How do you waterproof a bathroom floor?

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Answer
To waterproof a bathroom floor, follow these steps:
  1. Prepare the Floor:
    • Ensure the floor is clean, dry, and free from debris or contaminants.
    • Remove any existing flooring and level the surface to ensure it is 100% flat23.
  2. Select Waterproofing Material:
    • Choose a suitable waterproofing material such as waterproofing membranes, liquid waterproofing compounds, or cementitious coatings. Each has its advantages and application methods, so select one that best suits your bathroom's needs and your skill level24.
  3. Apply Primer:
    • Apply a primer to ensure proper adhesion of the waterproofing material to the bathroom floor. Follow the manufacturer's instructions and allow it to dry completely before proceeding2.
  4. Seal Joints and Edges:
    • Use a waterproof sealant or tape to seal the joints between the floor and walls, paying special attention to corners and areas around drains or pipes2.
  5. Apply Waterproofing Material:
    • Apply the chosen waterproofing material according to the manufacturer's instructions, ensuring a thorough and even application2.
  6. Perform Water Test:
    • After completing the waterproofing process, perform a water test by pouring a significant amount of water on the bathroom floor and letting it sit for some time. Check for any signs of leakage or seepage. If there are any issues, identify the problem areas and make necessary repairs before proceeding with the installation of tiles or other floor coverings2.
  7. Install Tiles or Flooring:
    • Once the waterproofing process is complete and any necessary repairs are made, you can proceed with installing tiles or other flooring materials2.
By following these steps, you can ensure a waterproof bathroom floor that protects against water damage and maintains a safe and hygienic environment.




Author: Bathroom Remodeling Teacher



Key insights

  • Waterproofing is crucial for preserving the life of a bathroom and preventing issues like rotten wood and mold.
  • Rapid setting mud bed mix can be a quick solution for filling in gaps in the bathroom floor before waterproofing.
  • The best alternative for waterproofing a bathroom floor is to use a liquid membrane, creating a completely waterproof surface without seams.
  • ️ Using a half inch ruler can ensure that a copious amount of waterproofing material is applied to the floor.
  • I really like the idea of having waterproofing behind the vanity and toilet for peace of mind against any overflow or accidents.
  • Applying a thick layer of waterproofing around the toilet area can ensure that everything is 100% waterproof, eliminating the worry of water getting down the pipe.
  • 🧐 Applying a thick consistency of sealant on the bathroom floor is crucial to meet the required 15-22 mils per coat for a durable surface.
  • ️ It's important to apply a second coat to ensure the right mill thickness for waterproofing the bathroom floor.

Timestamped Summary

  • 00:00 Waterproofing a bathroom floor is essential for preventing issues like rotten wood and mold, and the choice of waterproofing system depends on the tile selection, while leveling the floor is crucial for installing small mosaic tiles.
  • 02:02 Use a rapid setting mud bed mix for waterproofing and Demetra for larger tiles, as smaller tiles require addressing seams for waterproofing.
  • 03:06 Use a liquid membrane to waterproof the bathroom floor for a completely waterproof and flat surface.
  • 04:21 Use a paintbrush, ruler, and film gauge to apply a thick coat of waterproofing product, embed mesh around corners, clean the floor, and then tile the walls.
  • 06:24 Waterproofing behind the vanity and toilet gives peace of mind and insurance against overflow or accidents, and using a waterproof system over concrete is recommended.
  • 07:53 Apply a thick layer of waterproofing mesh around the tub and toilet area to ensure 100% waterproofing and peace of mind.
  • 10:54 Apply a thick, consistent layer of sealant on the bathroom floor to ensure waterproofing.
  • 12:33 Apply two coats of waterproofing, but be prepared for a longer drying time before tiling.

