Basement Guide
How Much Does It Cost to Finish a Basement?
By Dioclecio Gomes, Founder & Owner3 min readUpdated October 2, 2026
In This Guide
In Massachusetts, finishing a basement typically runs $30 to $75 per square foot, so a 700 square foot basement often lands between $21,000 and $52,000. National guides report lower figures: This Old House gives $7,000 to $23,000 for 1,000 square feet and Bob Vila gives a national average of $18,398. The gap is mostly scope, since plumbing, a bathroom, an egress window and waterproofing each add thousands.
Finishing a basement costs more or less depending on what is already in place and what you add. National figures come from This Old House and Bob Vila, and our own pricing from the basement remodeling page.
How Much Does It Cost to Finish a Basement?
Our Massachusetts range is $30 to $75 per square foot, depending on scope. This Old House reports $7 to $23 per square foot nationally, or $7,000 to $23,000 for a 1,000 square foot space. Bob Vila reports a national average of $18,398, within a range of $2,800 to $34,500. Our range is higher because it prices a full-scope finish, and we quote it in writing after measuring.
| Size | Mr. Gomes range |
|---|---|
| 700 sq ft | $21,000 to $52,000 |
| Per square foot | $30 to $75 |
What Add-Ons Raise the Cost?
This Old House lists waterproofing at $1,900 to $6,500, egress windows at $2,500 to $5,300, a ceiling at $1,600 to $3,600, electrical work at $1,300 to $12,000, plumbing at $2,500 to $15,000 and HVAC at $2,000 to $11,000. Bob Vila gives a bathroom at $8,000 to $15,000 and permits averaging $1,350. Each is a range because it depends on what the space already has.
Do You Need an Egress Window?
If the basement will include a bedroom, yes. Bob Vila, citing the International Residential Code, says basements with one or more sleeping rooms need an emergency egress opening in each sleeping room, and lists the minimums: 20 inches wide, 24 inches high, 5.7 square feet of net clear opening and a sill no higher than 44 inches. A window well needs 9 square feet of floor space, at least 36 inches in each direction, and a permanent ladder or steps if it is deeper than 44 inches. Confirm the rules for your town with your building department, and see our permit guide.
Thinking about finishing your basement?
We check moisture, ceiling height and egress, then give you a written price after a free in-home visit.
Get a Free Basement EstimateWhat Should You Fix Before Finishing?
Moisture comes first. Bob Vila lists waterproofing at roughly $4,500 on average, and This Old House at $1,900 to $6,500, which is far cheaper than finishing over a damp wall and then tearing it out. We look for dampness, efflorescence and drainage problems during the in-home visit.
Does a Finished Basement Add Value?
Bob Vila says a finished basement can return up to 70 percent of its cost at resale. Beyond resale, it adds living space without changing the footprint of the house.
The Bottom Line
Plan on $30 to $75 per square foot in Massachusetts, which puts a 700 square foot basement at roughly $21,000 to $52,000. Moisture, egress and a bathroom are the biggest swing factors. Get a Free Basement Estimate
FAQ
How much does it cost to finish a 1,000 square foot basement?
This Old House gives $7,000 to $23,000 nationally. At our Massachusetts range of $30 to $75 per square foot, 1,000 square feet would be roughly $30,000 to $75,000, depending on scope.
Do you need a permit to finish a basement?
Often, especially when adding plumbing, electrical or HVAC. Bob Vila gives permits an average of $1,350. Confirm with your local building department.
Can you have a bedroom in a finished basement?
Yes, with an egress opening in the bedroom. Bob Vila, citing the International Residential Code, says each basement sleeping room needs an emergency escape and rescue opening, so plan the window before the layout.