Without photos or more details it is hard to guess where the leak is and how to stop it.
Leaking concrete roof deck.
Waterproofing tiles and marble slab can be laid over the concrete slabs with water seal joints to stop water leakage from a concrete roof.
If the deck and floors are at different elevations, you probably do not and the deck is independent of the interior floors.
Simple application and fast drying.
One of the most obvious signs that your roof deck may have introduced a structure leak into your home is water stains or discoloration on your walls or ceiling.
Don't replace your worn out leaking deck or balcony, resurface it with armortop or balcony one coat!
Roofs & gutters q & a this site uses akismet to reduce spam.
Build a deck over it to shed water?
I have a 100 year old garage with a leaking slab roof, connected to a leaking tunnel slab.
On top of the foam goes an elastomeric coating which keeps the foam protected from uv light, and granules which protect the coating.
Concrete is not water proof (liquid or vapor)or really even water resistent.
If the floor slab is continuous with the inside floor, the leakage is probably around the projecting deck (top, sides or bottom).
If an area feels spongy, it’s a sign of rot and a clue to a compromised membrane.
Check the entire roof surface, look out for ponding water, and inspect the plumbing lines.
The whole thing is formed in one continuous piece.
Take a walk around your deck and feel for soft spots under your feet.
This is your best bet for maintaining your deck while also bringing an end to those troubling garage leaks.
Once the waterproofing membrane is laid, drying out of the structural slab will mostly take place from the underside of the deck.
The upper layers have an abrasive sand in the epoxy, giving you some surface resistance.