How much does a second-story addition cost?
A second-story addition often costs $200 - $500 per square foot. A partial second story commonly lands around $100,000 - $250,000, while a full second floor can reach $200,000 - $750,000+ depending on size, structure, finishes, and utilities.
Second-story work is expensive because it is not just new rooms. The project can involve engineering, temporary roof removal, stairs, framing, structural reinforcement, HVAC, electrical, plumbing, siding, windows, insulation, permits, and temporary relocation.
Second-story addition cost by scope
Partial second-story addition
$100,000 - $250,000+How to tellNew bedroom, office, bath, or suite over part of the home
The fixPrice structural review, roof tie-in, stairs, utilities, and exterior matching
Full second floor
$200,000 - $750,000+How to tellThe project adds a full new level over most or all of the existing footprint
The fixExpect a major design, engineering, permitting, framing, and relocation plan
Second story over garage
$60,000 - $200,000+How to tellYou want a bedroom, office, studio, or suite above an attached garage
The fixCheck garage foundation, fire separation, stairs, insulation, HVAC, and egress
Structure and foundation upgrades
$5,000 - $50,000+How to tellExisting framing, beams, posts, or foundation may not support new loads
The fixGet structural engineering before assuming the house can simply be built upward
Utilities, bathrooms, and finish level
Often 10% - 30%+ of budgetHow to tellNew bathrooms, laundry, HVAC zones, custom windows, premium siding, or high-end finishes are included
The fixSeparate shell costs from finish allowances before comparing bids
Before pricing a second story
- Check zoning height limits, setbacks, lot coverage, parking rules, historic restrictions, and HOA rules before design goes far.
- Ask whether an architect, structural engineer, survey, and permit drawings are included in preconstruction.
- Decide whether you can live in the house during construction. Roof removal, utility shutdowns, and stair work can make that unrealistic.
- Ask builders to separate design/engineering, shell, utilities, finishes, permits, temporary protection, and contingency.
Unlock the hiring checklist
Use this before you call an addition contractor, so you know what to ask and what to avoid.
Call a pro when…
- You are considering building up instead of building out
- The existing foundation or framing may need load verification
- The project adds bedrooms, bathrooms, stairs, HVAC zones, or major utility extensions
- The roof must be removed, raised, rebuilt, or heavily modified
- You need realistic preconstruction pricing before committing to full plans
Repair or replace?
A second story can preserve yard space and avoid some new foundation work, but it can be more disruptive than building out. A ground-floor addition may be simpler if the lot has room and the foundation/site work is manageable.
Need a cleaner scope before you call around?
Use the home additions checklist to compare the same work, questions, cleanup, and warranty before choosing a local company.
Related questions
Is it cheaper to build up or build out?
It depends on the house and lot. Building up can avoid some new foundation work but adds roof, stair, structural, and disruption costs. Building out needs foundation and site work but may be simpler.
Can I live at home during a second-story addition?
Sometimes for a partial or phased project, but many second-story additions require temporary relocation because of roof removal, structural work, dust, utility shutdowns, and safety.
Do I need an architect and engineer?
Usually yes. A second story changes loads, rooflines, stairs, egress, and permits. A design-build firm may coordinate both, but those roles still need to be covered.