epdm as underlayment

[ncor]

Looking at a failed epdm underlayment for tile on an exterior 2nd story deck.
Membrane has failed and rain water migrating into habitable space below. Pretty sure epdm is not suitable for this application thought I'd double check w/ the forum. Schluter my best bet on a successful install? Framed w/ slight pitch and roof edge posts at walkway to flash in.
thanks neil

[cx]

EPDM is fine for roofing, Neil, but not if any Portland cement-based material was applied directly over it. Known problem, that.

For a tile installation over occupied space you need a primary waterproofing layer (your EPDM), then something to protect that and provide drainage, then a properly installed mud bed, then a secondary waterproofing layer suitable for your tile installation. Schluter Systems does make the products and specifies such a system, as do others.

The only single layer waterproofing method for that installation I'm aware of is using Noble Deck from the Noble Company. That requires a minimum slope of 1/4" per foot in the deck framing and a layer of CBU or deck mud over the decking, as a minimum.

We'd need to see some photos of your application to comment much further. Lot of other consideration in an installation like that and a lot of liability.

My opinion; worth price charged.

[ncor]

Mir-Kote and Troba If the underlying joists are within deflection parameters. Believe I will be in a sticky wicket with the deck penetrations and may consider a full pan broke and pittsburgh seamed. Any thoughts on boots for the railing posts or 4x4's that are bullet proof?

[Davy]

I've used Mercrete, its a paint on membrane with a fabric. The railing connection on the deck would get painted over with several coats. Flashing has to be done too. Not sure what you have for flashing now.

[ncor]

By the look of it these guys thought roofing mastic was the answer followed by drip edge. Tomorrow I'll see what the joist spans are.