The Deck Expert answers readers questions for only $25.00 Recently one reader asked us this question about his tiled deck.

“I saw your site on the web.

I have a tiled exterior deck. I have discovered it was not hot mopped before laying tile.

Obviously, it leaks.

I have been advised to use sealants but they don’t waterproof.

Jay Q Los Angeles

Our Answer

Dear Jay,

Sadly there isn’t any sealer that will waterproof the tile. Sealers will help reduce moisture absorbed into the tile and down through the mortar bed, but will never succeed at actually waterproofing it.

A proper waterproofing system for a tiled deck is installed prior to the tile and mud bed being set. A pre-sloped substrate is waterproofed with a membrane suitable for tiling over, then a drain board is set on the waterproofing to allow water that does get through tile/grout/expansion joints to evacuate to a drain or an edge.

Hot mop waterproofing is pretty much a method of a by-gone era and isn’t used much anymore. Your deck I’m afraid will need to be completely stripped down to the framing and rebuilt. If you want to put tile down again, you’ll need to hire the best craftsmen available, using the best industry standard methods for framing/substrate and the waterproofing and tile assemblies.

You should expect that this will run an average of $70 to $100 per square foot for a complete rebuild, a little less if you go with a walking deck system that looks like tile. The picture above is a decorative faux tile walking deck system from Pli-Dek.

Do your job right the first time, get the right information here at DeckExpert.com.