How To Dig Out A Basement In An Existing Building

When you decide to add extra space to your home, there are only three options: out, up or down. To choose which option is the best for you, there are many things that need to be considered, from design and functionality to costs. The basement under an existing building is a perfect solution for adding extra space to your house. However there are certain factors to consider like stability and safety precautions, an access through an outside door or a stairway from the main floor, etc. Below you can read about the right way how to dig a basement in an existing building and provide an extra space in your home.


Check With A Local Pest Control – Before you begin with works, check with your local pest control for construction permit. Depending on where you live, the local pest control may advise you to treat the ground before building in order to avoid exposure to termites.

Foundation Issues – The first step before you begin digging is evaluating the condition of the foundation. If your house is old, the foundation may be in bad condition and may need to be redone. In this case, the best you can do is to contact someone with experience to construct a new proper basement foundation. The geology under your home is also important. For instance, if your home is located on semi-solid or solid rock, digging a basement under your home will not be worth. But, if you have a gravel or soil base which allows work with a skid steer loader or other similar digging machine, then this project can be executed.

Level The Ground In The Basement – You will need to remove the dirt and get it out of the basement. Have in mind not to dig where the slope is 45 degrees from the base of the sidewalls, otherwise the basement walls may collapse. You will need a skid steer loader to remove the dirt if there is enough space to fit a skid steer loader in your basement. This compact, functional and versatile construction machine can do the job in no time and with little effort. If you are not willing to spend a lot money on a new skid steer loader, you can rent one or buy a used skid steer loader.

Prepare The New Floor – First, place 4×4 pressure-treated posts on the ground along the room. Once stable in the place, cover the entire room with 4-6 mil thick polyethylene sheet material. Then, overlap the slits and weight them with rocks. For mold prevention, trim the excess flash off. At the end, hide the polyethylene material with 2×6 floor joists to create the basement floor.

Prepare The Basement Walls – The last step is to prepare the basement walls using 2×4 studs. You can also tie the short wall to the far wall with additional 2×4 studs acting as joists to create a shelf. Cover all the walls with plywood and paint them with the color you like.

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