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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Joshua

Can you paint over redgard? like touching up the wall where your tile stops? and can you use drywall mud over redgard? :corn:

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Josh

Can you paint over redgard? like touching up the wall where your tile stops? and can you use drywall mud over redgard?

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Charlie Woods

I have gutted out a two piece tub and shower and have installed concrete board to replace it. I only have one bathroom and I am having to do this project after work so my question is…..Once the Red Guard is applied and dried, how much do I have to worry about getting the Red Guard wet (taking a bath) before the ceramic tile goes on.

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Roger

Hi Charlie,

Provided it’s cured you don’t have to worry about it at all. It will turn pink when wet, don’t panic, it’s normal. :D

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Ron

Roger
This site is great. Used it with my last project. Using it with this one as well.

I have a shower project and would like your advice. In my 2nd bathroom I have removed the existing tub/shower combo and replacing it with just a shower (3′ x 5′). The shower enclosure has three walls all cement boarded (durock) the fourth wall is a pony wall, curb and door (all glass). I had a mortar shower pan installed (a little wavy but sloped correctly. A couple of questions.
1. Waterproofing
Should I redguard the entire surface of the cement board including shower pan? I also read that you silicone corners. Do you suggest this?
2. Shower Pan
When tiling, can I just use more thinset under the tile in lower areas to smooth out the tile?

Thanks in advance

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Roger

Hi Ron,

1. Yes, provided you have a drain in the floor that can be used with a topical membrane and you DO NOT have a rubber membrane in there. If you do then no, do not use redgard on the floor. You can use it on the walls and paint it out onto the floor a couple inches, but you don’t want to go over a base with a membrane already in it.

2. Yes. Or you can simply skim-coat it with thinset first to even it out, then let that cure, then set your tile.

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Ron

Thanks Roger

Yes I do have the rubber membrane. So I won’t redguard on the floor.

Modified or unmodified thin-set for the skimcoat on the floor? Planning on using marble tile.

I was reading on your blog about vapor barrier (mold sandwich) and using redguard. One of my walls is an exterior wall and has vapor barrier. Should I remove the concrete boards already screwed in to access the vapor barrier to allow the vapor to dissipate? Right now the exterior wall has 6ml poly and cement board (joints not taped yet)

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Roger

If you only have one wall it’s not necessary. Doesn’t matter what type of thinset you use on the base, either will work just fine.

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Ron

Thanks Roger. You have been very helpful.

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Ron

I have one more question for you. Would using the Kerdi membrane on the cement board be a better option than RedGard for waterproofing the shower?

Thanks again

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Roger

I prefer kerdi because I can begin tiling right away. That said, they both work very well. Completely a personal choice.

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Lynn

We removed an old acrylic tub shower surround in our washroom. Then the sheetrock behind this. The house is almost forty years old. The vapour barrier and insulation behind smelled bad and removed that too. When we removed the vapour barrier and the insulation to the cold wall, we discovered the exterior wall badly water damaged. We wanted to install cement board and Redgard as the waterproofing membrane around our tub. Since it is an exterior wall, wouldn’t we need the vapour barrier and insulation behind the cement board???

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Roger

Hi Lynn,

Yes, but having in on one outside wall doesn’t create any problems.

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irene

we gutted our MBR shower which is back to back with the tub surround of another bathroom. we discovered that the area of sheetrock (yes sheetrock) surrounding the spout and two handles of that tub surround was well on its way to becoming mush. we cut out all the questionable area. the tub surround is fully tiled and the entire rest of the bathroom is tiled to 4′. the tile is 30 years old and we have tried unsuccessfully in the past to match it. at the moment repairing the hole is the only option. current plan is to cut a square of cement backer board to fit, seal it with redguard, and re-tile using the tiles we removed. given the circumstances, what is the best way to seal the cut edges of the existing sheetrock? red guard, silicone, something else?
thanks for a great site!!
irene

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Roger

Hi Irene,

Redgard is your best option. But the wall around the repair won’t last much longer either, once you waterproof that area that water will simply find somewhere else to go – the nearest un-waterproofed area of your drywall.

But you already knew that. :D

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irene

yup, we do. since our kids are grown and out of the house, once the mbr shower is completed, the other shower will rarely be used. so we can catch our breath a bit before plunging into another gut job.

thanks for the response and for all the info on your site. great info, great ideas.

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