Excavate Crawlspace?

Suppose you had a house with a partial basement and an adjacent crawlspace under the rest of the house. Would it be possible to excavate part of the crawlspace to enlarge the basement?

I realize that hauling all of the dirt up and out of the basement would be a big job.

 

Yes, it is possible. You did not say how large your crawl is.

 

I'm not sure how large the crawlspace is because it's in a house that I've only visited once. I'm thinking about buying the house, but I'd like to have more basement space.

I'd estimate the size of the crawlspace as about 10 feet wide by 15 feet deep. What I have in mind is just a partial excavation to create a closet-sized area, possibly 6 feet wide by 8 feet deep.

 

Just to clarify my previous message:

When I wrote "deep", I meant the front to back dimension, not the top to bottom dimension. The partial basement has a "normal" ceiling height (seven and a half feet?) and the crawlspace has a height of about three feet.

 

Matt,
I also have a partial basement and I'm currently excavating the crawlspace side (18' X 20' 3 feet deep) all the way to the existing foundation walls. I work with a structural engineer and he has told me as long as a footing exists under the foundation wall (old houses sometimes don't have them) I can dig out right up to the wall. My house is a 80 year old Row home in Baltimore with brick walls. So you should be fine if all you want to do. You could probable dig out all the way to the walls. But get a permit and consult with a structural engineer if you plan on doing this yourself.
You are right about it being a big job. I'm digging mine out myself using sand bags ($1. at army/nave surplus stores) and my pick up truck and the local landfill. I fill the bags and hand them out the basement window to my friend who loads them on my truck.
A neighbor dug his out a few years ago,all the contractors wanted around $5000. just for dirt removal! A lot of man hours involved.
Hope this helps you out.

 

This_dong,

Thanks for sharing your experience.

Do you have an estimate of how many cubic feet of dirt you can dig out per hour?

 

About 30 cubic feet/hour. (approx. 1000 lbs. of dirt)

 

I think any estimate of cubic feet per hour should be used carefully. The rate for heavy rocky clay would be very very different than the rate for sandy soil, perhaps by a 100 to one ratio.

 

That's a good point about how variations in the local soil would effect the rate of excavation.

My next question: Once you've cleared out the dirt, you'll just have a dirt "floor", right? So then I assume you'd need to pour concrete for a floor slab.

 

I havn't got to that stage yet and don't know everything about it. What I do know is you should dig down 6-8" inches below the hieght you want the finished floor to be. This allows room for layers of gravel,rebar,sand,a vapor barrior and the concrete You also need to level the floor really well. I've heard this isn't that hard with the help of leveling instruments/equipment. Also you need to find out about expansion joints that have to be placed between the floor and the walls. It seems the floor can expand at a different rate than the walls and you can cause major damage to the foundation wall. Maybe Jack the contractor can give you some help with this part of it. Also, if you don't have much experience mixing concret, I heard you shouldn't try to mix the concrete yourself. The pro's can give you the correct ratios of sand,water and cement. I plan to have the local concrete co. pour it through the basement window after I get everything set up inside. But this is still about month away.