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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John

Instead of the mesh tape and redgard for seams, could I run a bead of silicone?

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Kristi

Hi,
I have a 3×5 shower whose base is deckboard covered with durarock then a rubber membrane was layed then a sloped mortar mud floor and adjustible drain. The membrane is sitting flat on the durarock covered deckboard with no slope I want to redguard the floor because I don’t want water to pool in the flat membrane below the mud pan. Did the guy who built the shower make a mistake by laying tha membrane flat beneath the mortared pan instead of laying it on top of the sloped mortar floor? If you use a membrane, is it placed on top of the sloped mortar bed and can it be redgard OR a rubber membrane? Please tell me how it can be fixed:( This shower is in a small stilt house 12 foot in the air and im afraid if i redguard the fllor with the rubber membrane at the base ill get that moisture lock you talk about with the walls. Thanks in advance.

Reply

Roger

Hi Kristi,

Yes, he did it incorrectly. A membrane is always to be placed over a preslope. The only proper fix is to remove and rebuild the floor with either a proper preslope or build it with a single slope with redgard on top of it. Redgarding over what is there now may cause issues down the line.

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Vince

Hi, Roger. I am getting a shower installed with Durock cement backer. My drywall contractor taped and joined the seams, including the corners where drywall meets Durock. Now there is some setting-type joint compound on parts of the Durock that I plan to tile over (extending 2-4″ from the edge). I plan to use Redgard before tiling. Do I need to scrape the joint compound off? Or, can I just prime over the joint compound before putting on Redgard?

Reply

Roger

Hi Vince,

As long as it’s flat you can prime over it.

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Bill

I have a tub surround and would like to tile from the top of the tub surround to the ceiling. Do I need to rip out the drywall above the surround and replaced with cement backer board? Or can I apply redgard over the drywall then tile?

Thank you,
Bill

Reply

Roger

Hi Bill,

As long as it’s over 2″ above the shower head you can redgard it and tile it. You actually don’t need waterproofing there (2″ above), but it certainly doesn’t hurt.

Reply

Job

Hello Roger

bought your ebooks on waterproofing and tips for tiling showers and found them as helpful as your excellent blog posts. I want to ask a couple of questions to be sure I’m clear on how to handle my current shower project:

1) I can’t find clear instructions on how to handle sealing the joint between the top of my cement backer (wonderboard) and the ceiling (green sheetrock) — my best guess from reading your info would be to use silicone for this gap, but do I also tape it with the fiber tape first? I’ll stop guessing and wait to hear your answer :-)

2) As a novice DIYer, I was following Lowe’s guidance on waterproofing my shower which indicated to do a vapor barrier AND a waterproof barrier like redguard. I was planning on using redguard after filling the seams with thinset which I am ready to do tomorrow in fact — however–

I do have a vapor barrier behind my cement backerboard. I like to be as thorough as possible for waterproofing so could it make sense to redguard the seams, corners and ceiling joint (maybe not ceiling but I would have before reading this blog post) but do not Redguard the face of the boards? Would this allow extra waterproof protection while still allowing room for evaporation, or am I better off not using redguard at all?

Looking forward to your reply and really glad I found your site!

Job

Reply

Victor perez

hey, thanks again for your help.
I have my walls up (durock),
first layer of mud bed has been laid,
I wanted to ask
if I am doing a Redguard membrane do I still need a shower liner above the first layer in between the second layer of the mud bed?
if so once I install the liner and lay my second layer, do I then Redguard the top of the mud-bed, then install my tile?

Reply

Roger

Hi Victor,

No, you do not. You don’t even need a second layer, you only need one slope for a topically waterproofed base.

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Valerie

My contractor is proposing to install a vapor barrier in a shower stall behind the hardee/durock board – it is a brown paper material on one side and the other side looks like foil. Is it still possible to use redguard or the mapei aqua defense on top of the cement board, or is there the possibility for moisture to become trapped as you describe above with the use of plastic. Please advise. Thanks.

Reply

Roger

Hi Valerie,

It is very possible to trap moisture in there with a topical membrane over the top. I have no idea what that product may be, but it likely isn’t a product made for a shower barrier.

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Bob Markus

Have several rental properties: Have a tub surround where I have to replace the wall down to the studs. I have left over 3/4 ” AdvanTech flooring. Can I use this to replace the wall board around the tub? I will be using Maax polystyrene glue-on panels for the surround. Will this cause any type of water moisture/ mold problem? Thanks for your help. Bob

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Javier Martinez

I have a question guys. Can you tile directly over the redguard (shower pan) flooring? I dont know how I found this site so please email me thanks in advance! JMartinez

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Jim

Excellent and informative site, thanks.

My question is in regard to using Redgard on Hardibacker, I have read about many people having issues with proper adhesion due to the hardie being so dry. The install instructions for Redgard seem to indicate that a primer coat (1 part RG to 4 parts water) is recommended with fiber cement boards.
Have you had experience at all with this issue? The primer coat is not mentioned in the instructions for Laticrete’s Hydro Ban, and I have heard the adhesion is better. What liquid waterproofing membrane would you recommend specifically for use with Hardiebacker? Thanks for your time.

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Bill

I have removed a tub surround and want to put tile in it’s place. Some of the top coating on the drywall came off where the surround was glued to it.
Do you know if that can be repaired in any way or do I have to replace it before using the Regard. It is sturdy and in good shape otherwise. Thanks for your help.

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Roger

Hi Bill,

You can not use redgard over drywall. The drywall needs to be replaced with cement backerboard.

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Salman

I have taken out tiles, grout, boards underneath the shower bench/seat (this area is about 3 ft x 1.5 ft, not that big), found that builder did not use Cement board, rather following construction method was employed.

Tile + Thinset + Redgard + Green mositure control board + drywall board + studs

Now, i want to do this thing in a right way … since the builder used 2 board each of them 0.5 ” , can I replace the old construction with the following ?

Tile + Thinset + Redgard + Hardie board 0.42″ + Pressure Treated Plywood +studs

Reason for having the same kind thickness for the whole thing is that I cant move the aluminum shower frame.

Question 1 : Can I use Exterior grade plywood in wall over stud, any recommendation on plywood?

Question 2 : Also if Plywood is used do I need to apply a fine layer of thinset mortar on wall also just like they do it on floor ? why they apply thinset between plywood and hardie board in floor ?

Thanks and appreciate your feedback in advance !

Reply

Roger

Hi Salman,

Just shim out your studs with strips of any type of wood to get your backer flush with where you need it. Since you are using redgard over it the type of ply doesn’t really matter. No need to use an entire sheet over the studs, just rip down strips as wide as the studs as shims.

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Tom

Roger, got your book, one thing not clear to me, at the change of plane where the side walls meet the back wall do I:

1.) Use silicone caulk wait a day then redgard over
2.) Use silicone caulk wait a day then embed mesh fabric in the redgard
3.) Tape and thinset wait a day then redgard over
4.) Caulk, wait, tape and thinset, wait, then mesh fabric in the redgard
5.) Something else?

Reply

Ryan

Roger,

I have the exact same question – thank you!

Reply

Roger

Hi Tom,

#3 – tape and thinset, wait a day, then redgard.

Reply

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