Want to Fix Those Sagging Floors and Level Your House? Here’s How It’s Done

A guide to leveling your house

Co-authored by Johnathan Fuentes

Last Updated: October 12, 2024 Fact Checked

Is the lower floor in your house starting to sag? Houses naturally settle over time, but luckily, they can be leveled. This simple guide will give you an overview of how to level your house plus safety tips and tool recommendations. Keep in mind, though, that this may not be a DIY project unless you have structural engineering and construction experience. If not, you're better off hiring out this job—it's a big one!

Leveling a House

Use a laser level tool to measure how far the floor needs to be lifted.
Stack cinderblocks or wood planks below the lowest point of the floor. Place a 20-ton bottle jack on a steel plate on top of the blocks and raise the house.
Place blocks under a nearby floor beam to support it. Remove the jack and repeat the processes at other low points until the floor is level.

1

Have a qualified structural engineer inspect your home.

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A structural engineer can determine if it needs to be leveled, how soon it should be done, and the best method for doing so. They can also explain what’s causing the floors to sink and whether extra repairs might be needed once the leveling is complete. In some cases, they might be able to estimate the cost and time it might take to complete the leveling.^{[1]
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- An engineer might recommend having professionals level your home.
- In some cases, leveling a home yourself can cause more damage. Be extremely careful—and when in doubt, hire someone to do the job for you.

2

Buy or rent a hydraulic bottle jack from a hardware store.

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You’ll use this jack to raise the part of your floor that’s sunken. Be sure to rent a 20-ton jack or larger, since smaller jacks can’t support the weight of a house.^{[2]
X
Research source} You can rent a 20-ton hydraulic bottle jack for just $20 per day before taxes.^{[3]
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- The tonnage refers to the lifting force, not the weight of the jack. So an 8-ton jack can lift up to 8 US tons (about 7,200 kg), while a 20-ton jack can lift 20 US tons (about 18,000 kg).
- Use a larger jack for better lifting power.
- Unless you plan to use the jack for many future projects, you’re better off renting than buying one. A hydraulic bottle jack can cost thousands of dollars.^{[4]
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3

Use a laser level tool to determine how much to raise the floor.

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Place your laser level tool on the ground underneath the lowest floor in your house, or on the floor of your basement if your house sits directly on its foundation. Point the laser in a straight line from one side of the foundation to the other. You should see the laser on some of the floor joists. Measure the distance from the laser beam to the bottom of the floor joists, repeating this process in several locations until you find the lowest point the house has sunken to.^{[5]
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- If you don’t have a laser leveling tool, you can rent one from a hardware store.
- You can also use taut string or a water level tool, but these are less accurate and not recommended.

4

Mark the lowest point on the lowest floor of your home.

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The lowest point is the point with the longest length between the bottom of the floor joist and the line cast by the laser beam. Repeat the process to mark the second-lowest point, where the floor has sunken down slightly less.
- If you find two points that are equally sunken down, you can mark them both to add support in both locations.

5

Place wood planks or cinderblocks under the lowest point.

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Find a support beam directly under the lowest point, or as close to that point as possible. Then place the blocks under a floor beam, stacking enough so that the jack can sit on top of them, with roughly 1 inch (2.5 cm) of space or less between the top of the jack and the floor beam above it. Put a ¼ inch (0.6 cm) thick steel plate on the top block, then place the jack on the plate to prevent the jack from crushing the wood.^{[6]
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- Use wood blocks or planks at least 1 inch (2.5 cm) thick. Always place a steel plate on top of them to support the jack.
- Make sure the blocks are stacked on firm, level ground under the house.
- If the support blocks are rectangular, you can alternate the placement of each layer of blocks by 90 degrees to make the tower more stable.

6

Press the jack leaver down repeatedly to jack up the house.

