Tile is NOT Waterproof

by Roger

A common misconception about tile and grout is that they are waterproof. Once you install tile in your shower you have a big waterproof box that will last forever. Ummm, no.

Tile and stone (as well as grout) will actually retain water. How much water it retains is directly related to the density of the tile. For instance, porcelain tile is much more dense than travertine. This means that travertine will retain more moisture and allow more water to seep through¬† to your substrate. If you happen to have travertine in your shower – don’t panic. As long as it was installed properly it will be fine.

So how do they figure this out?

When a specific type or brand of tile or stone is manufactured for production, the company will determine its density. There are four different categories into which each tile may be placed.

This is determined by weighing the particular tile, submerging it in water for a period of time, then weighing it again. The difference in the two weights determines the density or absorption of that product. Basically how much water it holds. It will then be placed into one of the four categories.

  • Non-vitreous: These are tiles that absorb 7% or more of its body weight. These are for indoor use only, normally on vertical surfaces such as backsplashes and wainscots.
  • Semi-vitreous: These absorb between 3% and 7%. These are also for indoor use only.
  • Vitreous: Absorb between 0.5% and 3%. These tiles may be used for interior and exterior applications.
  • Impervious: These are the most dense (porcelain) and absorb between 0.001% and 0.5% of their weight in water. They are suitable for all applications.


Depending upon where you intend to install the tile you may need to consider this. In most cases it’s not an issue. Only in the most extreme or unusual circumstance will you need to take into account the category of your particular tile. A tiled patio in Alaska, for instance. If you have a tile that absorbs a considerable amount of moisture and it freezes, well, you’re gettin’ a new patio.

The biggest factor to consider is the amount of water to which the tile will be exposed. (Along with the possibility of freezing, of course.)¬† For anything up to and including a regular shower, it isn’t necessarily an issue. These applications, using proper methods, should be at least water resistant before a box of tile is even opened.

Why is this an issue?

With any tile application, the durability of the tile will be only as good as what is beneath the tile! Let me say type that again – that again.

If you have a wall in your shower with just plain drywall and you stick your tile to it, it may look good for about a year. It may look good for much longer. But, if moisture gets behind the tile (and it will) through the drywall, to the framing studs, well, you’re screwed.

Your framing studs are (most likely) just simple 2 X 4’s. If even a minute amount of moisture from your shower reaches it all hell’s gonna break loose. Common studs will do what we call “wick” moisture. It is aptly named because it acts just like a candle wick (tile guys are simple folk).If you place one end of a candle wick in water the other end will be soaked in short order. Wooden studs do the same thing.

Think of it as a water highway. The water will simply continue along that same path until it finds something else to soak into. That something else is more wood. When wood gets wet it . . . wait for it . . . swells. Normally that swell has only one place it’s going – right against the drywall and into the back of your tile. Tile’s will crack, grout will crack, your patience will crack, and the end of the world will be right around the corner. You get the idea.

This is not (normally) a subject that needs to be considered when installing tile on your floor. A shower (or other wet area) is unique in that it is subjected to a great amount of water on a regular basis. Unless your kitchen is a swimming pool you really don’t need to be that concerned about it.

Just understand that tile and grout are not waterproof so care needs to be taken to eliminate as much moisture from the surfaces as is realistic in any given application. You know – don’t make your kitchen floor a swimming pool.

Previous post:

Next post:

Riveter

We have lost our second shower pan, so now we ancients are attempting to rehab our bathroom. We bought a cast iron shower pan( ( ouch!) and have begun demo. I started reading about the shower tile I bought for the surround and I am getting worried. It is a ceramic, mosaic, gloss tile (thought I bought porcelain) and it is non- vitreous because it indicates a 7% or greater absorption rate. Do I need to take it back? We are planning on using Hardiebacker 1/2 inch for the surround support and giving it a redgard prime then 3 coats.Have we totally screwed up getting this smaller, mosaic subway tile with the 7% or more absorption? Thank you. You are the biggest blessing we have found in all of this.

Reply

Tina

Hi Roger,
We recently bought a house an both of our upstairs bathrooms are now leaking. We have completely gutted the first bathroom to the studs and are starting repair and remodel DIY. We are going to use porcelain tiles on the bathtub surround and the floor. What is the best way to waterproof? I have read to of course waterproof the surround as well as the entire floor. I have also read that it is not necessary to waterproof under the tub, but we would like to. The leak we had was in the valve mechanism so there was lots of rot on the floor and we have small children who often create large puddles during bathtub. We are considering using Schluter Ditra under the tiles, should we also use it under the tub? We liked the Kerti system for the surround but didn’t like the price, any suggestions that are more budget-friendly?

