One guy on a Bobcat would have that dug out after lunch if he's got the space to dig and maneuver.

Yes..."crazy expensive" comes into play. Depending on where you live, the "jacking" of a house starts at $10K - $30K. Then you have the REST of the work to pay for.

Excavation is just the start...couple of K just for that. Then the pouring of the slab is normally double that of a new build (tight spaces make it slow; time is money so slow = expensive).

And all this while you live ELSEWHERE. Remember to budget in RENTAL costs for your relocation during the time the house is "jacked". Once it is put down on to the foundation (it has to cure....so it can take several weeks before the house gets put down on to the foundation) you can move back in - assuming plumbing and electrical are ready to roll.

And once you have everything opened up like that, you have to upgrade electrical and plumbing to current code requirements. That will add even more costs. A house this old will HAVE TO ASSUME you have asbestos/lead somewhere. I would assume a FULL HOME asbestos mitigation is required. That adds another $$$K onto the renovation.

I would ensure you have access to $150K - $250K before you start looking for contractors. Get your bank to pre-approve your financing. Make sure you can reach the UPPER range of costs before you start. You have to be able to fix everything that they "find" (think: Pandora's Box) once they open everything up (that's why you have to ASSUME full asbestos remediation...and build in that type of HEAVY costs into your budget).

There is nothing worse than getting in over your head and having to file for bankruptcy because the project got out of hand and you ran out of financing. A home this age, with a project such as this is BEGGING to become a "money pit".

Find out your UPPER range for financing. Then find out if it is better to leave it alone, move, or go ahead with the project.

Good luck. This is a MAJOR project that requires MAJOR planning and HIGH END professionals who have done this multiple times before.

Thank you! The crawlspace is dirt floor and it it at least 4 feet high. The under deck area would be accessed from an interior stairs- we would cut a hole in the current exterior foundation to connect the two spaces. There is also a poured concrete porch in front of the house that the roof spans to, so some of the weight of the house is on the porch which would remain in place. most guys we've talked to have said jacking up the house isn't necessary, but we haven't discussed the basement/deck addition option with them.

We have already done the asbestos and lead remediation, and fortunately don't have to live there for another year, but this decision has us severely waylaid.

If you're considering this as a DIY project, a pro would be the safer option -- they'll be more likely to have all the appropriate equipment and would be more likely to know local building codes.

The slope of your lot and how the water on your lot drains matters a great deal. Your basement will need to be waterproofed and have an exit to the outside.

Curious to know if you completed the project. As well as any tips for digging under an existing porch/deck and building a finished room.

We dug out part of our basement to have some full height storage and a bulkhead for access. It was a huge money suck, took forever and cost way more than estimated. There is a lot more to it than you think. None of the aspects are easy, not digging, not supporting, not waterproofing, not fireproofing, not ceiling. Nothing. Figure out some other way to get the space you want.