How to waterproof a tile bathroom floor?


Old 08-02-11, 10:35 AM
Thread Starter
Join Date: Dec 2009
Location: SC
Posts: 65
Received 0 Votes on 0 Posts
How to waterproof a tile bathroom floor?

I would like to waterproof the tile floor in the bathroom of a 50 year old home. This is to prevent any additional waterdamage to the subfloor/floor joists. I tried several applications of sealant product but water still leaks through to the crawl space. I installed a shower door but the tenants seem to be unable to prevent water from getting on the floor when exiting the shower.
Sponsored Links
Old 08-02-11, 10:59 AM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,585
Received 94 Votes on 83 Posts
Ceramic tile?

If so, it doesn't take sealer, it's the joints that are the problem. Have you caulked the joint between the shower and the tiles?
Old 08-02-11, 11:00 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 21,113
Received 3 Votes on 3 Posts
The grout is not waterproof...even with a sealer...and of course edges can't be completely sealed, guess you know that. The only way I know would be to rip it all out and install some sort of product like Kerdi.

Are you sure it's actually coming through the tile floor or is it leaking under the edge of the tub, from the drain, or somewhere else?
Old 08-03-11, 04:51 AM
Thread Starter
Join Date: Dec 2009
Location: SC
Posts: 65
Received 0 Votes on 0 Posts
Yes I have run a bead of silicone b/w the tub base and tile floor. Pretty sure it is coming from the floor just outside the tub. I poured a small amount of water (4oz) on the floor in the suspected area and by the time I could crawl under the tub in the crawl space(apprx 5 mins), the majority of the water had leaked through to the ground. I have also checked under the tub while the shower was running and did not witness any leaking. From the underside of the bathroom floor, the leak location corresponds to the area just outside the tub where one would step when coming out of the shower/tub)
Old 08-03-11, 12:02 PM
Join Date: Jan 2006
Location: USA
Posts: 3,521
Received 8 Votes on 8 Posts
Tile waterproofing is done underneath the tile, not over the top. That being said, its very difficult to fully waterproof a bathroom floor. The water needs to go somewhere, so it'll make its way to the perimeter of the room and run out there, or run out by the door, or run out by the closet flange, etc. Bathroom floors are generally not waterproofed.

The best defense, is to contain the water inside the tub/shower. Caulking, a new shower door, etc. and people taking care to contain the water as best as possible.

If 4oz of water is just pouring thru the floor, something isnt right. You should be able to wipe most of the water up after a few minutes. How is that floor constructed?
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: