How to Level a Bathroom Floor?

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One of the most important steps when installing a bathroom tile or marble is leveling the floor.

You have to make sure that the subfloor foundation is properly leveled. Leveling the floor is important to reduce the gaps between the floor material and the substrate.

Whether the bathroom is large or small, the method to level the floor remains the same.

How to Level a Bathroom Floor?

In this article, you will learn about some tips to level the bathroom floor for proper installation of the tile, hardwood, lamination, or any other floor material you would like to install.

Step 1. Determine the Unevenness

You have to measure the high and low spots to determine the unevenness of the floor. Stretch a chalk line across the bathroom floor with both ends held in place on the floor. You should now try to find and mark any humps or dips in the floor.

Continue to use the caulk line to reveal the unevenness in the floor. You should move the chalk line around the entire bathroom to find the dips and humps.

You will have to get your head close to the floor to look for the uneven spots on the bathroom floor. Mark the spots where the humps and dips begin and end as you move the chalk line around the floor.

Step 2. Repair the Uneven Area

The next step to level a bathroom floor is to repair the high spots that you have determined using the chalk line. You should follow these tips to level different types of bathroom floors.

1. Leveling a Wood Subfloor

Screw down any loose plywood sheets or boards before leveling the wooden subfloor. You may have to use more screws to secure the loose subfloor. If nails have popped up, you should replace them with a screw.

You will have to sand down high spots to level the hardwood floor. Wear a mask when sanding the floor as it will create a lot of sawdust. Moreover, it is recommended that you tape plastic sheets over the air vents and doors to avoid the spread of dust

Now, sand the humps or high spots using the sander. Check the Home Depot for rental tools required for sanding the floor. You should level the high spots that you had identified using the chalk line.

After you have finished sanding the area, you should clean the floor using a broom or vacuum cleaner. Inspect the area again using the chalk line to ensure that all the humps are gone.

To remove the dips or low spots on the hardwood floor, you can an underlayment. The underlayment is a thin layer of material between two other materials. Installing an underlayment will not just fix dips but also serve as a sound and moisture insulating material.

2. Leveling Delaminated Subfloor

A bathroom floor made of a hardwood may become wrapped and deteriorate over time. Leveling the delaminated floor is difficult. You will have to replace the damaged floor panel to level the floor.

You can buy subfloors made of plywood or oriented strand board (OSB). These materials are made of wood fibers that are glued and pressed into panels. You will have to install an insulation material to protect the wood from delaminating again due to exposure to moisture.

Replacing a damaged subfloor to level the floor is a DIY task that requires basic construction skills. Consider buying a 4x8x4 sheet of plywood or OSB subflooring that cost between $18 and $24. It is best that you remove the entire sheet that is damaged instead of repairing sections of the floor.

3. Leveling a Cement Floor

You must use a concrete grinder if you have a concrete floor. A concrete grinder is recommended for open areas. For a small bathroom, you can use a 4-inch angle grinder with a cup wheel attachment.

Remember that grinding the cement will create a lot of concrete dust. So, you should wear a respirator to avoid inhaling the harmful dust. A dust mask will not be enough to avoid exposure to cement dust.

Grind all the high spots that you just marked on the floor. Check the area again using the chalk leveler to find out any more humps and dips. You must vacuum the floor or sweep it using a broom to remove the cement dust.

Next, you have to fix the low spots on the cement floor. You can use a cement-based floor leveling mixture for this purpose. The cement-based product can be dry or premixed with water.

Pour the flour leveling mixture as per the instructions of the manufacturer. You may have to use a damp sponge to wet the floor before application of the product. This will prevent it from drying quickly as you spread the mixture across the floor.

After you have poured the liquid over the subfloor, you must smooth it out using a trowel. The liquid will settle in the low spots on its own. Feather the liquid around the edges so that it matches with the rest of the concrete floor.

Let the floor leveling product dry for about 24 hours or as instructed by the manufacturer. Once the product has dried, you must clean the floor and do a final check using a chalk leveler.

Another method to fill the dip is to use a floor patch. You can use the floor patches to repair cracks, holes, low spots and other imperfections on the concrete floor. Read the manufacturer’s instructions to know how to properly apply the floor patch to level the dips or low spots on the concrete floor.

4. Leveling a Marble/Tile Floor

You should check the marble floor for the floor joist that bows upwards, creating an uneven heaved area on the floor. This usually happens when the floor joist bows upwards. This is a structural issue that can be resolved by removing the floor over the bowed joist and then leveling the joist across the top.

You should pop a chalk line on the side of the joist from one end to the other. You can then see the raised point of the joist. You can use a power planer to level the high area of the joist. In addition, you can also level it using a manual planer by hand. This will take more time and effort since you have to use manual power.

5. Leveling a Hardwood Floor with Wrapped Joists

Hardwood bathroom floor may twist over time creating an uneven floor. This may happen if the floor joists were incorrectly installed. The only way to level the floor with wrapped joists is to shim the joists and remove the subflooring.

You will have to attach a wedge-shaped or thin piece of wood on top of the joists to make them even. It will require using a laser level to determine the low areas with precision. You must attach the shims while working on the bare joists by screwing them. You should then level the area by removing the high spots.

Most homeowners call the pros for shimming the joists when required. The cost of the project ranges between $5,000 and $10,000. You can save this cost if you have basic construction experience by using the DIY steps described above.

A bundle of shims containing 42 items costs just $5. It will be more time-intensive buy you can save thousands of dollars in repairing the floor.

6. Leveling Old Bathroom Floor

Old bathroom floors commonly have joists that are spaced far apart. This was the case before the introduction of uniform building codes. Some builders had used lumber that was undersized when building the floor joist system. This resulted in a saggy and uneven floor.

Leveling the old bathroom floor will require a technique that is known as sistering the joists. The process involves attaching new joists to the existing ones. This will add strength to the floor that will make it easy to level the floor.

Sistering the joists is not a DIY task. It will require the expertise of a structural engineer. The new joists will have to be bolted to the old ones and joist ends will be positioned on the sill plate supporting the original joist.

This is a costly project that will cost about $5,000 or more depending on the number of joists require for sistering. The cost will be more if wiring and plumbing will have to be relocated to attach the sistered joints.

Final Remarks

You should be able to level the floor by following the steps in this article. Safety should be a priority when leveling the floor. You should always wear a mask when sanding or grinding the floor to avoid health problems.

Also, you should remember that even after you have leveled the bathroom floor, structural problems can still cause foundation movement. As a result, the floor will again become uneven and cracks may appear on the floor.

The lateral pressure from the soil will also cause the floor to sag and shift. To avoid this problem, it is important that you get the structural issue inspected by a certified structural engineer.

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