What Are Best Ways to Waterproof Bathrooms

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Water damage to homes can be accurately expensive, and it’s not something you could postpone for a later time of the year when you have saved enough cash for the same.

According to HomeAdvisor, water-related repairs at home can cost you an average of $350 to $1200, depending on the material you choose to use when repairing. 

Other costs related to structural damage, mold and mildew handling, and repainting can become a costly nightmare if installation specialists do not waterproof the room before and after tiling.

The best way to waterproof your bathroom floor is to use a primer, a sheet membrane, or a combination of both, which acts as a bathroom seal to protect the floor from water penetration. You could use multiple layers of coatings applied in opposite directions for best results, preventing pinhole effects and air entrapments. 

Should bathroom floors be waterproofed?


The bathroom floor needs to be waterproofed. The insulating, protective layer will stop leaks, keep mold at bay, and make the house more saleable. Waterproofing isn’t that hard to achieve, but it can be expensive, depending on the materials and carpentry skills.

Waterproof flooring is usually made of polyethylene sheet membranes installed over concrete subfloors. It’s easy to install and remove, and it’s also inexpensive. However, it does require some skill to apply properly.

Pros and Cons of Waterproofing A Bathroom Floor

  • You won’t get sick from mold and mildew due to condensation.
  • This prevents leaks from causing damage and saves money on repairs. Suppose your toilet overflows or a pipe bursts. Rot won’t damage any wood structures underneath. Bathrooms upstairs need to do this!
  • During the cold months, waterproof flooring will keep your feet warm.
  • If you decide to sell your property, it can help increase its value.
  • Water-resistant flooring is less likely to be damaged by termites and carpenter ants.
  • As with many home improvement projects, the cost is the biggest issue. Depending on the size of your bathroom, this can cost up to $800.
  • During the curing and drying process, you won’t be able to use your throne room.
  • Even if you’re handy, it’ll still cost you time and materials. 

Ways to Waterproofing Your Bathroom

Each type of waterproofing has its pros and cons, just like any other building material.

Vapor Barrier

Making a bathroom waterproof starts with a vapor barrier. It depends on the weather where you live. Make sure you hire a professional if you’re gutting or remodeling the bathroom. In this way, you can make sure the right vapor barrier is used (like a polyethylene sheet or vapor-barrier paint).

Tile Walls

The best option for waterproofing a bathroom is to use tile backed by a cement board. Tiles should be used around the shower and tub. Water cannot penetrate tiles after they have been sealed. It will make it so much easier to clean and maintain your bathroom.

Cement Board

Shower walls and ceilings above the tub and shower should be covered with cement boards. Mold won’t grow on the cement board and it will last a long time. Bathrooms have a lot of water, so it’s made for places like that. The cement board can be painted any color as long as a thin layer of plaster is applied first.

Exhaust Fan

The job of the exhaust fan in your bathroom is to get rid of extra moisture, bad smells, and stale air. Excess moisture can cause mold and rot.

Silicone Caulking

When the vanity, walls, shower, and tub are finished, caulk all the joints with silicone. To ensure that the silicone sticks well, clean the area well first. Water cannot enter the cracks because of it.

Waterproof Paint

If you run a dehumidifier for a few days, the walls and ceiling will be dry enough to paint with waterproof paint. Put a coat of primer on first before you start painting.

Water-Resistant Flooring

Choose a flooring material for the bathroom carefully, as it will see a lot of moisture. This might be stone, ceramic, or vinyl flooring. Carefully consider these factors while picking up baseboards as well.

Sealing The Floor

After the flooring is installed, it’s time to seal it. Use a brush or vacuum to get rid of all dust and grime before sealing the floor. If you’re going with tile, pay attention to the grout lines, which are the most likely places to leak. 

How do you waterproof a bathroom floor before tiling?

Waterproofing the bathroom floor involves using a waterproofing system such as a sealer or a membrane on joints, grout, or the floor surface before tiling.

Follow these steps to waterproof the bathroom floor before tiling:

Step 1:

Begin by priming the surface and ensuring it is in good condition; it is clean, dry, and with less than 5% moisture content. By sweeping and collecting chips and small rock material, ensure the surface has little loose material. Shot blast the surface to increase the grip of the tile. 

Step 2:

You can then seal the floor by first applying a layer of a suitable floor primer. Ensure you cover the whole surface with a primer layer and that no spots are left. Allow the primer to dry completely. 

Step 3:

If corner pieces and joints exist, apply a silicone bead around the floor waist, the taps, and the row’s plumbing to allow for movement.

Step 4:

Apply another adhesive layer and place a 200-mm approved membrane on the curves, corners, and drainage systems. Ensure there are no wrinkles or air bubbles in the membrane. Push the membrane into the corners. 

Step 5:

Apply another second layer of coating to saturate the membrane before the first layer dries completely.  

Step 6:

For the best effect, you can use multiple layers of waterproof sealant applied in different directions to prevent pinholes and air entrapment. Ensure the coating has dried for 30-36 hours before fixing the tile.

How do you waterproof a bathroom floor after tiling?

Waterproofing a bathroom shower floor before tiling is not sufficient enough to hold back water. You could also waterproof the floor after tiling to ensure a foolproof seal.

This ensures no water gets underneath the tiles or into the first waterproofing layer. 