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Keep jacking up the house until the height where you are jacking equals the height of the next lowest point in the floor above. Then use a tape measure to measure the distance between the second lowest point and the ground below.^{[7]
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- The heights may not match exactly. This is fine, as long as the lowest point has been raised close to the height of the second point.
- For added protection, wear a worker’s helmet and safety glasses when using the jack.

7

Cut another post to fit snugly under the second-lowest point.

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This will be a temporary post. For stability, use wood posts measuring 4x4 inches (10x10 cm). Then slide this temporary post under the second-lowest point to support the floor above it. Release the jack to allow the house to settle back down, supported by the temporary post.^{[8]
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- For added stability, cut 2-3 temporary posts and place them near the area of the second highest point. This will distribute the weight of the floor over multiple posts.
- Before continuing, check your house for damage caused by raising. Look for cracked walls, fallen bricks, and doors that seem to get stuck when they’re opened or closed.
- Don’t continue if you see any serious damage.
- If you spot problems like these, have a structural engineer assess the situation. You may need to hire professionals to finish the job.

8

Put another temporary post where the jack was located.

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Measure the new distance between the support beam and the ground below. Add cinderblocks or cut a post to that length and slide it in place.^{[9]
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- Use wood posts measuring 4x4 inches (10x10 cm).

9

Repeat this process with each area of the floor that’s sunken.

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Each time you raise the house, you’ll need to cut new temporary posts to support the floor. Measure and cut your posts so that they fit snugly between a support beam above and the ground below. Repeat the process until the entire floor above is level.^{[10]
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- Use your laser level (or other measuring tool) to check that the floor is becoming more level.
- As you raise the house, shorter support beams won’t be tall enough and may fall over. Replace these by measuring and cutting new support beams to ensure the floor remains supported.

10

When the floor is fully level, add permanent posts.

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These permanent posts can be made of cinderblocks or wood and will support the floor at its new height. Measure the height from the ground to the support beams above. Cut wooden posts to that exact height, or stack cinderblocks and add planks of wood so that they fit snugly between the beams above and the floor below. You can leave some of the temporary posts in place, as long as they aren’t too short to support the floor.^{[11]
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- Add at least 4-5 support posts, spaced equally far apart from each other. The more posts you add, the more stable the floor will remain over time.
- Use 4x4 inch (10x10 cm) wooden beams for your permanent posts.
- Make sure to remove the jack, wooden blocks, and any leftover temporary posts that are too short to support the floor.
- Check water and gas lines in your house to make sure they weren’t affected by the raising.

Community Q&A

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Question

Can I build up my base plate on my kitchen wall foundation without leveling the back of my house first?

Community Answer

Theoretically you can, but the concept is that if you do one side and the other later, it will put more stress on the un-leveled side. While it is possible, it is best to get the lowest side up higher first, then lift the sides that are more level. If the base plate on your kitchen is the most un-level, you would be fine starting at that point until it is brought up to rough level with the rest of the un-level areas, then proceed leveling all areas slowly.

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Where should I begin the process of leveling?

Community Answer

Start at the highest point of the house, and work your way to the lowest, leveling as you go. Use a water level to determine.

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Question

How long can I leave a stabilizer jack post in place in a mud basement with proper footing?

Community Answer

Probably not very long. You may want to lay a few inches of concrete down, first. Otherwise, it's just going to sink into the floor and not support anything.

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Tips

Give the house time to "settle" after a series of small moves before proceeding to the final position.

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Signs that your house needs to be leveled include sunken floors, cracked or leaning walls, and doors or windows that won’t open easily.

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If you don’t have a bottle jack available, substitute a screw jack.

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Warnings

Be aware of water and gas lines in the house. Check them after leveling your house to make sure everything is working properly.

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Leveling a house can cause other problems including plumbing leaks, cracked walls, and roof leaks, among other issues.

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Wear a helmet and safety glasses for added protection.

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Sometimes, doors will not close properly after a house has been leveled. Use an electric planer on the doors in the spots where they rub against the doorframe.

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Using hydraulic jacks can be dangerous. A jack can slip, causing heavy objects to fall.

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