How Much Does a Bump-Out Addition Cost?
On February 25, 2026 By newsroom Topic: Home Services
What is a Bump-Out?
- A bump-out is a small extension of an existing room (e.g., kitchen, bedroom) without the cost or scale of a full room addition.
- Sizes: Typically extend 2–15 feet from the home, with smaller ones often cantilevered without a foundation.
Cost
- Average Cost Range: $4,000–$30,000.
- National Averages:
- Small cantilevered bump-out (2 feet): $5,000.
- Larger bump-out (4x10 feet): Up to $30,000.
- Regional Variations:
- Boston, MA: $6,000–$35,000.
- Detroit, MI: $3,500–$30,000.
- Phoenix, AZ: $5,000–$28,000.
Cost Breakdown
- Permits: $400–$1,500.
- Contractor Fees: 10%–20% of the total project cost.
- Windows: $3,500–$15,000 (large bay windows or skylights at higher end).
- Electricity: $50–$100/hour for wiring or installing fixtures.
- Interior Finishing:
- Painting: $2–$6/sq ft.
- Flooring: $3–$22/sq ft.
- Exterior Finishing:
- Siding: $3–$11/sq ft.
- Roof extension: $50–$85/linear foot.
- Plumbing (if needed): $45–$200/hour or $1,500–$6,100 for fixtures.
- Foundation (if required): $4–$16/sq ft.
Cost by Room Type
- Kitchen Bump-Out: $100–$300/sq ft (plumbing and electrical increase costs).
- Bathroom Bump-Out: $200–$300/sq ft (more costly due to plumbing).
- Bedroom Bump-Out: $80–$200/sq ft (lower range without plumbing).
- Garage Bump-Out: $40–$70/sq ft (simpler construction).
How Far Can a Bump-Out Extend?
- Cantilevered Bump-Outs: Up to 2 feet without additional support.
- Larger Additions: Require foundation or posts for structural support.
How to Save on Costs
- Limit Mechanical Work: Avoid extensive plumbing or HVAC changes.
- DIY Small Tasks: Take on demolition, debris removal, or painting.
- Compare Quotes: Get at least three bids, avoiding unusually low estimates.
- Reuse Materials: Use salvaged or second-hand materials when possible.
Budget-Friendly Options
- $5,000 Budget: A 2-foot kitchen extension or bay window addition.
- $10,000 Budget: 2x10-foot library nook or playroom storage.
- $20,000 Budget: 3x10-foot entryway or porch expansion.
- $30,000+ Budget: 4x10-foot laundry or mudroom addition.
