Dig Out a Basement in an Existing House
Wouldn't it be great to find a great big closet in your house? That way, you could store more stuff and not have to make the decision to give it away or throw it out. If you have a partial basement with some headroom, it's just like having that closet. You need to have access through an outside door or a stairway from the main floor. Homes that are built into hills often have this configuration. Part of the basement has standing room on a dirt floor, and part of it is sloped, going up the hill. Additionally, some older homes originally had stone foundations. If/When these were replaced with block or concrete, the old stone walls were kicked into the house.
Contents
Steps
- Before you begin, talk to your local pest control folks. If you live in termite heaven [generally: south of 40 degrees North latitude], they may advise you to treat the ground before building
Remove Problematic Dirt
- Find out what can be removed. Generally, footing should not be disturbed in an area that is 45 degrees from its base, as shown in the drawing. See warnings.
- If you have an outside door, this will simply be a matter of carrying the dirt outside with a wheelbarrow. However, if your entry involves stairs, you may want to hire some teenagers to bucket it out while you dig.
- Remove the dirt in the area shown in the drawing between the existing grade and the red lines. Try to keep the new floor flat and level. It should be about four inches below the footing on the existing headroom side.
The Floor
- Place 4x4" pressure-treated posts on the ground along the length of the room, approximately {{safesubst:#invoke:convert|convert}} apart. See call out 1. They should be about level with the bottom of the studs on the front wall. These posts just "float" on the ground and are the footings for the new floor.
- As soon as they are stable and in place, cover the entire area with 4 mil or 6 mil thick polyethylene sheet material.
- Bring the sheet of 'poly' up to the footings, make slits in it and lead it up the hill beyond the footings about {{safesubst:#invoke:convert|convert}}.
- Overlap the slits and weight them with rocks or bricks. Bring the edges on the other 3 sides up the walls about one foot.
- Trim the excess flash off later. This is for mold prevention. Leave this step out and everything stored in your new closet will have a nasty smell in no time! [Unless you live in the Sahara or Atacama desert!]]
- To install the joists,Place the pressure-treated 2x6" floor joists from the bottom of the studs on the front wall across the 4"x4" posts to the far 45 degree slope. See call out 2.
- To finish the floor, nail the joists to the posts at 16" or 24" intervals and cover with plywood.
Constructing the Far Wall
- Construct the short wall along the length of the room with 2x4" studs, and tie it to the far wall with 2x4s acting as joists for a long shelf.
- Cover the wall and shelf with plywood for a finished look.
Tips
- If your basement is damp, find and repair the problem before taking on this project.
- Your basement may not look just like this one, so you will have to modify this plan for your own.
Warnings
- Your local authority may require you to take out a building permit for this type of work. Check with your local Building Department if you are not sure.
- This is not a living area and should be used only for storage.
- This plan is general and may or may not comply with local building codes.
