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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Aaron

Roger,

I’m remodeling my master bath, we tore everything out and down the to studs… The sheet-rock guys came through and they installed DensShield in the shower but seem to have taped all the corners and seams with regular drywall mud… I planned to coat the shower with Redgard but now I’m concerned.

Can I just coat everything with Redgard or do I have to tear it all out and use cement board?

Reply

Hank

Roger,

We are in the process of remodeling a tub bathroom. All the walls surrounding the tub were stripped down to the studs. So far the following has been done:
1. Insulation was applied to all walls (1 facing outside the house, 2 are not)
2. Stucco mesh paper was installed (chicken wire with black paper)
3. Coat of cement was applied (cement with sand, no grabble)

Next hardie-backer board will be installed. Porcelain tile will be the final phase. Question is, you’ve mentioned not doing a double insulation as it may trap moisture. Does the stucco-mesh with “black” paper count as a barrier?
My plan was to apply redguard (or equivalent) to the hardie-backer board before installing the tile.

Your input is much appreciated.
thank you,
Hank M.

Reply

Roger

Hi Hank,

Why?

What I mean is why the tar paper, wire and cement if hardi is going to be used? With the wire and mud between the hardi and tar paper you shouldn’t run into a problem with the redgard, it’ll be fine like that.

But why? :D

Reply

Michele

We were initially told to use greenboard around the shower – would Redgard be enough to waterproof the walls before tiling? The greenboard has been installed & now people are saying we should have used cement board, but we are hoping we don’t have to take down the greenboard after all the time and work that went into putting it up. Your input would be appreciated.
Thank you

Reply

Roger

Hi Michele,

No. Greenboard is not a sufficient substrate for either a shower or redgard. It needs to be removed and cement backer put in it’s place. Sorry, I know that isn’t what you wanted to hear. You can use kerdi over the greenboard if you want, but that’s it.

Reply

Luke

Hello,

Would painting RedGard over greenboard be sufficient for waterproofing the shower before tiling? Thanks!

Reply

Roger

Hi Luke,

No. Greenboard is not a sufficient substrate for either a shower or redgard. It needs to be removed and cement backer put in it’s place.

Reply

Dave

Roger,

I have a shower I am remodeling. One of the walls is the exterior wall, it has insulation and plastic over it. I was planning on using Hardie backer board with Redguard on the Shower wall. Will this be problem with the plastic on the exterior wall and Reguard on the other. I plan on putting Redguard in the whole shower.

Dave

Reply

Roger

Hi Dave,

I usually just cut a slit in the plastic the length of the stud bay. It doesn’t need to be removed or have huge parts of it cut out, you just need to not have the substrate totally sealed in with the two barriers. The slit allows vapor to dissipate when needed.

Reply

Kurt

Hello Tile-Elf,
Your PDF guide is excellent and a great go-to resource for newbies like me.
Here is my question: I removed a fiberglass surround and installed hardibacker in its place. Per James Hardie’s suggestions I left a 1/4″ gap between the bottom of the HB and the tub’s flange. The height of the HB is 72″ but the wife wants to run the tile all the way up to the ceiling (another 2 ft. at least). I don’t want to do this buy hey, what can you do?
So, I plan on using thinset morter on all the joints, including the transition to the existing drywall and then embedding fiberglass tape into the thinset.
I will use redgard to cover the HB. I don’t plan on applying it to the drywall (which is painted, by the way). Here are my questions:

1. Can I install tile above the 72″ on the existing drywall. It will be unlikely receive any direct water hits. Or, should I continue the HB all the way to the ceiling(please say no!)?
2. I am going to seal the 1/4″ gap at the bottom with silicone sealer. Is that OK?
3. There are some areas, particularly where the old drywall meets the HB, that are a little uneven, maybe by an 1/8″ in some places. I am concerned this will cause issues when placing the tile. Is it possible to do some feathering with the thinset? Or just play with the the thickness of thinset when I apply the tiles?

Thanks,

Kurt

Reply

Roger

Hi Kurt,

1. Yes, you can install tile up there directly to the drywall.
2. Yes, provided you install it, wait for it to cure, then go over it again to ensure you don’t have any open areas.
3. A combination of both would be best. If it’s only 1/8″ keep in mind that you should have somewhere around that amount of thinset behind your tile once it’s installed. It’s easy to adjust your tile over that amount of inconsistency with just the amount of thinset under your tile.

Reply

Mike

Not to beat a dead horse, but…. I put plastic on the existing floor and poured a cement mix on top sloping it to the drain. Kerdi was put on top of this all the way to the drain. My big mistake, other than not using the Kerdi drain was that I did not seal the Kerdi to the drain ring but rather tucked it in and placed the top ring of the conventional drain on top of that. I believe this led to a gap that trapped water and finally destroyed the silicon “seal” I put around the circumference.
Now, replacing with a Kerdi drain, would you put the drain on top of the existing Kerdi and seal with Kerdi Fix or Redgard or strip off the existing Kerdi, set the drain and return the existing Kerdi to the top of the drain assembly???
The whole floor in the bathroom is covered with Kerdi and the shower is a no hub, no enclosure made for ez access.

Reply

Roger

Hi Mike,

I would cut an 18″ square with the drain centered in it, install the drain, then place a 2′ square piece of kerdi over it to patch it.

Reply

Tracy

Roger-
I have a exterior window in my shower and is pretty deep which is nice because it also acts as a bench. The flashing tape adhered to the window framing extends in about 4-6.” I’m using topical moisture barrier and read that I shouldn’t add topical moisture barrier when there is a moisture barrier underneath the substrate. Does this count for flashing tape as well? Should I just add the topical barrier up to the point where the flashing starts?

Tracy

Reply

Roger

Hi Tracy,

No, it doesn’t apply in that application – paint it right up onto the flashing.

Reply

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