Video Full Text

  • 00:00 So in this video, we're going to be waterproofing a bathroom floor, which I think is really one of the biggest and most important parts of renovating a bathroom is waterproofing. So whether it's the tub surround or the bathroom floor itself, it's something that's going to make sure that you preserve the life of the bathroom. All too many times, these old bathrooms, you tear up things and you see rotten wood, you see mold. And this is a really the way to prevent that. So in this particular situation, we had floor heating down because I really love floor heating and a lot of my clients do and we're going to waterproof it. And what I'm going to be using is a liquid waterproofing. Now there's many different systems to waterproof. We're going to go into the pros and cons of each and how to go about it, but it really comes down to the tile selection that you're planning installing. So let's get to the points and waterproof this bathroom. So first thing is we had this floor leveled so everything's 100% flat and which is really what I really highly recommend because, you know, when you get a six foot level down here and there's no space anywhere and you're nice and level, it works out really great. And for these small mosaic tiles, if you ever plan to do smaller tiles like this, it's imperative to have a really nice flat floor. So you can see on this six foot level, there's no space anywhere. Everything's 100% flat. So floor level, there is definitely the way to make it get you a little bit more precise with your installation. Now, after I removed, I used a spray foam all the way around the perimeter to keep that expansion contraction around and around the toilet. And I always recommend having a bag of feather finish on hand to be able to fill in areas, especially like against the tub or around your toilet supply. Another option you know, you might not know about the feather. Finish doesn't need to be prime and you can immediately use this, but it can only grow up to a half inch thickness. So if you had a thicker floor, you might want to go with something like this, which is the Arctic AM 100.
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  • 02:02 It's a pretty specific brand of stuff, but it's basically a rapid setting mud bed mix and it can go up to an inch and a quarter. So I always have these on hand as a contractor, just in case I need to fill something in really quickly. So I can move on with the waterproofing system. So once you have all these things established ready to go, then you can move on to the actual waterproofing system. So when it comes to waterproofing, there's a lot of different systems out there. This is probably one of the most popular. You've probably seen me install hundreds of feet of this here online on how to go about installing. Demetra is a great product and I really find it to be best for larger tiles. So a 12 by 24 plank tile anything with that larger size because in order to waterproof this you need to have a band that goes over the seams. Most of these products are only about a three foot wide, so you're going to have a seam somewhere within the bathroom and you're going to have to address to make it waterproof. And that scene is problematic for smaller tiles like this.
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  • 03:06 And a little bit of a deviation in hump is going to allow this to kind of raise up. And these things are not very easy to float thin said under if you kind of make it a little bit thicker, you're going to be fighting the thin set that's going to come out of the joints. So it really imperative to have a flat floor with the mosaics. So that's why I didn't go with Membrane or Deidre. Great products, just not great in this situation. The other alternative is to do something like a heat, which is a mat system similar to this, but allows you to float the wires within it. Problem is, they don't accept smaller tiles like this. Plus it's kind of similar to this where this waffle can be problematic to fill and be able to get this to be a nice flat surface. So the heat, that option was out as far as the heating system. So the best alternative next was actually just do a liquid membrane. Because this way I can roll the entire area, there's no seams and it's going to be, you know, basically kind of like a bathtub. It's going to be completely waterproof. And we're going to be using some of this mesh to go up against the corners of the room so that all of these areas around the bathroom are 100% waterproof.
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  • 04:21 All right. So the supplies that you need this pretty simple, not much different than painting, really a paintbrush to go around the edges, half inch ruler, half inch, so that you can make sure that you get a copious amount of this on the floor. This is not 100% necessary, but this is a film gauge to double check the thickness that you're actually putting it down by. Actually, just, you know, my Deidre or my Kurdi trowel is basically eighth inch. This kind of gives me a reference of it. But really, you just won't really want to make a nice, really thick coat of it. Will demonstrate that shortly. But you want to mix up the product before you get started. So this is actually something I've been using on many different jobs. I always have a bucket is on hand, but it's a pretty thick consistency. So