Installing Redgard on Shower Walls for Tile

by Roger

Elastomeric or liquid waterproofing membranes are one of the most convenient methods of waterproofing shower walls before installing tile. These membranes consist of products such as Custom Building Products’ Redgard and Laticrete’s Hydrobarrier and Hydroban and Mapei’s Aquadefense. I will refer to all the membranes as Redgard for the purposes of this post, but they all work nearly the same way.

These materials can be installed with a regular paint brush, paint roller, trowel, or even sprayed on. They are applied to your shower walls then tile is installed directly onto it. When I use these products I always use a cement-based backerboard as the wall substrate without a plastic vapor barrier.

redgardIt is imperative that you do not install plastic behind your walls since this would create two waterproof membranes with your substrate between them. Having two barriers this close together leaves open the chance of trapping moisture between them with no way for it to evaporate. This may lead to mold.You must also tape the backerboard seams with fiberglass mesh drywall tape.

The easiest way I have found to install Redgard is, after the walls are prepped properly, start with a paint brush and thoroughly coat all the corners and angles. The membranes are more the consistancy of pudding than paint so don’t be afraid to scoop it out to spread it. You should be used to it after a few minutes.

After all the corners are coated I use a paint roller and pan to cover the walls. Redgard is bright pink – I mean pepto-bismol pink, it almost glows in the dark. This is useful in that when it is dry it turns dark red. The other membranes are similar. Laticrete’s Hydroban, for instance, goes on light green and dries forest green.

Just thoroughly coat the entire inside of your shower until the whole thing is bright pink – enough so it can be seen from space. That’s it – go have an adult beverage until it dries. You must then do a whole second coat the same way. Make sure the first coat has fully changed color before applying the second coat. If you are using a roller Custom (the company that makes redgard) recommends that you roll on the first coat horizontally and the second coat vertically to ensure full coverage. (Thanks for that Davis)

Most of the product specifications for these materials state two coats to be sufficient, and it probably is. I normally use three coats. I’m weird like that. Unless you have a steam shower or something similar, two coats would probably be enough. It’s up to you.

These products shrink a bit as they dry so you must make sure that it has not shrunk enough to create holes or voids in places such as corners and seams. You need a full coating for the product to be effective. When you are finished you should let the walls completely dry for a day before tiling.

Your tile can then be installed directly onto your walls over the membrane with a proper thinset mortar. When these products set they will create a rubber-like coating on your walls that is waterproof. When used on shower walls it is a (relatively) quick, effective water barrier for your installation.

These products can also be used as waterproofing on your shower pans in leiu of a regular pan membrane. Make sure your specific product includes specifications for this application if you choose to do that. Check the respective website for your particular product. I do know you can do this with Redgard, Aquadefense, and Hydroban.

I also use these products for main or additional waterproofing on things like shower niches and concrete wall in basements, places where it is difficult to have a plastic vapor membrane behind the backerboards. Basically any place that does not have waterproofing between the tile and shower framing. I always have Redgard with me. The versatility of these products make them a integral part of my shower waterproofing toolbox.

The only drawback for these products, if you choose to look at it that way, would be the price. They are a bit expensive. You may be able to get better prices by ordering online but make sure you take shipping costs into consideration. You can get a gallon of Redgard online for about $45.00 plus shipping. That should be enough to do a regular tub surround. That is a five foot back wall with two 3 foot side walls. For larger showers you can also get a 3.5 gallon bucket.

Make sure to check the website for your product, they have a load of information for them. As always, if you have any questions feel free to leave a comment for me.

RedGard website

Laticrete website

Need More Information?

I now have manuals describing the complete process for you from bare wall studs all the way up to a completely waterproof shower substrate for your tile. If you are tiling your floor and walls and using a liquid membrane you can find that one here: Liquid Topical Waterproofing Membranes for Floors and Walls.

If you are just tiling around your tub or pre-formed shower base you can find that manual here: Liquid Topical Waterproofing Membranes for Shower Walls.

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Hey – love your site. Have a few questions.
Customer wants clear glass tile (1″x3″) on the shower walls – this poses some questions and concerns.
1) I see that most glass tile needs modified thinset (I am still waiting for a reply from this specific tile mfgr for installation specs, but I am assuming they will recommend modified). This rules out my favorite – Kerdi (right?). Can you suggest a topical membrane that I can use in conjunction with glass/modified thinset?
2) Since the glass is clear, is using a white thinset enough to ensure that the color membrane won’t show through? Do they make a white topical membrane?
3) Do you have a manual about cutting this stuff. The last glass tile I used was on a back-splash and the typical wet-saw I used cracked the tile, made lovely skin cutting glass shards, and the cut edges were rigid.

Any help is appreciated.




Hi Kane,

1. You can use any of the liquid membranes. Correct, you should not use kerdi.

2. They do not make a white membrane. I will normally skim-coat the membrane first, let that cure, then install the glass.

3. I do not. I use my Sigma to cut most glass tile, not a wet saw. If you use a wet saw you should get a glass-specific blade for it.

