Should a Bathroom Floor be Level?

Whether you’ve just bought a house and are renovating or building something from scratch, you have likely heard of sloping floors in the bathroom. Uneven floors are not ideal and can cost a lot of time and money to fix when remodeling an older house. So, why should a bathroom floor not be level?

A bathroom floor should be level before installing tile or wood floors, as a solid subfloor is crucial for building a sturdy structure. However, it is not uncommon to see sloping floors in wet rooms and showers, as you need a slight slope to ensure proper water drainage.

This article aims to help you understand why bathroom floors need to be leveled and how to go about it. We will also discuss the difference between a level floor and an uneven floor, along with how to slope your bathroom around your shower area for efficient water drainage.

Do all bathroom floors need to be level?

In general, all floors in your house should be level, including the bathroom. However, not all bathroom floors need to be perfectly level.

To be more precise, while the majority of your bathroom floor should be level, your wet area – where you would place your shower – should be sloped to allow water to drain quickly and effectively.

What is the difference between a sloping, uneven, and unlevel floor? If the subfloor is not properly prepared, you will find that it can be uneven, sloping, or slanted in certain areas, which are all slightly different things.

While technically you can tile an uneven floor, you cannot do so with a sloping floor.

Here is a breakdown of each element and their significance for better understanding:

• Uneven floors: The flatness of the floor indicates how level its surface is, so an uneven floor will have any number of peaks, cracks, depressions, indentations, and uneven spots. Debris, dirt, and rocks can also make a floor uneven in certain areas.
• Unequal floors: Unequal floors are those that slope to one side, although this is usually unintended. Unlike the next point, these are more the result of poor installation rather than intentional design. Unequal floors are not necessarily uneven floors.
• Sloping floors: Sloping floors are similar to uneven floors, as they are inclined up or down on one side, but these are (usually) intentionally constructed. in your wet room, so that water can easily flow towards the drain.

While your bathroom floor should be flat and level, the floor in your shower enclosure or wet bath can and should be sloped. Under no circumstances, however, should your subfloor be uneven.

What is a subfloor and why should it be level?

Before installing tiles or hardwood planks, you should know that the surface technically called “floor” is not. The subfloor is the bottommost layer of your flooring, underneath which may be a layer of underlayment, padding, and carpet or hardwood.

The overall integrity of a good hardwood or tile floor depends on the quality of the subfloor. Think of it as laying the foundation for your flooring – Just as your home needs a solid foundation for long-lasting durability, so does your flooring.

An compromised, uneven subfloor makes it difficult to install tiles or carpets, so it needs to be done right the first time. And while you may add slope to your bathroom, it’s important to start with a solid and level subfloor to ensure it lasts for years.

How does an uneven subfloor affect flooring? Do you know the feeling of walking on a floor and hearing it squeak or, worse yet, sag? That’s the sound of an uneven subfloor giving way – or in some cases giving up.

If you’re tiling in your bathroom, if the subfloor is uneven, it won’t be long until the tiles give way and start to sink or crack.

If you have hardwood floors over uneven subfloors, that’s where the creaking starts. You will also get moisture that seeps through and collects between the gaps of your flooring and the uneven subfloor, leading to all sorts of issues, such as cupping. In this case, you may need to replace the entire floor.

Consider adding an underlayment to reinforce the subfloor and act as a vapor barrier.

How to determine if your bathroom floor is level

Are you familiar with the bottle test? It involves placing a bottle – sometimes a marble – on the floor to see if it rolls downhill on its own.

This method is not entirely accurate and while it may show you that you have an obvious slope in your floor, you should apply more accurate methods.

There are three methods to check if your subfloor is level.

Using a spirit level – First, you’ll need to invest in a carpenter’s box beam level like this SOLA Big Red Aluminium Box Beam Level, preferably one that is longer than 4 feet to check how level your floor is. The longer the level, the more accurate your measurement.

Follow these steps to see if your floor is level:

1. Place the level on the floor and move it around, taking measurements at various spots.
2. Measure any gaps that appear between the level and your subfloor.
3. If you have a gap less than an eighth of an inch (0.318 cm), your floor is mostly level.
4. A larger gap means you will need to level it.

Using a bubble level – Alternatively, you can use a DOWELL Magnetic Level Torpedo Level, which is shaped like a torpedo level.

1. Check the position of the level to determine if it lies between the two lines.
2. If it lies between the two lines, your floor is level.
3. If it is on either side of the lines, it seems that your floors are not level.

Using a laser level – The third method for determining the levelness of your subfloor is by using a laser level device on a tripod. The easiest would be using a self-leveling laser beam like this self-leveling cross-line laser from Bosch.

