Updated September 2026
What does a dormer cost in NJ?
Use the calculator for a planning range based on 2026 pricing in Union County and nearby towns. Then get a real price after a free site visit.
Typical price ranges
| Project | Typical range | What drives it |
|---|---|---|
| Gable (doghouse) dormer | $15,000–$30,000 each | Size, window, interior finish |
| Shed dormer, shell only | $45,000–$80,000 | Width, roofing, siding, windows |
| Shed dormer, finished with bath | $95,000–$160,000 | Rooms, bath, finishes, HVAC |
| Attic conversion, no dormer | $30,000–$60,000 | Headroom, stairs, insulation |
| Upstairs full bathroom | $25,000–$40,000 | Distance to existing plumbing |
| Full second story on a Cape | $200,000–$350,000+ | Size, structure, finishes |
What moves the price
- Width. A dormer across the full back of the house costs more but adds the most space.
- Bathroom. Locating it over existing plumbing saves thousands.
- Stairs. Steep, narrow Cape stairs sometimes need rebuilding to code.
- Heating and cooling. Ductless mini-splits are often the most efficient option upstairs.
- Roof condition. If the rest of the roof is old, re-roofing everything at once gives a matching, warrantied roof.
- Zoning. A variance adds design and hearing costs.
These are planning ranges for our service area, not quotes. Every home is different. Your written price comes after a free in-home visit.
Want a real number?
A 45-minute visit gets you a written scope and a firm price. No obligation.