Protection from Floating Roof Deck

Hello,

My CoOp has a brand new modified bitumen roof with an aluminum gravel top. There have always been wood roof decks/terraces that sit directly on the roof and are attached to the parapet wall, and which probably contributed to the substantial leaks that we just had fixed. I know that this is not ideal, but since we are all co-owners of the building we have to allow it (there is no way to span the parapet walls and keep the joists entirely of the roof surface).

I’ve done the research and been advised on a deck system that would run sleepers directly over the roof joists and still allow for proper drainage. My question is what’s the best material to lay under the sleepers, and should that material be attached to the roof surface (with tar or some other adhesive)? Do you have any product recommendations? Responses are very much appreciated by this frustrated board member!

[quote=“nyCoOp”]Hello,

My CoOp has a brand new modified bitumen roof with an aluminum gravel top. There have always been wood roof decks/terraces that sit directly on the roof and are attached to the parapet wall, and which probably contributed to the substantial leaks that we just had fixed. I know that this is not ideal, but since we are all co-owners of the building we have to allow it (there is no way to span the parapet walls and keep the joists entirely of the roof surface).

I’ve done the research and been advised on a deck system that would run sleepers directly over the roof joists and still allow for proper drainage. My question is what’s the best material to lay under the sleepers, and should that material be attached to the roof surface (with tar or some other adhesive)? Do you have any product recommendations? Responses are very much appreciated by this frustrated board member![/quote]

First of all, what is this aluminum-gravel that is attached to the modified bitumen? Could you mean ceramic granules?

Would need photos to advise you. Sometimes an additional layer of mod. bit. is sufficient, some times a rubberized pad, and maybe even something with a Styrofoam isolator, either closed or open cell depending on weight of deck.

You can install extra Capsheet material to give you more
protection between the sleeper and the roof system. We always notch the bottom of the sleepers every 2’ and about 2"-3" by 1" high to allow`water to travel side ways if needed. We also,depending on the sleeper and size,install some dabs of elastomeric roofing mastic.
to help the sleepers from moving but still allow the membrane to flex. Installed correctly you should have no problems. You can Also make your deck into panels Large enough that you can pick them up and inspect and clean the debris as needed with out tearing the deck apart. This method is very popular in my area and works great.
Good Luck

Wow,

Thank you both for such quick responses. I must have the terminology wrong, but yes, I mean the granular surface of the new roof.

Sorry I can’t post photos, my connection is too wonky. The new roof is essentially a ‘C’ shape around the bulkhead. There will be three decks here: two private and made of wood, one communal and probably made of those recycled rubber pavers.

Great advice on the notches and elastomeric mastic. I’ll add them to the guidelines I’m creating for the new decks. What are these styrofoam isolators? Is that something that would be laid down between the sleepers, or underneath them?

Thanks again for your help, I love this website!