Expand Your Living Space – Dig Out a Basement in an Existing House

It wouldn’t be great to increase your living space without being forced to build a new addition. It would be very easy to do it, but only under one condition. If your home is built into a hill and has a basement from two parts, one with a standing floor and a comfortable height and the other one is sloped, going up to the hill.

Photo by Sanders Pace ArchitectureMore basement ideas

Before start, take all necessary precautions.

1| Check with your local authorities for construction permit.
2| If you are living south of 40 degrees North latitude, your home may be exposed to termites. Therefore, check with the pest control how to treat the ground before starting the work.

What can be removed from footing

Do not disturb the footing, where the slope is 45 degrees. If the slope is below 45 degrees dig in and leveled the floor. Remove the dirt outside. The floor has to be flat and 4 inches below the footing.

Flooded Basement Cleaning Tips | How To Build A House (howtobuildahouseblog.com)

Prepare the new floor

Use only pressure-treated wooden posts.

1| Lay down 4×4” along the length of your basement. Keep a distance of 6” between them. They will be the footing of your new floor.
2| For mold prevention, cover the entire area with a polyethylene (4 to 6 ml thick). One side of the polyethylene 3” up on the hill and the other three sides 1” up to the basement walls.
3| Time for joists. Place pressure-treated 2×6” floor joists across on the 4×4”.
4| Keep a 16” to 24” distance between joists. Nail joists to the posts.
5| Now, you need to construct a deck with a short wall where it was the slope; use plywood for a nice look.

Dig under the stone footing

In addition, many houses are built on stone foundations. Digging under this stone footing and replacing the stones with concrete, you can earn more in the basement height.

1| Break up the basement concrete slab
2| Remove the concrete pieces and debris out of the basement
3| So, dig a hole under the stone footing.
4| Drill from beneath the stone foundation.
5| Install rebar in the holes. This will attach the old stone foundation of the new one.
6| Pour a new concrete footing with the same width as the old stone footing.
7| Install rebar on the side where you will supposed to dig the next hole. This will link one piece of the new concrete foundation of another new one.
8| Allow time to the concrete to harden.
9| Dig the next hole and pour the concrete footing.
10| Proceed in the same way until the entire stone foundation is underpinned.
11| Dig out in depth the rest of the floor.
12| Pour the new concrete slab.