Waterproofing a covered porch floor

Hello all,
I’m restoring a covered porch on a 1908 4 square. At some point a garage was added under this porch. So what I need is advice on a waterproof membrane to be applied to the plywood subfloor. I’ll need to install sleepers on top of this system to nail the t&g porch floor down. Should I use torch down roll roofing or a rubber product like Everguard TPO? What might be the best way to secure the sleepers?
Thanks for any thoughts-

APP modified, EPDM, or a good PVC product.
I prefer the Modified, multiple plys are very nice. :wink:

I agree with Axiom as far as the durability of the APP, which means the torch down variety of Modified Bitumen products and also if within the budget, use a multi-ply system of it.

Also, I would suggest designing the decking in removable sections, in the event that some patch work would be required. It will save you thousands of dollars down the road.


Everguard tpo is not a good idea a great product but not for this application if you are going to use a tpo or pvc product find a I.B installer and use there 80 mil sheet.But i think the other guys where right a 2 ply mod bit is a good choice.

I agree mod bit holds up to traffic better than a single ply but other manufactures also make a 80 mil tpo/pvc product not just IB.

How about a BUR with the sleepers set in asphalt?
That is pretty good also.

I know there are other 80 mil sheet hell if you want to get down to it try a 90 mil sheet.I apply only single ply and mostly pvc,tpo the reason i said ib is for the warranty on a home.

Ya a lifetime warranty is hard to beat. Id like to hear the claim call in 80 years.