ServiCover📌 Key Takeaway: Converting existing space ($50-$150 per sq ft) is usually the cheapest way to gain living area. Bump-outs suit small gains; full additions add whole rooms.
Options Compared
| Option | Per Sq Ft | Space Gained | Disruption |
|---|---|---|---|
| Basement conversion | $50-$100 | Large | Low |
| Attic conversion | $50-$150 | Medium | Low-medium |
| Bump-out | $85-$200 | Small | Medium |
| Ground-floor addition | $125-$250 | Large | Medium-high |
| Second story | $200-$500+ | Large | High |
Questions to Ask First
- Do zoning setbacks allow building out?
- Can your foundation support a second story?
- Does the attic have enough headroom?
- Does the basement stay dry?
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Get Free Quotes →Frequently Asked Questions
Can I live at home during a second-story addition?
Often not for part of the project, since the roof may be removed.
Do bump-outs need a foundation?
Some are cantilevered; others need footings. Your contractor will advise.
🔎 How we research: The ServiCover Editorial Team compiles prices and guidance from published 2026 cost guides, manufacturer information and industry sources. Prices are national ranges and vary by location, home and provider, so always compare written quotes. We don't perform the work ourselves, and we may earn a commission when you request quotes through our partners — see our Advertiser Disclosure.