Reply

Sharon

I am screwed. I have water leaking down to my basement and staining the walls and pooling around the air conditioning. The water has gotten behind the tile and the toilet. It leaks when you flush and whenever you use the shower. The plumber I hired showed me that some of the tiles are cracked and that the tiles next to the toilet are uneven. I don’t know what to do about this. I am guessing the water has probably gotten to the wood inside of the wall I am guessing. I have the insurance company coming out to look at this. I don’t have thousands of dollars to fix this.

Reply

Sharon

I didn’t tell you that I live in Virginia.

Reply

Roger

Hi Sharon,

If water has gotten into the substrates, which it sounds like it has, then it needs to be replaced. The leaks are what caused it, but the cracked tiles did not cause leaks, if that’s what you’re getting at. You may have an improperly built shower, but you have given me limited information with no real questions. :D What can I do for you.

Reply

Kristin

Hi Roger,

I don’t know if I’m leaving my questions in the right spot or not – but here they are.

We recently bought a house and there are a couple tile issues. The bathroom floor has large tiles. In one area they are loose and in various areas some or most of the grout is gone. Can I do a grout repair or do I need so remove some tiles first go from there. Perhaps you have another post I missed on this one.

The other issue is the shower floor which is a stone tile floor. We’ve been in the house a couple months and I recently noticed cracks in the grout lines running from one of the corners to the drain, in the center. Can I remove the grout and repair?

help! :eek:

Thanks,
Kristin

Reply

Roger

Hi Kristin,

You really should pull a couple tiles to see why the grout is cracking, both on the floor and the shower. This will help: Why is my grout cracking

Reply

Kristin

Ok, I’ll give it a try. Thanks for the link to the other page.

Reply

Marc

I bought some glazed ceramic tile for a shower area. It’s rated PEI =3 and labeled non-vitreous. Can I still use this type of tile in a shower area above a tub if properly installed?

Reply

Roger

Hi Marc,

Yes.

Reply

essen

thanks for your beutiful articles and helpful ideas

Reply

Lorenzo

Hi…great stuff you got. I’m having a shower hot mopped. Can you tell me where the bottom edge of the backer should be in relation to the horizontal plane of the pan?

I plan to RedGard the backer. Should I also RedGard the under edge of the backer, or not?

Please let me know before my head explodes.

Thanks,
Lorenzo

Reply

Roger

Hi Lorenzo,

It should be about 1/4″ off the deck. You can redgard the bottom if you want, no real reason to, though.

Reply

am10

Hi, I am shopping for floor tile for a bathroom remodel. I have found a beautiful tile described as “grade 1, first-quality ceramic tile for floor and wall use. P.E.I. Rating IV has high resistance to abrasion and is suitable for heavy-duty residential and commercial kitchens, hotels, exhibition and sales rooms with some dirt conditions. Semi-Vitreous flooring.”

Is this the appropriate grade and if so, can I use semi-vitreous tile on the bathroom floor? :corn:

Reply

Roger

Hi Kimberly,

That is rated more than enough for your bathroom. Any grade 3 or higher (lower number) is sufficient for use in residential bathrooms. Most ceramic and porcelain is semi-vitreous. So yes, you can use it on your floor.

Reply

am10

Thanks Roger!
:-D

Reply

John Covell

Roger-We live near Syracuse, NY with lots of snow. We have a two car garage with a basement beneath. Water from snow melt off cars leaks down thru the concrete garage floor into the basement. The prior steel plates rusted and l replaced the garage floor last year ($30K including french drains around the garage). We have hired several “wet basement” contractors thru the years to apply their various compounds and this has not worked. I have about $45k in this garage floor over 20 years. I tried rubber mats last year and that did not work. Is tiling the floor an option that will keep out water. This basement is our only storage area. The previous owner hid this problem with a hung ceiling in the basement. Thanks! John PS: We may reluctantly move from the frustration of dealing with this problem over 20 years.

Reply

Roger

Hi John,

Tiling it is an option. If properly waterproofed beneath the tile and up the walls a couple of inches then the water should drain out the front of the garage as intended. I’m assuming it was intended, anyway, your floor should be sloped down the the garage door.

A better option, though, might be an epoxy garage floor coating. If done on the floor and up the walls a few inches that should waterproof it as well. The perimeter would need to be prepped to be able to tie the epoxy in one layer from the floor up the walls, but it should work just fine. Have you looked into that?

Reply

Tabitha

Hey there!

So I need to replace flooring in my basement. We recently had a flood and my wood flooring was basically… killed. I was thinking tile would be a better option in case we had the problem again but know basically nothing about DIY home repairs. My reasoning is that they use tile for in-ground swimming pools so why not the basement. What say you? Am I going to end up with another hot mess?

