are any big trees nearby.

Debris will block the water from flowing off properly.

The biggest trouble can happen at the rubber roof edges.
You probably want to clean up and reseal all the edges before laying down any sleepers.

 

[oldognewtrick]

It doesn't look like a rubber roof, it looks like a modified bitumen system. The two adhesives and sealants are different.

A solution to debris getting between the deck boards is covering the sleepers with screen before the decking installed.