Tag Archives: durabililty

Step 3: Bathroom waterproofing

moisture management,

Because of the amount of water a bathroom handles, we should treat it like a big bathtub. In our case that bathtub has two drains. But that bathtub should also hold water – or more precisely, be waterproof.

The point here isn’t that we plan to fill our bathroom with several inches of water to go for a swim, but that we acknowledge that there will be incidental and accidental spills that could lead to water damage and durability issues if not managed properly.

I am a fan of “properly” and “proactively!” So our entire bathroom floor will be lined with a waterproofing membrane that we fold up on the walls by about four inches. It basically could be a shallow bathtub (except for the door, of course).

If we do our job right, no water from incidental or accidental spills or the walk-in shower would get past the waterproofing membrane and into the concrete floor and framing beyond.

But don’t relax yet, because there is a lot more to it! How many bathrooms do you recall where you saw cracked grout lines in the floor, or even cracked floor tiles?

A fact that comes with framed structures (in our case our floor joists) is that they move due to thermal expansion and contraction. And yes, we poured a concrete floor, but that won’t put a stop to material movement for a couple of reasons. First, we integrated radiant heat into the floor, which will lead to thermal expansion and contraction. Second, the concrete cover over the floor joists is thinner than elsewhere.

All this basically guarantees that there will be some level of cracking. It will probably be very minor, but enough to migrate up to grout lines or even floor tiles.

The waterproofing membrane we selected (NobleSeal TS) provides crack isolation. Small and hairline cracks in the concrete floor should not pass the membrane, and thus it prevents crack migration into the thinset tiled floor above.

Not only are the benefits aesthetic (i.e. no cracks in the tiled floor), but also maintenance related (i.e. no cracked grout lines to repair). And last but not least, there is the added benefit of durability. With an intact first layer of defense (tiles and grout) water is less likely to get down to the second line of defense, the water proofing.

In case you are wondering if this is all worth the effort, just talk to some contractors who have experience remodeling 100+ year old buildings. They possibly have some good horror stories on what even small water damage can do to a building over time.

Before I move on to step three, let me extend our sincere thanks to our friend Rubani who helped me wrestle the waterproofing membrane.

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Step 2: Bathroom drain flashing

moisture management,

All wet rooms, and this includes bathrooms, should have a floor drain. There are always spills, splashes, the sweating toilet tank, and maybe the occasionally overflowing sink. The floor drain should capture and manage that unwanted water before it can do any major damage and affect durability of other building materials.

We decided on two floor drains: one servicing the barrier-free, walk-in shower, and the second one (the main floor drain) catching any unwanted and occasional spills. The concrete floors are poured and sloped towards the two floor drains. The next task was to waterproof the floor drains. This was sort of a big deal, as the shower drain will and the main floor drain may receive a steady flow of water that should just go down the drain and nowhere else!

The good news was that I didn’t need to reinvent the wheel. There are various drain flashing options available that would do the job. We used the Schluter product in the basement bathroom and the Nobel product on the 1st and 2nd floor.

As you can see in the time lapse above, I had to adjust the concrete floor around the drain because I didn’t have the drain flashing tool available when I poured the concrete floors.

The drain flashing tool is a simple pre-cut piece of foam board that pre-forms the concrete floor to perfectly fit the actual flashing. If you use the Nobel product, plan ahead and have the flashing tool handy when you pour the concrete floor (the tool comes with the drain flashing). It will save you some time and make the process easier.

Last but not least, here’s a summary video of the installation:

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Step 1: Bathroom wall board

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I have mentioned what damage water can do to building materials. Using appropriate building materials (i.e. water resistant materials) is critical when it comes to durability. And despite the word on the street, or the marketing material, or what your contractor may tell you, the famous ‘green board’ has no place in the wet areas of your bathroom.

Think of wet areas as everything that is tiled. Green board is still a gypsum core with paper backing on both sides. And paper and water don’t mix. The board eventually could get compromised and grow mold, leading subsequently to indoor air quality (IAQ) issues.

I would recommend paying a few bucks extra and investing in cement board, which definitely is water resistant. How do I know? Well, the experts say so, and there is anecdotal evidence.

I have a little piece that has been sitting for a number of years in the garden, and it is still holding up just fine. Try that with a piece of green board!

Cement board was again our choice for the bathroom wet areas. In our case that was the shower stall, the area behind the toilet, and around that lavatory.

The shower stall will receive cement board almost reaching up to the ceiling. In the area surrounding the toilet and lavatory we limited the cement board to four feet above the floor. This way all wall areas that would intentionally or could accidentally receive water have a paper free, cement based and water resistant wall board. I also highly recommend to use special, alkaline resistant screws to attach the cement board to the framing.

The cement board will receive additional waterproofing and tiles, which should give us the reasonable amount of durability we are seeking.

More about the waterproofing and tiles in the coming posts.

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Bathroom strategies

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There are a handful of basic strategies that should apply to any new bathroom installation or remodeling. These should be common practice, yet they are not. Just recall the residential bathrooms you have visited and you’ll see what I’m talking about. With that in mind, it won’t hurt listing the basic strategies again:

  • Use materials that are appropriate for a wet room, i.e water resistant materials.
  • Properly waterproof your bathroom, i.e. the entire floor and any other wet areas.
  • Use tiles in all wet areas.
  • Use an isolation membrane between the tiles and substrate to prevent tiles and/or grout lines from cracking.
  • Use a corner profile or caulk at every change of plane (i.e. wall corners or floor to wall transitions) to allow for movement and prevent grout cracks.
  • All wet rooms should have a floor drain.
  • Pitch your bathroom floor towards the floor drain.

  • If you can’t pitch the floor, make sure your doorway sill is raised and sealed.
  • Use the proper drain flashing for your floor drains.
  • Use an appropriate grout, and keep sealing it. Or better: use an epoxy grout.
  • Properly vent your bathroom.

In short, it comes down to durability, proper moisture management strategies, and indoor air quality (IAQ) management. And even though some of these strategies will cost you a buck or two extra, they certainly will help you to save money and a lot of headaches in the long run!

And now, let’s get to work, step by step.

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The bathroom corner issue

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Once the Thinset mortar behind the waterproofing membranes has cured, we can start with the preparations for the bathroom floor tiles. We had thought about the tiling for a while already, but more on that in another post.

The plan was to start with the base tiles along the floor and wall edges. That lead us head on to a problem that I really wanted to resolve.

Corners in shower stalls are notoriously difficult to seal and to keep clean. This is where the water usually concentrates and soap residue accumulates. In an attempt to manage the concentration of water in those corners, they are often sealed with a bead of silicone, which in turn appears to be a soap residue magnet.

In short, these corners begin to look skanky really fast.

I am not the only one who has been bothered by this. Somebody else actually came up with a solution that makes the corners more hygenic.

This reversed quarter round or cove shaped profile by Schluter with a 18 mm (almost 3/4 inch) radius is made out of rigid PVC and prevents water from concentrating while being easy to clean. It comes in different depths that correspond to the tile thickness with which it will be used.

The anchoring legs of the profile are set into Thinset mortar. Once cured, the base tiles can be installed. They should end up flush with the cove profile to allow for good drainage.

This is one of these obscure gadgets that add to the longevity of an installation, make for a healthier indoor environment, and help with the moisture management.

To control costs, we only installed the cove profile in the shower stall, where it is most needed and most useful. Let’s see if it will do the job and meet our expectations.