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Flooring and Carpeting/Is new tile enough to stop a bathroom floor from leaking?


QUESTION: Hi. We have a bathroom with a floor in it that has at least one hole in it- when the bathroom floor is flooded water seeps through it and leaks into our basement below it.

We have adhesive tile on our bathroom floor- is putting new tile down enough to cover the hole and to stop the floor from leaking water into our basement below it?

Please let me know- thank you.

ANSWER: The short answer here is no. Whether you are putting down vinyl composition tile (VCT) or ceramic tile there are seams between the tiles. Even with grout between ceramic tiles water will still get through. Your best bet is to fix the hole. The last thing you would want is to put in a new floor and have to rip it up because the subfloor was still leaking.

---------- FOLLOW-UP ----------

QUESTION: Hi, thank you for replying. I asked another user here and he said:

"The only way to be sure water will no longer penetrate the floor is to take up the tile and put down a membrane of sorts to create a waterproof barrier, then retile the floor.  I suggest you contact a tile contractor to take care of this."

DO know know what he meant by "membrane"? Please let me know- thank you.

You would need a membrane if your subfloor is not of a waterproof type (such as plywood or OSB). A membrane is a separate barrier that would prevent water from getting into your subfloor and causing mold and damage.

Membranes can be anything from a liquid that is applied that forms a water proof barrier such as Hydro Ban
to a roll out membrane such as Ditra

I mention these because they are very popular. However, they are also used when there is also a concern about cracking in the tiles due to subfloor movement. If you had not had cracks in the past then you may not need to spend the extra money on such a system. In that case you may be able to use a product such as HardiBacker
This would be installed over your present subfloor. You would want to caulk edges and seams to be sure moisture does not seep through prior to retiling.

It is important to note that products such as Ditra and HardiBacker would raise your subfloor level 3/8-1/2 inch or so while a liquid such as Hydro Ban would only raise it about 1/32-1/16". A significant increase in the subfloor level can create a problem with opening and closing doors.

Also, please understand that even if your subfloor now is a waterproof type, such as HardiBacker, if it has a hole you will still have a leak. I am not sure how big your hole is but I would still recommend patching it even if you are covering it over as the above products still need adequate support from your subfloor.  
Please let me know if you have any further questions.

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R Adams


Certified Installer 1966-1976, Certified Carpet Cleaning Instructor 1976-1985, Certified Commercial and Residential Floor Inspector since 1985 is available to answer questions on problems with carpet or other flooring, and carpet cleaning. I can guide you as to whether you may have a valid claim against a manufacturer/installer/dealer/cleaning company.


Floor covering Installer 1966-1976 Carpet Cleaning Instructor 1976-1985 Floor Covering Inspector 1985- present

Floor Covering Inspector Training School; FCITS Floor Covering Inspection Technical Services; FITS Certified Claims Inspectors Association; CCIA

Hartford Courant

B.S. Chemistry 1971 A.S. Physical Science 1969 Armstrong Certified Installer 1972 3M Certified Carpet Cleaning Specialist 1976 FCITS Certified in Carpet and Hard Surface, Commercial and Residential

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