Waterproofing after tiling may also be necessary when you realize leakages into the adjacent structures. However, industry professionals do not recognize waterproofing after tiling as a sure method of waterproofing the floor.

Follow these steps to waterproof the bathroom floor after you have fixed your tiles:

Step 1:

You could begin by clearing some of the grout joints to prepare for the addition of a sealer. 

Step 2:

Use a ASTM C920 (American Society for Testing and Materials) sealant on the grout joints. Wait for it to dry before continuing with subsequent construction/operation processes.

Can You Tile Straight onto Waterproofing?

It’s safe to tile over waterproof membrane. Modern showers usually require a waterproofing membrane or waterproof backer board. There’s no need to prep the elastomeric membrane before tiling over it.

Always use a thinset mortar you’ve mixed yourself when laying tile over a waterproofing membrane. It’s a greater bet that this mortar will hold the waterproof membrane and tile in place than the pre-mixed kinds.

Liquid membranes, however, do not need any primer before tiling. They are painted, troweled, brushed, or sprayed over the surface. You can now tile directly onto the waterproofing membrane. However, use two layers of coating to ensure a continuous waterproof film.

Tile waterproofing sealers

Here are two tile waterproofing sealers recommended for their features.

1. Loctite Polyseamseal White Tub and Tile Sealant

Loctite Polyseamseal White Tub and Tile Sealant, 5.5-Fluid Ounce Squeeze Tube (2241860)
  • Possesses both bonding and sealing capabilities
  • Mold and mildew resistant seal
  • Scrub resistant; Sealant is watertight and paintable
  • Easy to use; Water clean up
  • 5. 5-fluid ounce squeeze tube
  • White  in color
  • Full Cure Time is 24 Hours

2. Seal It Green® Xtreme Impregnating Grout Sealer

Seal It Green® Xtreme Impregnating Grout Sealer-Non-Toxic And Zero VOC's-No More Ugly Black Stains, Food Stains Or Any Stains. Use On Granite, Grout, Tile & Stone. Seals & Protects. Easy To Use Pro Formula. Lasts Yrs.
  • Blocks black spot stains, dirt, and grime
  • Seals and protects grout, granite, tile, marble, and natural stone in showers
  • Non-toxic and zero VOC (no hazardous Fluoropolymer, Silane, or odors)
  • Easy DIY spray

Floor waterproofing membrane

1. Redgard® Waterproofing And Crack Prevention Membrane

Custom Building Products LQWAF1-2 1 Gallon RedGard Waterproofing & Crack Prevention Membrane
  • Ready-to-use elastomeric waterproofing membrane
  • reduces crack transmission in tile and stone floors
  • bonds directly to clean metal drains, PVC, stainless steel, and ABS drain assemblies
  • It can be used under all types of floor coverings.
  • Quick-dry formula
  • Recommended by IAPMO

2. Waterproofing Membrane material

Waterproofing Membrane for bathroom, shower and tile flooring | 3 Ft 3 inch x 33 Ft (1 meter x 10 meter) | 108 square feet | 8 mil thickness | Roll package
  • Enables tile installation directly on top of the membrane
  • Made of soft polyethylene
  • 108 SQ Feet large roll: 3′ 3″ wide x 33′ long (1m x 10m)
  • Crack bridging capabilities

Waterproofing a Wooden Bathroom Floor

Always waterproof wooden bathroom floors after the walls. You could use a urethane waterproof sealer that is water or oil-based. The sealer will protect the floor’s natural shine.

Step 1:

Apply the first coat of the sealer using a thick mop made of wool or any other soft natural material. 

Step 2:

Add a waterproof membrane to the floor. Add an extra layer of waterproofing agent so that it acts as an adhesive. This adds integrity to the sealer. Ensure you cover corners and crevices as you proceed. 

Step 3

Allow the membrane and the first layer of sealer to dry.

Step 4:

Apply another coating layer and let it dry before adding wooden flooring to your bathroom floor. 

Waterproofing Subfloor Before Tiling

Waterproofing methods used before tiling rely on the type of subfloor in the room you are tiling. The subfloor should hold the weight of the tiles and preparation materials required to complete the installation. Follow these steps to waterproof the subfloor before tiling:

Step 1:

Fill seams in the subfloor with caulk and tape off any affected vents 

Step 2:

Install cement-based backer board to prevent flexing of the tiles, and you can thus add the tiles.

Step 3:

Add a layer of primer before fixing the tiles. Use a flexible tile adhesive to increase floor substrate flexibility.

Pros and Cons of Waterproofing a Bathroom Floor


  • Saves you time
  • Protects your structure from water damages
  • Reduces home renovation intervals
  • It saves you money from repairing water damages
  • It prevents odors and mold, which are health hazards


  • It’s expensive to install waterproofing
  • Some waterproofing materials are not environmentally friendly

Do you Need to Waterproof a Concrete Floor?

Waterproofing concrete is easy. Because cement is porous, it can soak up a lot of water. Any concrete that will be submerged in water regularly, such as under tile or in a pool, needs to be waterproofed.

When the cement used between tiles is not watertight, mortar problems may arise. Sealants may be recommended based on the cement’s intended use. Sealers based on acrylic are acceptable for outside cement, while epoxy-based sealers are recommended for inside cement.

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