Room addition cost in Massachusetts
A room addition of about 14 x 18 ft in Massachusetts usually costs about $50,200 to $87,500 with standard materials when you hire it out. If you do the work yourself and hire only the licensed trades, it is about $25,900 to $48,600. The tables below show three sizes at three material levels. They include the foundation, frame, roof, windows and doors, the finish, plans and permits, a dumpster, delivery, sales tax and a 15% cushion for surprises.
Price my own room additionCost by size and materials
Each box shows a low, a likely and a high price for the whole job. "Hired out" means pros do everything. "Do it yourself" means you do the jobs that are fine to do yourself and still pay for the licensed trades.
| Hired out | Do it yourself |
|---|---|
| Budget materials Cheapest that's still decent | |
| Low $35,800Likely $49,100High $62,300 | Low $18,000Likely $26,000High $34,000 |
| Standard materials Off the shelf at Home Depot or Lowe's | |
| Low $39,900Likely $55,000High $70,200 | Low $21,600Likely $31,000High $40,500 |
| Premium materials Specialty stores, custom pieces | |
| Low $50,800Likely $70,900High $91,000 | Low $31,100Likely $44,600High $58,100 |
| Hired out | Do it yourself |
|---|---|
| Budget materials Cheapest that's still decent | |
| Low $44,800Likely $61,000High $77,200 | Low $21,200Likely $30,500High $39,900 |
| Standard materials Off the shelf at Home Depot or Lowe's | |
| Low $50,200Likely $68,800High $87,500 | Low $25,900Likely $37,300High $48,600 |
| Premium materials Specialty stores, custom pieces | |
| Low $64,600Likely $89,800High $115,000 | Low $38,600Likely $55,200High $71,700 |
| Hired out | Do it yourself |
|---|---|
| Budget materials Cheapest that's still decent | |
| Low $59,100Likely $80,200High $101,300 | Low $26,800Likely $38,500High $50,200 |
| Standard materials Off the shelf at Home Depot or Lowe's | |
| Low $66,600Likely $91,000High $115,500 | Low $33,400Likely $47,800High $62,100 |
| Premium materials Specialty stores, custom pieces | |
| Low $86,600Likely $120,000High $153,400 | Low $50,900Likely $72,500High $94,100 |
What is included
For the medium size.
- Foundation: excavation and backfill; footing: concrete and rebar; foundation wall: concrete; foundation wall: forming and pouring.
- Frame, roof and siding: floor framing: main level; wall framing: main level; roof: rafters, sheathing, underlayment, shingles, drip edge; siding: main level.
- Windows, doors and openings: windows: main level; opening cut into the house wall (header, posts, patching).
- Main level: Finished room (family room, office, finished lower level): insulation; drywall, mud and paint; trim, doors and paint; flooring; electrical: outlets, lights, wiring; mini-split heat pump, installed.
- Site, plans and permits: plot plan.
What we assumed
- A ranch house with the addition joined to it, one level, with a shed roof
- Town sewer, a flat lot, no ledge, and a concrete truck can reach the spot
- Built in spring, with a 200 amp electrical panel
- No wetlands nearby, and the new wall is well clear of the property line
Things that can add cost
These are not in the tables above. The estimator asks about your house and lot and adds the ones that apply.
- Ledge or boulder removal: $3,000 to $20,000.
- Possible septic upgrade: $15,000 to $45,000.
- Possible sewer fee per added bedroom (each): $500 to $4,200.
- Concrete pump truck (each pour): $600 to $1,200.
- Conservation Commission filing: $300 to $2,500.
- Engineer-stamped plans: $1,500 to $4,000.
See the other cost guides, the privacy page and the terms.