Step 5: Bathroom waterproofing walls

The principles behind waterproofing some of the walls in the bathroom are the same as those for waterproofing the bathroom floor. Rather than repeating them, I would like to direct you to the recent post: Bathroom waterproofing.

That said, there are a couple of subtleties that are worthwhile pointing out.

A good strategy to manage accidental and incidental water spills in your bathroom is to use water resistant materials and waterproofing in all wet areas. Here is what I said about wet areas earlier: “Think of wet areas as everything that is tiled.”

The entire bathroom floor is part of the wet area. It will all be tiled and has a waterproofing membrane. I used a bathtub analogy earlier: “Because of the amount of water a bathroom handles, we should treat it like a big bathtub”.

Waterproofing the floor makes for a very shallow bathtub, and doesn’t address the other vertical surfaces (walls) in the various wet areas of the bathroom. We need to raise the rim of our tub. But what are those other wet areas?

Two out of the three water sources in the bathroom are the sink and the toilet.

The walls surrounding both the sink and toilet are part of the wet area.

They should be furnished with cement board and waterproofing up to a safe splash height of around 44 to 48 inches.

The third water source is our barrier free – or – walk-in shower. This area will not just receive incidental or accidental spills–it will be exposed to water on a daily basis.

The walls surrounding the walk-in shower on three sides are furnished with cement board and will receive waterproofing.

Even though we plan to put a cabinet beside the shower, and protect it with a shower curtain, we decided to extend the waterproofing behind the cabinet just in case it may be removed sometime in the future.

The one lesson I took away from this exercise is that it is a excellent idea to have a time lapse camera going so you get to learn how your wife really feels about waterproofing the bathroom with you! 😉

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About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

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