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How to Build an Uneven Floor

Uneven floors slope from one side of the space to another, either intentionally or due to a structural problem. Interior floors may develop unevenness over time, which is why local building codes allow for a small amount of slope in older homes' floors. In cases such as bathroom showers, the subfloor is actually even with a sloped shower pan or mortar bed laid on top of it to allow for drainage. You can build an intentionally uneven floor for an outdoor building such as a shed or detached garage to make it easier to sweep out or hose down the space.

Things You'll Need

  • Carpenter's level
  • Gravel
  • Metal ruler
  • Thatching rake
  • Sand
  • Flooring material
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    • 1

      Lay a carpenter's level across the site for your floor at several locations to determine whether the ground is even. Building on even ground presents some complications, but allows you to easily build an uneven floor by installing it parallel with the grade. If the ground is even, you'll need to construct the slope yourself.

    • 2

      Lay a roughly 4-inch bed of gravel over the entire floor area, spreading the gravel out with a thatching rake.

    • 3

      Insert a metal ruler into the gravel at several points, pressing downward until it reaches the ground below. Spread the gravel with a thatching rake until it's 5 inches or more deep at one end, with an even slope that falls gradually until it's between 2 and 3 inches deep at the other end of the space. Take depth measurements with the ruler as you work, and to check the completed gravel base.

    • 4

      Spread 2 inches of sand over the gravel base, using the smooth back end of the thatching rake. Check the floor's depth with the metal ruler to ensure the sand is an even 3 inches and the gravel base retains its slope.

    • 5

      Install conventional flooring material over the sand base by piecing together interlocking flooring tiles or cutting a roll of flooring to the appropriate size. Add any drains or openings you have planned for the space near the lowest part of the floor to prevent pooling water, which can damage the flooring and uneven subfloor.