As an aside: Clear glass in a shower is not really a good choice. Since water WILL get behind your tile you will be able to see it. ALL thinsets change shades when wet. The wetter parts of the wall will show through and there will be a ‘line’ of water similar to looking at water trapped between two panes of glass. It will dry out, it’s normal, but it will be seen. I would absolutely ensure your client knows that before moving forward, it will also cover your ass when she calls and says ‘my shower wall is turning different colors (shades)’.



Dude, your awesome. Very educated/experienced.
I showed the customer your reply about the clear glass tile, and considering the area we are in, where the water is less than clean, it makes sense to avoid a glass tile where the thinset will be visible and thus eventually stained – they are appreciative (as am I) of the information and are reconsidering the tile selection. I am checking to see if the original choice is actually clear or if there is a backing of sorts to prevent this issue.

Some more questions if you don’t mind….
1) Hydro Ban vs. Hydro Barrier vs Redguard?
2) Durock vs. Hardibacker. I prefer Hardibacker due to it’s moisture resistance, but I ran across a website suggesting that it was inferior and didn’t work well with liquid membrane?
3) Where the liquid membrane meets the tub surround – will the membrane stick to the fiberglass? I would think that there should be a 1/8″ to 1/4″ overlap between the backerboard and the fiberglass flange.
4) Transitions to the sheetrock. Is it Ok to have the membrane extend past where the tile will go? Will spackle/paint stick to the membrane – or should we stop just shy of the tile edge?
5) I have browsed your library and have found lots of publications I would like to purchase, however it seems that they are very specific. Do you have just one big book or bundle that covers just about everything? If so, please direct me to it/them.

Thanks again


Jim Spurr

Just a couple of notes from the peanut gallery – – I did my first glass tile work about a month ago. The key was buying a blade specifically made for glass, and cutting slowly. I found that cutting in 2 passes was best to avoid chipping: the first pass is shallow and slow to score the visible surface, and then turn it over to complete the cut through from the back side. I then used a file to graze the cut edges to ‘soften’ the sharpness.

As far as seeing through the glass to the mortar, membrane, etc – – [note: I have only done this once, and did not research far and wide, so my experience is very limited] All the glass tile I found actually had an opaque film on the back side, which gave it its color – – in fact, although the glass looks colored (like stained glass), it is actually just clear glass with the colored film on the back side. “Clear” looking glass tile just has a white film on the back side. If your client is actually looking at glass tile that you can see through like a window, perhaps you could steer them to the kind with the film on the back. I see no useful benefit to see-through tile … they will only see the setting materials … (why?!)


Joe F

Hi Roger, when using Redguard on backer board, regarding the joints (both within a plane and at the corners, do you start with a gap between boards, then tape it with standard drywall fiberglass mesh tape (not the alkali-resistant kind), then apply the Redguard? That is, you don’t first have to tape and bed the joints with thinset, right?


Bob R.

Hi Joe F, I’ve been reading Roger’s blogs and E-Books for about 2 years now and I think Roger will back me up on this correction to your proposed materials and methods you are asking advice on above, so here goes.
Hopefully you haven’t taped and mudded yet as you really do need to use the alkali-resistant mesh joint tape, NOT the standard fiberglass mesh tape, as the regular stuff doesn’t hold up very long when the modified-thinset reacts on it (too acidic I think).
I have just been taping over the 1/8 gapped durock or Hardibacker substrate boards flat joints and then mudding over that with Modified Thinset, while just pressing hard as I mud and that will push the thinset through the mesh to fill the 1/8′ gap, without having to first pre-mud the joints before applying the mesh.
Also, you don’t want any thinset in the change of plane (corner) joints. Fill those flush with 100% silicone (this will keep the thinset out), then let that set up a bit, and then use the alkali-resistant tape folded in these corners with modified thinset feathered out over the mesh tape. Then let all that set for 12 hrs or so and go on with your liquid waterproofing. You may?? also need to use a wider (5″) reinforcing mesh in your corners along with the liquid waterproofing application depending on what the manufacturer wants. It will take 2-3 coats of the liquid waterproofing to achieve the proper consistent thickness, I think Roger says the thickness is about the thickness of a credit card or a bit more, and will achieve that in 2-3 layers using the manufactures recommended drying time between coats.
What do you say Roger, did I state it correctly (but probably using 5 times the space you could write it in, huh?)



Hi Bob,

You’re hired!

Well stated, thank you. You can, however, also use unmodified thinset, not that you would when using redgard, but I thought I’d throw that out there because SOMEONE is going to ask. :D



Hi Joe,

You do have to tape and bed the tape first, let that cure, then paint your redgard over them. You still need to tie the boards to one another, taping and mudding them first is how that’s accomplished.


Jim Spurr

Hi Roger, when figuring estimated total thickness of a finished wall, what is the nominal thickness of the thinset? (context: 6″x24″ wall tile, 3/8″ thick on Kerdi board) Thanks again, Jim Spurr



Hi Jim,

It will be half the size of your trowel notch. If you are using a 3/8″ trowel your thinset bed will be 3/16″.


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