My basement is 1,100 square feet fully above ground unfinished. The foundation is not level varying 5’6 to 6’11. We plan to dig the shallow sections (3/4 of the total space) so that it is all the same depth. Just wondering if we should we just dig a little more to 8’ or is 6’11 good enough?
We considered raising the house but the cost to raise was considerably higher than the initial costs to dig. Its really hard to compare since its two totally different things.
I am not sure what is the building codes in your area but in New York, if you are willing to use a basement as a living space, the ceiling has to be 8’ high.
In Colorado there is a 7 foot minimum head height requirement and 8 foot ceilings are recommended.
Keep in mind that if you are digging out your basement for height, you might wind up going deeper than the foundation itself. In other words, once you’ve dug out a portion of the floor, you might step back and see the stone foundation, then under the foundation there’s nothing but dirt. This situation is extremely DANGEROUS and requires underpinning the foundation. This is not to be done by someone with no experience, such as the homeowner.
Underpinning is when a series of ‘plugs’ or 4-8’ runs of concrete will need to be poured under the foundation. It’s tedious work, but if you don’t do it, your entire home could collapse, since there’s nothing supporting the dirt wall UNDER the foundation.
Urban Remodelers is correct, digging down can be very risky if not performed correctly. For a project like this, it would be wise to consult a structural engineer to ensure that the foundation system is properly reinforced and installed.
Given the effort to properly reinforce the existing foundation system for digging down, the cost difference between going down 6" and going down 2’ is not significant. It would probably be the best value to go down to give a head height of 8’.
An onsite visit with need to be done in order to estimate this.
