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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Ed

Thank you Rodger. Have a great holiday season!!!

Reply

Ed

Hi Rodger. TY for this great info. Quick question …….I am going to redgard my cement board (no plastic behind). My plan is to lay the top deck mud, then hang the hardibacker (1/8-1/4 inch above final deck mud) then redgard. My question is how do I fill that small gap between the final deck and the board?
1) If I don’t fill it won’t there be a chance of water sneaking in there and going from the cement board to the bare wood studs?
2) if I am to fill it do I use 100% silicone and redgard on top of it and carry the redgard a few inches onto to pan floor?
Or……
3) Would it be easier (and smarter) to lay the board before the final top deck mud (do I leave a small gap above the pan liner in this case?) and bury the board in the final deck mud then cover with redgard to “avoid” the gap mentioned above to have a solid surface for the topical regard?

Does this all sound right? THANK YOU !

Reply

Roger

Hi Ed,

I normally embed the backer in the top mud deck, leaving about 1/4″ between the liner and the bottom of the backer. Or you can hang it above the top mud deck, it just hangs there, you don’t have to fill that gap with anything, gravity takes care of the water that ‘sneaks’ up behind there. Your liner should run up the wall about 12″, so the bottom foot of your wall is waterproofed behind the backer, water isn’t going to run up your liner.

Reply

James Spurr

Hello Roger, I am building a shower stall that is roughly 9 ft long and 4 ft wide. One end is steam and the other end is a car wash. The problem is that about 5-1/2 ft of one wall and 2 feet of another wall are extremely well insulated exterior stud walls with appx 1″ of spray foam behind a layer of tarpaper behind exterior stone, with fiberglass batt in the stud spaces. There will be some plumbing with fixtures in some of the exterior wall stud spaces. I am concerned about a moisture sandwich between the interior RedGard and the exterior foam insulation.

Can you offer some advice?

Thanks in advance, Jim

Reply

Roger

Hi James,

In a steam shower application (if part of your shower is a steam shower then the entire thing needs to be built as a steam shower) you are required to have a vapor barrier behind your backer with a topical waterproofing membrane on the walls. Exterior foam insulation is not going to cause a moisture sandwich, but you need a vapor barrier back there anyway, so moot point.

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