Don’t skip this essential tiling step
While you may be in a hurry to transform an old shower into a serene spa-like space with new tiles, there’s one step you can’t skip: waterproofing. Sure, grout and tiles may have some water-resistant properties, but they’re not completely waterproof. They require extra prep and finishing to stand up to long-term water exposure. Let’s dive into tile shower waterproofing, from prepping the walls to finishing with sealant.
Before you tile a shower, you need to waterproof it to prevent mold, pests, and damage to the tiles. Even non-porous tile and grout types require some extra steps, like laying a waterproof base and finishing the tile with sealant, to keep moisture at bay.
If you don’t take time for tile shower waterproofing, water and humidity will wear down the tile and grout. Eventually, the moisture can cause mold and mildew to grow on or under your shower tiles and potentially attract pests. Long-term water damage behind tiles can destroy your tile work and even cause harm to the walls behind the tile.
Installing tile in a shower costs $225 to $2,000 on average, and this price includes the prep work to properly waterproof the walls behind the shower tile before installation. However, if you plan to install your own tiles, you’ll need to budget $450 to $750 just for the supplies to waterproof the shower before tiling.
Before you start waterproofing your shower, check with your municipality for any building codes you need to adhere to before taking on a bathroom reno. Some cities may have building codes that specify what types of waterproofing materials can and can’t be used for tiling projects, so study up before you start installing a membrane. If reading the building codes leaves you confused, call a tiling pro for assistance.
There are multiple methods for tile shower waterproofing, including installing a sheet membrane, adding a foam board, and applying a liquid membrane, then finishing with a waterproof sealant. You may even want to use multiple methods for the most water-resistant tiling job. The more diligent you are during the waterproofing prep stage, the longer your tile will last. Here’s how to waterproof your shower tiles from the base to the sealant.
Although installing a sheet membrane can be tricky to DIY, this method offers excellent waterproofing qualities for your shower tile. To install a sheet membrane, use a trowel to carefully, evenly apply a coat of thin-set mortar on the walls. Apply the mortar in a flat layer, then use the ridged side of the trowel to create a notched pattern in the mortar.
Roll the sheet membrane out over the mortar, using the trowel to smooth out the sheet as you go. The sheet membrane should be entirely adhered to the mortar before you leave the mortar to dry for 24 hours.
Using a foam board instead of a sheet membrane is easier for DIYers because the extruded polystyrene foam material is lightweight. Use a trowel to apply notched thin-set mortar to the shower pan first, then the walls and the back of the foam board. Use sealant around the edges of the shower pan before and after installing the foam boards on the walls.
In addition to being easier to DIY, foam board also sets faster than sheet membrane. The foam board only needs to set for 30 minutes plus the time it takes for the sealant to dry.
Liquid membrane is used in addition to a sheet membrane or foam board. If you apply just liquid membrane, the waterproofing won’t last as long as it would when combined with other tile shower waterproofing methods.
Applying a liquid membrane is similar to painting. You can use a paintbrush or even a paint roller to apply a thin layer of liquid membrane. Paint the liquid membrane over seams, nails, and other gaps in the foam board or sheet membrane to seal any potential weak spots behind your tile.
After you install the waterproof base of your choosing and add the tile and grout, there’s an extra step you can take to further extend the life span of your tile work. Using a commercial grout sealer, seal the grout following the instructions on the label. Wipe away excess sealant and allow it to dry. Then, you’re finished with your tile shower waterproofing.
As part of your regular bathroom cleaning checklist, there are some chores to keep up with if you want your waterproofing work to last as long as possible.
Squeegee shower walls and wipe them dry daily.
Clean shower walls and floors every week.
Use cleaners that won’t break down or soften grout.
Use air vents or dehumidifiers to reduce moisture in bathrooms.
Hire a grout pro to inspect and deep-clean the grout once per year.
Reseal shower grout every one to two years.
If you have the time and skills, you’ll spend $450 to $750 for waterproofing materials for a shower, which includes sheet membrane rolls, foam board, thin-set mortar, liquid membrane, and sealant. However, if you make a mistake DIYing, you risk damaging your grout and tiles (not to mention the walls behind your shower), and the tile alone costs $5 to $45 per square foot to replace.
It’s best to hire a local tile pro to waterproof the shower before tiling and expertly install the tile in your shower. Professional tile installation and waterproofing costs around $400 to $4,250, and hiring experts means the work will be done quickly and correctly, leaving you with bathroom tile that looks as good as new for years to come.
Yes, you need to waterproof shower walls before tiling to prevent any moisture from leaking through gaps. If moisture gets behind the tiles, it can cause mold growth, attract pests, and even loosen the grout, leading to broken tiles. Not only that, but many cities require waterproofing shower tiles in their building codes.
While it’s still best to install waterproofing materials behind the tiles, you can still add better water protection to your shower without any demo work. Start by softening and removing old grout and installing new grout, then seal the grout and caulk the shower to help seal any gaps and prevent leaks.
Yes, mold can grow under your shower tiles if they aren’t thoroughly waterproofed. Even if you have a durable, non-porous tile material, water can make its way through grout or gaps around the edges of the shower. This will slowly erode the grout, which can cause tiles to come loose. It can also trap moisture behind tiles, and within a day or two, mold and mildew can rapidly grow.
