Grout for exterior tiles

Diy help please · 08-26-2012, 01:33 PM

A few years ago I had some ceramic tiles installed on my deck/carport. The deck is the top of the carport and with the height comes lots of 'give' in the structure. The grout has cracked and water leaks through the surface. The grout needs to be replaced with something that is waterproof and will keep it bond with the tiles. Any recommendations are very appreciated.

wkearney99 · 08-26-2012, 02:11 PM

You're saying you've got tile on top of a surface that surface that has a lot of flex in it? Then you're going to forever have tile and grout cracking problems. Tile and grout are hard materials that must be installed on a rigid base. You need to eliminate any flex in the flooring under the tile, otherwise it's just going to keep cracking. Nothing you put in the grout seams is going to solve your problem until you eliminate the movement.

Meanwhile, be sure this structure is actually strong enough to hold up that tiled deck. A regular deck is unlikely to be strong enough to have the several hundred pounds of tiles added to it.

JazMan · 08-26-2012, 06:23 PM

Bill , (WKearney99) is absolutely correct. For some reason many people think that installing tiles is going to make the installation waterproof since tile are used in wet areas. NO! Neither tile or grout is going to stop water from going into the substrate and below.

You need to remove everything until you get to the framing and start there.

Jaz

wkearney99 · 08-26-2012, 06:38 PM

Yeah, lots of folks don't understand that tile and grout are not going to make a surface water tight. They do resist water penetration but they're not waterproof, not by a long shot. To a degree you'll get more with the underlying thinset or mortar. But if you want real waterproofing then you'd want to use a membrane or sealer like RedGuard.

I'm guessing you're thinking it's the cracks in the grout that are letting water through, and that's correct. If there weren't any cracks then you'd be less likely to get water through them. But not because of the grout doing the sealing. No, it's the mortar underneath that would be adding to it. When you see cracks on the surface it means the underlying material is cracked. The cracks in the grout are just a sign of what's gone wrong underneath.

As much as you don't want to hear it, the only way to address problems like that is to pull up the tile and start over with a stable surface and a proper installation. Using a membrane like Ditra would probably help, but you'd still have to eliminate the flex even for that to have a chance to keep a surface solid enough for the tile and grout not to crack.