just it's like a pudding basically. So I just mix this up a little bit, make sure that there isn't any surface water on top. I guess you could say. So then this is the mesh. This is what we're going to be embedding around the corners. And I'm actually going to do this first because you really should have multiple coats in the corners. So this is just a thin fabric that basically just gets embedded with the actual liquid membrane. So the thing you want to do is get all the dust off the floor, vacuum things up, wipe everything down with a damp sponge. You know, actually, let me just get the vacuum, because it is bad enough in here that I don't should have vacuumed in here earlier. Okay, so let's get some fabric. Let's go along the edge. All right. So really, this is really much different than painting, but you just want to get a nice, thick consistency of this on the floor and then embed that deal. So now these walls are going to be tiled as well.
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  • 06:24 But I really, really like the idea of having this waterproof behind the vanity and behind where the toilet is. Just, I don't know, it gives me peace of mind knowing that there's no way that any overflow or accident could get down to the floor below. So whether you're any type of system you're using, I like to do this just to be able to have that insurance, I guess you could say I'm not wearing gloves, but I should be because this stuff is kind of nasty to get off your hands. But I don't know what I did in my glove, so I just try to keep this flat and just embed another coat over top of it. Pretty simple, but this is great. I mean, this is a great system, forever concrete. You know, the only thing you're not going to really recommend. You still do is go directly on top of plywood because it's not going to be suitable for the expansion contraction or that you still have to kind of isolated. So whether that's cement board or the floor level or so, but going over concrete, this is a great way to do it.
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  • 07:53 I'm thankful I did this in my own bathroom, my kids bathroom, because it's amazing how much water is left over after a bath. And it's like this gives you peace of mind knowing that it's not going to get below it right now. The subfloor. Okay. All right. So this is a very nice area to make sure that you have good waterproofing. So we're going to make sure that we puts a mesh here. There's also many times I see a lot of rotten wood right at these intersections. Okay, so what we'll do is just basically put a decent amount right next to this tub. And what will I end up doing after this stuff? Dries is just basically caulking the tub to the waterproofing, and that'll be sufficient for this area. So the first coat really needs to have a where all the coats really need to be pretty thick and this stuff does uniformly dry pretty well. So don't be afraid to get a decent amount on here. This is definitely a critical area right along the tub. And like I said, we'll call this after this waterproofing. Whether your thing called. And then another great area that I think makes a lot of sense is right around the toilet area. So just caulking or just basically applying a thick layer around here because then once I tile everything, I can basically just cut the rest of the pipe and now everything's 100% waterproof around the toilet. You don't have to worry about anything getting down for this. Okay.
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  • 10:54 So the main floor, pretty easy to get a fair amount on the floor. And we're going to just roll it with the the half inch and a half roller. And I would say it's not really rolling. It's kind of pushing it as far as the thickness goes. So you want to definitely get enough on here to basically push this around, working it into the substrate. And then you can use one of these film gauges you need between 15 and 22. So anywhere within here you want to be able to scrape this and be able to see that filled with the sealant. So the other way, if you don't have this is really just to, you know, just try. To just. This is an eight inch by eight inch trial and you can see how I have it scraped up and it's kind of fill in there as well. So so a film gauge works or you can just use or try to gauge it. But really it all comes down to just making sure that you have a really nice, thick consistency on the floor because you really need to have 15, at least 15 or 22 mils per coat to be within their requirements. And that's just going to give you a durable surface. It's a good thing I have another bucket downstairs that I was going to, so this bucket wasn't full, but one gallon should do this and this was not four.
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  • 12:33 So, okay, so about an hour or two later, it'll be dry to the touch and you'll see this all of green. So we'll put a second coat over everything and then we'll be set at the right mill thickness to go ahead and do our tile. So that does take about 2 hours almost to completely dry. And then this is going to take another couple of hours to dry. So typically honorable to do this on the same day as far as tiling goes. So that's one drawback to this system, is that you're not able to get everything done in one day and set the tile.
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