During the Great Depression, excavating crawlspaces was a popular activity. At that time, there were few distractions such as television or even employment that allowed homeowners to add equity to their home or to add an income-generating apartment. Excavating a crawlspace is a labor-intensive job, but the gain is worthwhile.
Lessons Learned When Excavating a Crawlspace
A lot of the additions were fairly well planned and implemented. To dig below an existing foundation can be dangerous if not completed correctly. Many people completing an excavation had the insight to not dig too close to the exterior walls.
When they set out to excavate crawlspaces, they would remove the fill to a few feet of the foundation then lay new concrete retaining walls to help support the original foundation. In the finished product, these retaining walls would create a bench or shelf that created good usable storage or benches.
Unfortunately, there were others that did not incorporate these basic philosophies when excavating crawlspaces. Lessons learned during this time period included the critical failure of a foundation that would result in a home falling in on itself. Other results of an improperly implemented addition are sagging walls, doors that will not shut properly, non-level floors, and a myriad of other issues.
Proper Excavating to Avoid Disaster
The main issue that went unrecognized was that one should never disturb the soil under a load-bearing wall. Engineers talk about a safe angle of repose when you need to slope the fill from the bottom of the foundation. This will calculate how quickly you can slope the fill from the foundation. It is based on the load on the foundation, the soil composition as well as other criteria. This is best left to a professional to plan.
A better, safer and unfortunately more expensive, way to add a basement from excavating a crawlspace would be to hire a home moving or leveling contractor to jack the home up on house jacks.
This process involves raising the home on steel beams and supporting it with cribbing- usually wooden planks. While adding to the budget, this process will allow you to do a better job as well as keeping you and your home safe.
Older homes can stand to have their existing foundations inspected. Back when a lot of these older homes were built, builders did not have access to the materials and technology we have today. They did not use high grade cement, use rebar to strengthen the concrete and water-proof coatings, for example.
There will also be settling that needs to be addressed. Also, do not forget to include proper drainage for your new foundation. This will alleviate moisture problems in your new excavated crawlspace. Consider installing a vapor barrier as well.
If you are considering continuing with your excavation of the crawlspace, you can take this time to include some value added steps. Adding earthquake protection is something that should be considered. No matter where you live, there are at least four to five earthquakes annually.
The vast majority are so minor that they barely show on seismographs, but there is always the chance of a “big one” in any area. Other improvements should include plumbing and electrical fitting for your new space as well as considering ceiling height and radon mitigation.
When done properly, excavating crawlspaces can add up to fifty percent more living space and make your home safer. This is not a bad gain for a few months of digging and a little planning. You don’t even have to wait for the next stock market crash or the Great American Dust Bowl to return.