Question with tiling tub flange area and water collection

ShtRnsdownhill said:

if that link was a picture it didnt work, many times the grout line at the tub will develop a fine crack as the grout really doesnt stick to shiny surfaces, it sticks between the tiles as the sides of the tiles are rough..so the silicone is an extra, I would have used a phenoseal or tub and tile sealant that matches the grout color and sealed that bottom with the sealant and then grout up to the sealant after it dried, but clear over grout is ok, there are many ways to do it correctly..

Click to expand...

sorry about that, don't know why i am having problems with the pictures.

The contractor put grout between the tile and acrylic tub. then he put clear silicone over that grout line.

It seems most people say to have no grout and use caulk.

Others say to use grout, because the caulk traps moisture, if it ever gets through.


In my case, we have used reguard. the tub has a has 1.25" lip. Is it ok to use caulk, even though it might trap moisture?

Or is it better to just have grout and the lip should be enough to prevent water from going behind the wall?

Here is another attempt at a pic:
http://tinypic.com/view.php?pic=339ooj6&s=9#.VraqKlJBEcM

http://tinypic.com/view.php?pic=j76ybb&s=9#.Vraq4VJBEcM

http://tinypic.com/view.php?pic=2m81lr5&s=9#.VraraVJBEcM

WhatRnsdownhill said:

water is not suppose to go through the tile if tiled properly....

Click to expand...

The tile, no. But the tile grout, water will go through. This is guaranteed.

Folks assume a tiled surface (vertical or horizontal, doesn't matter) is impervious to water. It is not, because the grout lines "leak". For this reason, when constructing (for example) a shower wall, you either need to use an impervious backer (e.g. Kerdi, DensShield, etc) or use a CBU backer with a waterproofing liquid (e.g. Redguard or Hydroban over Durock or Hardiboard).

Water (more specifically, moisture) that gets behind the tile has three ways out: evaporation back through the grout, collecting and draining down into the pan (fiberglass base) or pan liner (mud base), and finally *but not desirable* wicking into the surrounding framing. The last leads to mold and structural degradation.

Showers without an impervious backer or waterproofing liquid basically rely on the CBU simply drying out into the wall cavity. While the CBU itself is not prone to mold, it does hold a lot of water and will eventually become saturated. Older methods of shower construction have the CBU attached to the framing over a vapor barrier (poly sheet or 15# felt). While a "barrier", it is still perforated in many places by attachment screws or nails, and the now-saturated CBU simply "leaks" into the supporting framing.

For the above reason, modern shower construction is such that you first need to accept that the grout lines will leak, and thus the conclusion is to ensure that the moisture goes no farther "in" than the thinset under the tile. The only way to accomplish this is to use an impervious to water surface directly under the tiles -- Kerdi, DensShield, Redguard, HydroBan, etc. -- and make sure that at the bottom of everything there is a way to capture water from behind the wall tiles and direct it to the drain (again, using Shluter's shower system, or a traditional mud base sloped rubber membrane which comes up the walls at least 4-6").

wrooster