Thanks!

Reply

Roger

Hi Tabitha,

If properly installed a tile floor is the ideal solution for your basement.

Reply

Jessica

Ok, I have another question, on the traditional route. My shower is not a “box”, it is like an extension of the tub with glass surround. So, if my waterproof membrane goes under the cement backerboared, & the cement board absorbs water, wouldn’t it just transfer moisture along the wall? So I would have to waterproof my shower walls, walls around my tub, & tub deck?

Wouldn’t it make more sense to use a topical approach to waterproof the areas that really get wet?

I could be overthinking this…

Reply

Roger

Hi Jessica,

If gravity did not exist yes, it would travel sideways along the walls. :D However, since it does, all the water gets pulled down. If everything is properly sloped then it will end up in the drain. Topical membranes, however, are always a more efficient option.

Reply

Jessica

Again, thank you wizard of tiling! I have learned a lot from your site. Too bad you aren’t where I live :wink:

Reply

Lory

Thank you. I have barely started on the Floor Elf site but am grateful to have found it for the floor knowledge here and for the warped sense of humor. I can certainly benefit from both! :rockon:

Reply

Roger

Hi Lory,

You’re very welcome! And welcome. :D

Reply

Jessica

Hello Tile Genius,
I have a huge mess on my hands. We built our home 5 years ago & the General Contractor told us to go pick out tile. We picked out something pretty & had a a tile contractor install it. Now the tub deck, which goes though to the shower, has expanded half an inch, causing major cracking & I’m worried about mold damage. I don’t believe anything was waterproofed at all.
I want to redo this mess myself to ensure it is done right, but I a total novice. Do you have advice or step by step article for showers & tub combos. I have been quoted $15k & am pretty much screwed because I can’t afford that.

Thank you so, so much for this article, it has opened my eyes. :dance:

Reply

Roger

Hi Jessica,

You’re absolutely correct, nothing was waterproofed. That’s why it’s swelling. I have all sorts of stuff – you can begin with my free download describing the pros and cons of different methods of waterproofing and what’s available here: Waterproof shower manual Read through that and go from there, I’m always around to answer questions.

Reply

Jessica

Thank you so much for your reply. I’m also curious about the glass shower surround. I’m worried the pressure could crack the glass, not sure if that is so.
You might not know on this, but how do I convince my husband this has to be ripped out, lol. :lol1:

Reply

Roger

It could. It depends on how much it’s swelling. It will continue to swell if the shower is used. Just tell him he can pay for a shower now, or pay to have that half of the house framing rebuild – and a shower in a couple of years. :D

Reply

christie

I have a question about what kind of tile I should put on as a bathtub surround. I was wondering if you think this would be suitable…..

Grade 1, ceramic tile for floor and wall use
13.5 in. length x 13.5 in. wide x 1/4 in. thick
Glazed smooth finish with a medium sheen and random variation in tone
P.E.I. Rating IV has high resistance to abrasion and is suitable for heavy-duty residential and commercial floor installations such as entrances, commercial kitchens, hotels, exhibition and sales rooms with some dirt conditions
Non-Vitreous tile has water absorption of more than 7% for indoor use
C.O.F. greater than .50 is recommended for standard residential applications and is marginally skid resistant. Indoor use
Not frost resistant; suitable for exterior walls in non-freezing climates only
Suitable for residential use

do you think this would work in a wet environment?……I was also going to have it installed as flooring but I am worried that it will be too thin and crack. ( I’ve read some bad reviews on other styles of the same brand/type and I’m nervous that in trying to save a dime I will shoot myself in the foot!…..my contractor is very good and I trust him. I just want to make sure I am leaving him with the right stuff, as we will be out of town for the renovation. any advice?

Reply

Roger

Hi Christie,

Grade 1 ceramic tile should only be used on walls. If you only want to do the tub surround with that (as you’ve mentioned) it will be just fine. Do NOT use it on the floor. Get at least a grade 2 for the floor. Provided your shower surround is properly waterproofed that tile will be just fine.

Reply

Sheila

Hi,
I have a recently installed travertine tile shower. They hot mopped it, used hardy backer, etc. I “think” it was done correctly. However, I just noticed a crack on one wall tile that I know was not there originally. Can travertine tiles settle? Could this cause the crack? And is there a way to “fix” a cracked tile without ripping it all out? (There is a stationary glass panel attached to this particular tile.)
Thanks!!

Reply

Roger

Hi Sheila,

No, tile will not settle. It could have been a weak striation through the tile which let go and cracked as the thinset shrunk when it cured (it will shrink a little as it cures). You should be able to just remove that tile and replace it. If there is not a crack through the backer it’s likely just a flaw in the tile itself.