1. Place the laser on your tripod and then place the tripod on a surface roughly in the middle of the floor and turn it on. You will need to wait as the laser beam levels itself.
2. Once you’ve set up the laser and the tripod, the receiver will emit a series of beeps. If you hear a long beep, your receiver and laser beam are perfectly level. You will need to mark those measurements.

Note: During this process, you will need to move the laser receiver up or down until you get the desired measurements. When you actually level the floor, you will need to set your receiver to a predetermined slope and level the surface until you hear that long beep.

You can learn more by watching this video:

How to level your bathroom floor

It’s common to find sloping floors in old houses, sometimes they were simply laid that way, but sometimes it’s the result of an uneven subfloor that needs to be leveled.

Ideally, installing a subfloor is the best way to level a floor, but there can be inconsistencies, dips, or cracks that you’ll need to deal with underneath.

Let’s take a quick look at how to fix these issues.

Address any obvious dips and unevenness – Unevenness and depressions along your subfloor are deterrents to a smooth, level subfloor. How they will be fixed depends on how severe these unevenness and depressions are.

Sometimes, it’s as simple as scrubbing the area with sandpaper, while other times, you may need to purchase some mortar and fill in the gaps.

Learn how to repair unevenness and depressions.

Fill in any depressions or sunken parts of the floor – If your floor has a wide, trench-like depression sloping steeply toward the center, you will need to fill in the depressions or sunken parts of your subfloor.

Mix some modified setting mortar and spread it with a trowel on the floor. Remember not to use too much – just enough to level the surface. If you have excess mortar, scoop it off with a pointed knife or a sponge.

Grind down any high spots – Dips are not the only thing preventing your floor from being level – you could also have high spots that need to be ground down.

If it’s on a wooden subfloor, remove it with a belt sander. These are not excessively expensive, but if you have a large area, you may want to consider renting one from your local home improvement store.

If it’s on concrete, you’ll need a combination grinder and vacuum, which you can also rent from a larger home improvement store.

Level the floor with plywood – You can also level your floor with plywood, but this will only work if your floor is only slightly uneven.

Here’s how it’s done:

1. Measure the exact slope of your floor.
2. Cut leveling strips, which are long, tapered strips that gradually thin out toward the level area.
3. Position these strip on the floor and check if the top of the strip is level.
4. Cut more of these strips and attach them all the way down.
5. Use screws to firmly attach those leveling strips in place.
6. Install your plywood subfloor over those strips and nail it securely again.

Pro tip: Consider applying Zinsser 2301 Problem Surface Sealer after laying your subfloor. Dilute the primer and apply a layer of primer solution with a paint pan and roller brush in a similar motion to painting walls.

Using self-leveling concrete – Self-leveling concrete is a form of modified polymer cement known to flow very quickly across a surface, so it’s said to “self-level”. You can use self-compacting concrete, which is also highly mobile but relies on flow agents.

Application: You will need to pour the self-leveling fluid over the surface and then spread it evenly using a trowel or a CC975-01 power rake.

Support beams – An uneven floor can be as simple as a few unevenness along the surface, or it may be something more serious, like poorly installed beams.

If the existing beams are excessive for what your floor is supporting, you will need to secure new beams in place and support them by placing adjustable steel columns underneath.

Once your beams are securely in place, your subfloor is level, and you can attach your floors.

How to slope a floor for drainage

As mentioned earlier, the only time you might want to have a sloping floor in your bathroom’s shower area. Wet rooms are becoming increasingly popular, which often means larger areas with inclined floors to redirect water into drains.

Assuming you have a level and secure subfloor, here’s how to go about creating a sloping floor to ensure water drainage:

1. Lay down a waterproof floor membrane on your subfloor.
2. Once you’ve determined where your drain will lead, measure the distance from the drain to the point where the slope is supposed to begin.
3. Calculate the desired slope.
4. Shovel, pack, and tamp mud using a trowel until you achieve the desired slope.
5. Mix and pour your concrete mix over the sloped surface and let it cure.
6. Remember to wipe off any excess liquid with a sponge and use a straightedge to achieve the perfect, trimmed edge or slope.

You can learn more about sloping the floor for drainage.

Conclusion

A bathroom floor should and must be level, unless you intentionally slope or tilt the floor to allow water to drain. However, you always need to start with a stable, balanced, and flat subfloor that protects the integrity of your tiles or hardwood floors in the long run.

Similarly, your floor must be even and level, without any unevenness or gaps that can lead to cracking and denting in your flooring.