Crawlspace excavation is a long and complicated process. Here are some steps and procedures we follow to get the job done right and turn your small, musty crawlspace into a basement with purpose.
We first locate a space on the exterior wall of your crawl space where you can safely enter the basement. This will be with a temporary or permanent set of steps. The opening in the wall should be large enough to accommodate at least a 36-inch door. Preferably we make the area for the steps at least 4 feet wide.
NOTE: If your soil is sandy or rich with gravel and or may be full of water at least part of the year do not consider this procedure. It is very dangerous and you may damage or lose your house.
Before we excavate for your outside exit, a header is built of sufficient size to hold the floor of the home in place while removing the old foundation.
You must excavate to a depth that will accommodate a 4-inch concrete slab and still have at least 7 1/2 feet of clearance under your floor joist. It is entirely possible that you will have 48 inches of soil to remove. The deeper you go the more hazardous the work, this point is important and cannot be stressed often enough.
We remove the soil just sufficiently to work along the wall without altering the entire area around what you wish to change. Once the soil is removed to the depth you wish, we pour a 8-inch by 16-inch footer.
The footer should be below the bottom of the new slab so it is essential to dig the area for the footer below the level removed for the floor.
When the block is level with the bottom of the old foundation wall, we pour a 4-inch thick concrete slab on top of the wall and connecting to the outside existing wall.
Before pouring the cap, you must fill the area between the block and the soil that is under the old foundation with fill sand or “Pea-gravel.” Assuming that there is support under the center section of the floor system, you will have to provide extra support for the beam that is present while excavating. A steel post at the footer will hold the floor of your new space and provide this support. The footer for this should be 8 inches thick and 24 inches square.
We then level the floor area for your new slab and install 4 inches of perforated plastic pipe draining into a sub pit with an automatic sub-pump that dispenses the water outside the home (5 to 10 feet away from the foundation). We use “Pea-gravel” as filling under the slab but you can use fill sand as an alternative.
You can build the stairwell to the outside in a similar fashion but you need to cover it with a steel “pre-fab” unit such as a “BILCO”. They have provisions for locking and if you take care of them, they will last for years.
Basement Solutions offers free estimates at your home with no obligations. For those who want a crawl space excavation in Pennsylvania, New Jersey and parts of Delaware – Please call our office at 610-495-9111 to set up an appointment! If you are reading this off-site you can contact us at our website, www.basements911.com.
We look forward to turning your old, moldy and musty crawlspace into the basement you’ve always wanted!
Check out our video of the full process start to finish.