Reply

Sheila

Thank you!

Reply

Mike

Installed a steam shower. It was installed as follows. Framed with 2×4’s, then 40mil Oatey membrane over every sq. inch, put on with gal. nails and all of the seams glued with Oatey glue, mud pan, durarock over the membrane on walls and ceiling, installed with screws, seams on Durarock caulked with sil., then porcelain tile, and epoxy grout. I understand now that this was not the proper way to install a steam shower that moisture will get through the screws to the 2×4’s. One forum told me to tear it out and start over that as a shower it will last forever but as a steam room anywhere from 2-30 years or more is what I am hearing. I do have access to 2 of the three walls where I can keep an eye on things. Also, if you think I should use it and monitor what is going on how long should I let everything cure before use? I would appreciate your advice. Thanks

Reply

Roger

Hi Mike,

I wouldn’t even give it 2 years. Steam infuses moisture into the substrate. durarock is not waterproof, let alone steam. It will get back there in short order. I honestly wouldn’t use it as a steam shower at all. If you do I give it MAYBE six months of regular use before you develop problems.

Reply

James Newport

I am not a great diy person. But recently made a shower cubicle. I sand and cemented the walls and then drilled 6mm wbp plywood to the walls and tiled directly onto that. I’m now having serious doubts. Will it be ok or not worth the risk??

Reply

Roger

Hi James,

That plywood ABSOLUTELY needs to be removed. Once water hits it you will have one hell of a mess on your hands.

Reply

Tish

I am in the final stages of building a house, I noticed the “step/seat” was dry wall framed (white part exposed) and not sealed or waterproofed before they laid tile on it. I am pretty sure this will cause problems later. Should tell them to take the tile out and water proof the step?

Reply

Roger

Hi Tish,

Yes, absolutely! Drywall will soak water in like a sponge and redirect it back into the wall framing. You’ll begin to have problems with that within six months.

Reply

Graham

We just bought our first house (rambler from ’57) and remodeled the basement. We laid new porcelain tile on top of old VAT (asbestos tile) with mortar. We haven’t caulked it yet (hadn’t had time). But then the basement flooded (1” standing water). Will the tiles be ok if we get the water out?

Also, the wood framing is soaked on the bottom, does that mean we need to take it all out (there is drywall in the basement).

Thanks!

Reply

Roger

Hi Graham,

Under a normal installation your tile would not be affected at all. However, over the vat the integrity of the installation will depend on the integrity of the installation of the vat. It may be fine, it may not. Absolutely no way for me to tell, you’ll need to check it out after you get it dried out. Same with the walls, I’m sure the drywall will need to be removed, dry out the framing, then new drywall. I have no idea to what extent the damage may be – I can’t see it from here. :D

Reply

Phill

Our young sons are continually splashing water out of the laundry tub we use as a bath onto the floor. I am noticing concrete grout is now cracking between tiles , do we need to lift them or just allow to dry and regroup?

Reply

Roger

Hi Phill,

I assume the tile is installed directly onto a wooden substrate if water getting on it is causing cracking. That normally means water is seeping down into the substrate and the substrate swells with water exposure. That would mean wood. If that’s the case then they should be removed and a proper substrate put in place beneath them.

Reply

Toni

We opened part of a wall in a closet that had moisture seeping out from the baseboard, the other side is a shower. There wasn’t a leak just a loose neck from the shower head, it got tightened. There wasn’t any more moisture seeping from the bottom but noticed condensation inside the plastic lining for the bottom of the shower. The drywall the lining touches is very damp. Could that be just water seeping through the tile and grout? Not sure what kind of tile it was remodeled before we moved in.

Reply

Roger

Hi Toni,

The condensation is normal where there was water leaking before. Water will get through the tile and grout but should be contained on the shower side of all the membranes. If it were a leak it would be in one specific area and there would be more than just a thin layer of condensation.

Reply

norm

I pulled tile from around a bathtub, that was 40 years old. I was SHOCKED to find plywood behind the tile. And the plywood was as good as new. The guy who did it, was an old italian mason whom knew things I do not know. It does make me rethink durarock.

Reply

Roger

Hi Norm,

Don’t rethink the durock unless you’re using solvent-based mastic (which has since been outlawed) which infuses oils into the plywood causing it to shed water rather than soaking it in.

Reply

Leave a Comment

;) :wtf: :wink: :whistle: :twisted: :suspect: :shades: :roll: :rockon: :oops: :lol: :lol2: :lol1: :idea: :guedo: :evilb: :evil: :eek: :dance: :cry: :corn: :cool: :censored: :bonk: :arrow: :D :?: :-| :-o :-P :-D :-? :) :( :!: 8)