RedGard Waterproof Membrane

The next step after the thinset is dried on the walls of the shower will be the application of RedGard waterproofing membrane. This waterproof coating will be the final protection from any water that could seep through the grout of the tile. Since sealing tile grout can only do so much, waterproofing your backer board is essential.

The application of RedGard is very simple as long as you keep a couple things in mind. Besides the toxic smell of something that resembles an old memory of bleaching hair, it’s the application process that becomes the challenge of whether or not this will go smoothly and quickly. The consistency of the RedGard is like pudding and will be like applying putting to your walls. being said, you can imaging how messy this process can be if you are not careful with the amount that you apply on the wall at one time. The trick I found that worked well is to use a 4 or 5 inch paint brush and paint the RedGard on the walls then follow up with a 3 or 4 inch 3/8 nap roller to even out the coat.

Once the RedGard is applied onto all of the walls, it dries pretty quickly so you will need to balance between being as neat as possible and moving quick enough to apply before it dries. Once you have completed all of the surfaces of the backer board, wait about an 2 hours and apply a second coat the same way.

RedGard does color change which makes it really easy to tell when it’s dried. When you apply it onto a wall you will see that it is extremely pink in color. Once it dries is turns dark red (like the image below).

Remember to wear cloves, eye protection and a long sleeve shirt. Once this stuff dries on your skin, it will take days to get off without using chemicals. Also, mask away any surfaces that are in your target zone but won’t be getting the RedGard treatment. I got a little on the window frame and it’s possible that it may be on there for life.

Here are some of the images from today, feel free to ask any questions about the process as it’s was fun yet challenging.

RedGard Waterproof Membrane

RedGard Application

{ 9 comments… add one }
  • Harry February 22, 2014, 12:40 PM

    How long before I can seal with Redgard over newly poured 4:1 Mapei mud bed mix before tile is done? I see it says wait 28 days over new concrete but I am not sure about Mud Bed Mix mortar.


    • Jason Esposito February 22, 2014, 2:05 PM

      Hey Harry,
      When we did our shower pan in our second bathroom, we waited 72hrs to apply the RedGuard. After 48hrs there was little to no trace of moisture in the mud bed so we added an extra day, just to be sure.
      This was also at 65-70 degrees indoor temp.


      – Jason

  • Peter Bonnell September 30, 2016, 7:04 PM

    I try to use latex gloves when using RedGuard but often forget. When I do, I have found that Goof-off is the only thing that works to clean hands. Peel off the thick stuff and then use the Goof-off for the residual. It’s not perfect but it works.

  • Amanda May 1, 2017, 8:08 PM

    Today we were waterproofing a shower. My dad accidentally dropped a giant blob of redgard on my head. It dried in my hair. How can I get it out? 😬

    • Jason Esposito May 1, 2017, 9:10 PM

      Oh god, lol
      I can’t say that I have done that before, but mineral spirits took it out of my arm hair without too much trouble.

      – Jason

  • Mark May 26, 2017, 1:14 AM

    Hey, Jason, I just started working tile for my friend and wiped some of the goop onto my jeans. Got any suggestions on how to take it out of fabric?

    • Jason Esposito May 26, 2017, 8:48 PM

      Oh No!
      I unfortunately have not found anything that will remove Red Guard off of clothes. 4 years later and I still have unchanged blobs of it on my work clothes.

  • keith November 25, 2017, 2:01 PM

    Jason, how did you do the transition from the bottom of the Durock to the tub flange?
    1. Silicon Caulk?
    2. Alkaline resistant mesh tape and then RedGuard over that?
    3. Alkaline resistant tape and then thinset mortar and then Redguard over that?
    4. How did you tape and finish the transition between the top of the Ducrock (CBU) and the ceiling greenboard? (joint compound and paper tape, or alkaline resistant fibatape and thinset)

    Also, did you leave a gap between the CBU and the tub flange, or did you rest the CBU firectly onto the tub flange?

    Finally, how do you tape/seal around the water pipes protruding from the CBU into the wet area?

    Thanks Jason, my bathroom looks EXACTLY like yours. Light, window, tub, etc… Only thing I went with was a non-opening window and yours opens. I did this to eliminate additional avenues ofr water to get between the walls.

    • Jason Esposito November 26, 2017, 1:46 PM

      Hi Keith,
      Thanks you for your questions. I’ll be glad to answer them to the best of my knowledge and memory.
      The hardi-backer to tub overlap was a thick bead of 100% silicone. I ran the backer over the raised flange of the tub and stayed about 1/4″ off the bottom to prevent any wicking.
      For the top transition to drywall, I ended up tiling all the way to the ceiling joint which hid the seam. Then used white silicone in the small tile gap which allowed and seal and flexible transition between the various materials. In 4 years I don’t think I’ve ever had water even come close to that high, even with two crazy toddlers.
      The seal around the shower head was simple because the hole was so small. I was able to use silicone behind the decorative cover and never though about it again. The main valve and tub spout to a lot more time since I was determined to get the tile as close to pipes and valves as possible. I was able to use just silicone on the tub pipe. The hole was small and the tile was even smaller. I’ve had the back of the wall opened for a access panel and all still looks perfect back there. The valve was a little harder because the gap was so big. I got the tile close, but found that the Jacuzzi drain kit had an extra thick foam gasket that fit around the valve and sandwiched nicely behind the decorative cover. The cover also includes a smaller foam gasket on the outer edge that sits against the tile for another seal. I think there are much easier solutions out now from that German company that everyone is using Kerdi or something…

      Hope that helps a bit, cheers!

      – Jason


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