The slab under your house is the stage on which everything else stands. Even a small tilt can invite cracks, sticky doors, and costly fixes. Before you call in help, you can do a quick level test on your own. The process is safe, cheap, and only asks for patience and care.
Gather Simple Tools
Start by collecting items you probably already have in a kitchen drawer or garage shelf. You will need a long, straight board, about six feet, a short carpenter’s level, a roll of masking tape, a pencil, and a small pad to record notes. If you do not have a full-length board, a metal straightedge or even a broom handle that has not warped will do.
Make sure the surface of whatever you choose is flat by sighting along its edge. Finally, give the floor a quick sweep so dirt does not throw off your readings or scuff furniture.
Find a Reference Point
Pick the spot inside your home that you believe is closest to the original floor height. A hallway near the center of the house is often a solid choice because interior areas shift less than outside corners. Place the longboard flat on the floor and set the small level on top.
If the bubble centers, you have a starting point. If it drifts, slide a thin playing card or piece of paper under one end until the bubble balances, then note the shim thickness. Mark this location on the floor with a short strip of tape labeled “zero.”
Check the Perimeter
From your zero point, move to the nearest wall. Again, lay the board and level on the floor, but this time, shim the low end with the same paper or card stack until the bubble centers, counting how many pieces you add. Write that number on the tape at this spot.
Repeat the routine every four to six feet around the room, then continue into adjoining rooms. Keep the board pointed toward the original zero as often as you can so your readings stay consistent. By the time you reach the far corner, you will have a simple height map.
Mark and Interpret Your Readings
After the whole floor is dotted with tape labels, step back and look at the numbers. Higher counts mean that the spot sits lower than your zero point because it needs more shims to level the bubble. Draw the numbers on a sheet of graph paper, connecting equal values with light lines; this picture quickly shows dips and humps.
A difference of one or two playing cards across a room is usually harmless. Gaps larger than a quarter inch should prompt closer watch. If you see a steady slope toward one side of the house, learn about professional help and modern foundation repair techniques before damage spreads and costs you more.
