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wikiHow to Relevel a Sunken Floor

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Tired of that sunken floor in your house? Wanna Know how to fix it? Here are the simple steps to take to fix that floor yourself.


  1. 1
    Determine where the floors supports are. Is there a crawl space or basement below the floor? If there is a crawl space, then you will have to work with the jacks while laying down. If it's the basement, then jacks while standing up.
  2. 2
    Put a level on the floor in several different positions in the affected room to determine which way the floor is leaning.
  3. 3
    Check the perimeter of the room to see if there are any additional areas that are out of level. Draw on some paper a floor diagram and indicate what direction the floor is leaning. This will help a lot when the jacking begins.
  4. 4
    Get the jacks under the floor. Generally there are posts and beams under the floor joists. If a pier that the post is standing on has sunk into the ground you will need to lift the beam off the post and replace the post with a taller one.
  5. 5
    Place a couple of two foot long pieces of 2X6 lumber side by side on the ground under the beam and place a 3/4" plywood 1'X1' on top of the 2X6's. Place the jack (I prefer at least 25 ton hydraulic. or a house screw jack) on the plywood and then I use a piece of thick hardwood between the jack's ram and the beam to prevent damage to the beam. If two beams meet on the post that is sunk then a jack on both sides of the post is required.
  6. 6
    Begin jacking up the beam or beams and make sure you jack equally with two beams. Check the floor regularly to make sure you do not over level it.
  7. 7
    Look for low areas. Once the floor is brought to level you check all around to see if there is any other areas that are still low. This is done by placing the level on the floor in several different positions and areas as before.
  8. 8
    Remove the old post and measure the distance between the beam and the pier. Cut a replacement post of the same dimension lumber that was removed. You can go larger lumber but never smaller. But the best is to go with the same dimension. Also it is not a good idea to try to raise the pier block up by placing more dirt under it and then putting the old post back in. You aren't going to be able to compact the soil enough to keep it from sinking back down under the weight of the house.
  9. 9
    Place a piece of tar paper on top of the concrete pier and the new post on top of the paper. This will ensure moisture doesn't come up through the concrete and get to the wood. If the reason the floor sank is due to a rotten post and there was no tar paper you can now see what happens. Now put the weight of the house on the post. Keep it lined up with the sides of the beam. Check the floor for level again to make sure you're still good.
  10. 10
    Fasten. Once the post is replaced it needs to be fastened to the beam. If the beam and the post is the same width (they should be) then just nail a 2X4 piece on both sides of the beam down the side of the post and nail to the post. Then you fully remove the jacks and lumber they sat on and put them away. You're done!

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    • It is always a good idea to enlist the help of a friend with this. Two people can get this done faster but one can surely get it done by themselves.
    • If you are in a basement and lifting from a concrete floor you should also build the temporary pier to lift from. That will spread the weight out over a larger area and keep the jack from cracking the floor. Also you will need pole jacks to lift with to be safe. They can be rented from the tool rental stores.
    • Make sure you have plenty of scrap lumber to build your temporary pier pads for the jacks. I have pushed temp piers into the ground over a foot on some soft stuff in the past. So you have to keep stacking more lumber under the jack till it will lift the house.


    • Take care to make sure the jack has a level pier when lifting. If it is not level it can jump out from under the beam from the pressure. If it is level it will not move. Also the jack must be pointing straight up and down.

    Things You'll Need

    • 4' or longer level
    • 25 ton jacks or house screw jacks
    • scrap lumber
    • note pad
    • replacement post material (pressure treated is best)
    • tar paper

    Sources and Citations

    Article Info

    Categories: Floors and Stairs

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