Attic Guide
Attic Renovation Cost: What It Takes to Finish or Convert an Attic
By Dioclecio Gomes, Founder & Owner4 min readUpdated October 19, 2026
In This Guide
Block Renovation's 2026 guide puts most attic renovations at $10,000 to $50,000, with a national average around $20,000 to $25,000. By scope, a basic finish runs $30 to $60 per square foot, a mid-range living space $60 to $100, and a full conversion $100 to $150 or more. Dormers ($8,000 to $30,000), a code-compliant staircase ($3,000 to $10,000) and a bathroom push the total up.
Attic renovation cost depends less on the size of the attic than on what it takes to make it a legal room: framing, headroom, a staircase and an escape window. All prices below come from Block Renovation's July 2026 guide and are national figures. Code rules come from municipal IRC handouts. Ready to price your own attic? See our attic remodeling page.
How Much Does It Cost to Renovate an Attic?
Block Renovation puts the typical total at $10,000 to $50,000 and the national average around $20,000 to $25,000. By attic size:
| Attic size | Typical cost |
|---|---|
| Small | $10,000 to $20,000 |
| Medium | $20,000 to $35,000 |
| Large | $35,000 to $50,000 or more |
What Does an Attic Conversion Cost per Square Foot?
| Scope | Cost per square foot |
|---|---|
| Basic finish (insulation, drywall, flooring) | $30 to $60 |
| Mid-range living space | $60 to $100 |
| Full conversion | $100 to $150 or more |
At $50 per square foot, Block's example puts a 400 square foot attic around $20,000.
What Does It Cost by Room Type?
| Project | Typical cost |
|---|---|
| Storage space | $5,000 to $20,000 |
| Home office or bonus room | $10,000 to $30,000 |
| Bedroom | $8,000 to $30,000 |
| Bathroom addition | $9,500 to $50,000 |
| Full living space or suite | $20,000 to $80,000 or more |
What Do Dormers, Stairs and Other Items Cost?
| Item | Typical cost |
|---|---|
| Dormer | $8,000 to $30,000 |
| Code-compliant staircase | $3,000 to $10,000 |
| Egress window, installed | $2,500 to $6,000 |
| Skylight | $1,000 to $3,500 each |
| Spray foam insulation | $3 to $5 per square foot |
| Insulation, whole attic | $1,500 to $6,000 |
| Drywall | $1,000 to $3,500 |
| Flooring | $1,500 to $6,000 |
| Structural engineering | $500 to $3,000 |
| Electrical panel upgrade | $1,500 to $3,000 |
| Permits | $500 to $2,000 |
| Asbestos abatement, if found | $2,000 to $8,000 |
Want a real number for your attic?
We look at the framing, headroom and stair location, then give you a written price after a free in-home visit.
Get a Free Attic EstimateWhat Do Real Attic Budgets Look Like?
Block Renovation walks through three sample projects:
- Home office, 350 sq ft: $18,400. Permits, demolition, electrical, spray foam, drywall, a mini-split, flooring, paint, trim and doors.
- Bedroom, 550 sq ft: $43,900. Adds engineering and joist work ($4,600), a staircase ($7,500) and an egress window ($3,900).
- Primary suite with bath, 700 sq ft: $78,000. Adds a shed dormer ($12,000), bath plumbing ($3,600) and bath fixtures, tile and waterproofing ($8,900).
The jump from office to bedroom is mostly the stair, the structure and the escape window, which is why those items deserve attention before anything else.
Which Code Items Drive the Cost?
Headroom. The model code that Massachusetts' residential code is based on sets the bar. As the City of Boise IRC handout quotes section R305.1, habitable space needs a ceiling height of at least 7 feet. For rooms with sloped ceilings, the required floor area must have at least 5 feet of height, and at least 50 percent of that required floor area must have at least 7 feet. If too little of the floor clears 7 feet, the fix is a dormer, and that is often the largest single line.
Escape window. The Jersey County IRC R310 handout lists the rules for every sleeping room's emergency escape opening: a net clear opening of at least 5.7 square feet, at least 24 inches high and 20 inches wide, with the sill no more than 44 inches above the floor, and it must open from inside without keys or tools. The handout also points out that the minimum width times the minimum height does not reach 5.7 square feet, so a real window has to be larger than both minimums.
Framing. Block Renovation notes that engineered trusses generally cannot be cut or modified, so truss attics rarely become living space at a reasonable cost.
Massachusetts adopts the model code with its own amendments, so the details are confirmed with your town's building department. Our permit guide covers which projects need one.
The Bottom Line
Use the ranges above to set a budget, then get a price for your own attic: the framing, the height and the stair location matter more than the square footage. We give a written price after a free in-home visit. See our attic remodeling page or call (508) 304-3447.
Get a Free Attic EstimateFAQ
How much does it cost to finish an attic?
Block Renovation puts most attic renovations at $10,000 to $50,000, with a national average around $20,000 to $25,000, and a basic finish at $30 to $60 per square foot.
How much does it cost to turn an attic into a bedroom?
Block Renovation lists $8,000 to $30,000 for a bedroom, and its 550 square foot sample bedroom with engineering, a staircase and an egress window came to $43,900.
How much does an attic dormer cost?
Block Renovation puts a dormer at $8,000 to $30,000. It is often needed to get enough 7 foot headroom.
Is finishing an attic cheaper than an addition?
Usually, because the roof and foundation already exist. Our published range for a single-room, ground-floor addition in Massachusetts is $35,000 to $70,000.
Do I need a permit to finish an attic?
Yes. Turning an attic into habitable space changes structure, wiring and often plumbing, so it needs a building permit. Block Renovation puts permits at $500 to $2,000.