Weatherproof above basement garage
Hello. Has anyone had a condition where there is a basement below a covered open porch? What is wanted is a 24’x24′ basement garage with a covered porch on top of it. So, I am wondering about proper water proofing on the roof/floor and the best material to construct the roof/floor out of. My first thoughts are concrete planks spanning the 24′ with a rubber membrane then a type of floating deck or maybe an adhered outdoor tile. Any advice greatly needed. Thanks.
Do you want clear span? This is the most expensive solution.
If you can accept posts, then 4" concrete on a metal deck.
You're going to need an engineer. This is not a DYI/ wing-it project. The engineer can provide 2-3 preliminary solutions to assign cost and design priorities.
At grain may be needed. That's a lot of runoff.
For waterproofing, Laticrete has a spec for what's involved:
Depends on how much $ you want to spend, your expectation of how long you want before repairs/maintenance issues arise and if the garage below is climate controlled. A lot of different ways it can be handled. The simplest/most affordable would be to build a wood frame flat roof (1/12 pitch) roof above the garage and install a floating deck above it or a better option a deck built above the flat roof.
If you want something that is maintenance free and will last the life of the home. I would install a hollow core slab above garage. Grout the seams of slabs as usual. A layer of geo textile fabric on that. Then a layer of EPDM. Followed by another layer of geo textile fabric. Finally, a poured slab on top of that with 1/4” per foot slope. Can apply any finish you choose over the concrete or leave as is.