How much does it cost to put a underground room lower than a house measure 25' x 30' within minnesota? ...
Answers: Usually basements are dug before the house is built. "Putting" one immediately could cause the house to collapse.
The 1st step is hire a well brought-up local engineer to look at the home and draw plans for the project. He will permit you know whether the project is feasible or not.
If it is, filch the plans to several reputable local contractors who are licensed to do the work and get bids.
Their bids will report to you the answer to your question.
you could be looking at 20,000 - 25,000...sour the top of my head...