Do you have to waterproof the whole bathroom floor?

Author: Prof. Gust Hudson  |  Last update: Wednesday, June 11, 2025

The entire floor should be waterproofed for the shower area, and the shower walls need waterproofing up to 1800mm. Bathroom walls need waterproofing up to 150mm. For wooden bathroom floors or bathrooms on higher levels, the entire bathroom floor needs waterproofing.

Do I need to waterproof the entire bathroom floor?

Yes, it is essential to waterproof your bathroom floor before tiling to ensure that your bathroom is well-protected against water damage caused by leaks or seepages.

Do you need to waterproof a bathroom concrete floor?

Waterproofing your bathroom concrete floor is a necessary step to ensure the durability, safety, and aesthetic integrity of your space. Ignoring this critical aspect can lead to costly repairs, health risks from mould and mildew, and a decrease in property value.

Is it OK to leave bathroom floor wet?

If you don't wipe up after yourself or put a towel or something down to step on or wash over, that water can stand there and breed more bacteria already on the bathroom floor. In some cases, it can get under the trim and cause damage to the floor or take up stick-down tile if it happens a lot or stays wet too long.

Should you seal a bathroom floor?

Porous materials, like travertine and other natural stone tiles, often require sealing, especially in high-moisture areas like showers or tub surrounds. Conversely, for porcelain and ceramic tiles, which are highly resistant to water, sealing may be optional, especially for those that have a glazed finish.

How To Waterproof Your Bathroom Floor - DIY At Bunnings

Do you need to waterproof the subfloor in a bathroom?

That's because bathrooms are wet areas, which means they're more prone to water damage than any other room. The National Construction Code (NCC) requires all wet areas in a home, including bathrooms and laundries, to be waterproofed.

Should I caulk around bathroom floor?

Bathrooms. In a bathroom, you need to caulk in the area where the shower or tub meets the surrounding floor and wall. All of the interior joints within your shower need caulking. If you have more than one piece of wall or floor that surrounds the shower, you might also need to add caulking to the corners.

Can water seep through a bathroom floor?

Tile flooring is designed to handle water, but it's not completely waterproof. Over time, grout can wither away and cracks can form, creating the perfect entrance for those accidental spills to seep into. Water that gets under your tile can lead to all sorts of problems, including mold growth. More on this below.

Where should you waterproof in a bathroom?

How To Waterproof Your Bathroom
  • Shower floors must be waterproofed while walls are required up to 1,800mm.
  • Bathroom walls must be waterproofed up to 150mm.
  • The shower step must be waterproofed up to at least 100mm.
  • The entire floor must be waterproofed if the room is not on the ground floor.

How do I protect my bathroom floor from water?

Make sure the subfloor is wax-penetrated, which can help seal moisture out. Choose a flooring with a back sealing and one that interlocks instead of using nails. Use the right adhesive for bathrooms that will stand up to the added moisture. Check with your plumber to get the right height of the toilet flange.

Do I need a moisture barrier and a bathroom floor?

Regardless of your environment, you should consider using a moisture barrier in basements and crawlspaces as well as beneath flooring and behind the drywall in high-moisture places like kitchens and bathrooms. It's better to be safe than sorry when moisture damage could put your home's structural integrity at risk.

What happens if you don't waterproof concrete?

Concrete seems solid enough, but it's actually porous. Some of that water is bound to seep through, especially during heavy rains. Normally, there isn't enough seepage to form standing water on the floor. But there's often enough to increase the humidity, and that promotes the growth of mold and rot.

How do you seal a concrete bathroom floor?

How to seal your concrete floor
  1. Strip any existing sealer from the surface.
  2. Use an etching solution to open up the concrete.
  3. Apply a thin coat of the sealer using either a sprayer or roller.
  4. Leave the first layer of sealer to dry.
  5. Apply a second coat of sealer in the opposite direction to the first.

Do you need to waterproof a concrete bathroom floor?

Waterproofing your concrete floor before tiling is critical to ensure the durability and longevity of your tiled surfaces, especially in moisture-prone areas like bathrooms, kitchens, and outdoor spaces.

How do I keep my bathroom floor from getting wet?

Install anti-slip floor mats

Keeping a bathmat outside of your bathroom is an elegant solution. They will absorb the excess moisture from your feet.

What is the best waterproof flooring for a bathroom?

In terms of withstanding moisture and humidity, luxury vinyl tiles (LVT), vinyl roll, and porcelain or ceramic tile are the best bathroom flooring options. Each of these flooring options is water-resistant and able to withstand humidity and temperature changes in a bathroom.

Where should the waterproofing be installed?

Waterproofing should be applied over all exposed substrate surfaces, particularly concrete. Membrane under pressure slabs on the ground can extend under the foundation walls and over the pile caps. Foundation waterproofing must extend above grade a minimum of 8 inches.

How long after waterproofing can I tile?

Once the waterproofing membrane's been installed – and after it's been left undisturbed for a couple of days to properly cure – it's time for the tiles to be put on wherever they're required.

Where does a vapor barrier go in a bathroom?

They are often installed behind the drywall and around plumbing fixtures to prevent moisture from penetrating the walls and causing mold growth.

Can mold grow under ceramic tile?

If you notice black, blue, green, or pink growth appearing in water-prone areas (most commonly your grout), it's a sure sign you have mold issues. Mold will also grow under tiles, weakening their hold and lifting them. Loose or uneven tile can be another sign of mold.

What happens if water gets under waterproof flooring?

Warped and Buckled Planks: One of the primary consequences of water seepage is the warping and buckling of vinyl planks. When exposed to water, the core material of the flooring can expand, causing the individual planks to warp and lift.

Is it bad to leave bathroom floor wet?

Over prolonged periods, this moisture can lead to warping, peeling, or even structural issues underneath the tiles or floorboards. Additionally, the constant moisture creates a conducive environment for mould growth. These pesky fungi, aside from being unpleasant to look at, can pose health risks.

Should I caulk around the vinyl plank flooring in a bathroom?

For all vinyl edges exposed to the toilet flange or shower edge, you must properly seal them using silicone caulk. This will help avoid water from building up underneath the floor and potentially leading to not only mold issues but also weakened flooring from water saturation.

Is silicone or caulk better for bathroom floors?

Silicone caulks are the most recommended type for this application due to their flexibility, water resistance, and mold resistance. Choose a silicone caulk or sealant labeled specifically for bath and shower use for optimal durability and performance.

How to seal a bathroom subfloor?

You can seal a subfloor using a sealant specifically designed for subfloors, such as a penetrating sealer or a moisture barrier. Penetrating sealers are typically made from a wax or oil-based formula that soaks into the wood, protecting it from moisture and rot.

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