Know what your home addition should cost
Most projects run $65,600 – $98,400. Answer six quick questions for an itemised range tuned to your ZIP code — the whole number, up front, before we ask for anything.
What home addition work costs in 2026
| Project | Typical range |
|---|---|
| Ground-floor room Bedroom, family room or office on a new slab or crawl space | $65,600 – $98,400 |
| Bump-out Small extension off an existing room, under about 150 sq ft | $55,800 – $83,600 |
| Second-storey addition Structural engineering and a temporary roof tear-off | $101,700 – $152,500 |
| Kitchen or bathroom addition New plumbing and electrical runs drive the cost | $114,800 – $172,200 |
| Garage conversion Existing structure — insulation, flooring and HVAC | $29,500 – $44,300 |
Where the money goes
Foundation and site work
$11,500 · 14% of the job
Framing and structure
$16,400 · 20% of the job
Roofing, siding and windows
$13,100 · 16% of the job
Electrical, plumbing and HVAC
$14,800 · 18% of the job
Insulation, drywall and paint
$11,500 · 14% of the job
Flooring, trim and fixtures
$9,000 · 11% of the job
Permits, design and inspections
$5,750 · 7% of the job
Questions homeowners ask
How much would a 20x20 addition cost?
A 20x20 addition is 400 square feet. At mid-range finishes on a ground-floor slab, expect roughly $66,000 to $98,000. Budget finishes bring that down toward $46,000; premium work pushes past $150,000.
What is the average cost of a 12x24 addition?
A 12x24 addition is 288 square feet — around $47,000 to $71,000 at mid-range finishes on a ground floor. A second-storey addition of the same size runs about 55% more because of the structural engineering and the temporary roof tear-off.
How much does it cost to add 2000 square feet to a house?
At 2,000 square feet you are building most of a house. Mid-range ground-floor work lands around $330,000 to $490,000. At that scale the foundation, roof tie-in and utility capacity often need upgrading, so get a structural engineer involved before budgeting.
What drives the cost of an addition most?
Plumbing. A bedroom or family room addition is the cheapest per square foot; adding a kitchen or bathroom runs roughly 75% more, because new supply and waste lines have to reach the addition.