The cost of adding a second story to a bungalow starts with the size of the new floor. According to Angi, second-story additions run about $100 to $300 per square foot nationally. At that range, a full second floor over a 1,000-square-foot bungalow comes to roughly $100,000 to $300,000 before design, engineering and any time living elsewhere, and a partial second story over part of the house costs less in total. Where your project lands in that range depends on how much structural work the existing house needs, how many bathrooms go upstairs, and the finishes you choose.
Norman Builders is a design-build home builder founded in 2007 by Ryan Norman, with an office in Newton, NH. Second- and third-level additions are part of our home additions work across the Merrimack Valley, the North Shore, the Seacoast and southern New Hampshire. This guide covers what drives the cost of building up on a one-story house, and how to plan it.
Cost of Adding a Second Story to a Bungalow
Average Cost Estimates
- Per square foot: about $100 to $300 nationally for second-story additions, according to Angi. Ground-level additions run about $80 to $200 by the same source.
- Whole floor: multiply the new floor area by that range for a first rough number, then add design, engineering, permits and temporary housing.
- Our area: national averages are a starting point only. For a budget you can rely on, price the plans for your house with a builder.
For how addition costs break down line by line, see our home addition cost guide and the home addition cost calculator.
Full vs. Partial Second Story
- Full second story: a new floor over the whole footprint. The entire roof comes off, and it gives the most new space, often enough for several bedrooms and a bath.
- Partial second story: a new level over part of the house, such as the bedroom wing. Less roof comes off and less structure is involved, so the total is lower, though the cost per square foot can stay similar.
- Dormers and attic space: on a bungalow with a steep roof, adding dormers to an existing attic can create usable rooms without a full new floor, if the space can meet code for ceiling height and stairs.
- Room over a garage: building over an attached garage is another way to go up without opening the main roof. See our guide to the cost of building a room over a garage.
Factors Influencing Costs
- Structure and foundation: most one-story houses were not designed to carry another floor. A structural engineer reviews the foundation, walls and first-floor framing, and reinforcement, if needed, is one of the biggest variables in the budget.
- Roof removal and weather protection: the old roof comes off, the house has to be protected while it is open, and a new roof goes on top. On a full second story, you get a new roof as part of the job.
- The staircase: a new stair takes floor space on the first floor, which can mean giving up a closet or reworking a room. Under the 2021 International Residential Code, stairs generally need to be at least 36 inches wide, with risers no taller than 7 3/4 inches and treads at least 10 inches deep, so plan the space early.
- Heating, cooling, electrical and plumbing: the existing system may not reach or heat a new floor, the electrical service may need an upgrade, and upstairs bathrooms need drains and vents that line up with what is below.
- Matching the house: siding, trim, windows and roof pitch should make the new floor look like it was always there.
- Older-home surprises: many bungalows predate 1978. Work that disturbs lead paint falls under the EPA's Renovation, Repair and Painting rule, and asbestos in old materials has its own handling rules.
- Temporary housing: with the roof open and systems disconnected, many families move out for part of the job. Budget for rent or a stay with family.
- Permits, zoning and septic: town fees, height limits, setbacks and, if bedrooms are added, septic capacity.
Planning Your Second Story Addition
Importance of Professionals
- Structural engineer: confirms whether the house can carry the new floor and designs any reinforcement. This comes before final design.
- Designer or architect: lays out the new rooms, the stair and the exterior so the house looks right from the street.
- Builder: prices the plans, sequences the roof-off stage and coordinates the trades and inspections. In a design-build setup, one team handles design and construction under one contract; we work with designers and architects on the plans, then an experienced project manager runs the schedule and budget.
Permits and Inspections
Expect a building permit plus electrical, plumbing and mechanical permits, with inspections at each stage. Before design goes far, check the zoning rules with your town:
- Height limits: the maximum building height in your zone, and how the town measures it.
- Nonconforming houses: many older bungalows sit closer to a lot line than current zoning allows. Adding a story to a house like that can need approval from the zoning board.
- Septic: in Massachusetts, Title 5 sizes septic systems by the number of bedrooms, and New Hampshire also sizes them by bedrooms. New upstairs bedrooms can mean a septic review or upgrade.
Comparing Building Up vs. Building Out
| Building up (second story) | Building out (ground level) | |
|---|---|---|
| Cost per sq ft (Angi, national) | About $100 to $300 | About $80 to $200 |
| Foundation | Existing foundation, reinforced if needed | New foundation |
| Roof | Old roof removed, new roof built | New roof tied into the existing one |
| Yard and lot | Keeps the yard; works on small lots | Uses yard; needs room within setbacks |
| Living at home | Often move out for part of the job | Usually stay home for most of the job |
| Best for | Bedrooms, bathrooms, offices | Kitchens, family rooms, first-floor suites |
Benefits of Building Up
- More living space without giving up yard, which matters on the small lots many bungalows sit on.
- Bedrooms upstairs can free the first floor for living space.
- A new roof comes with the project.
Challenges of Building Up
- The foundation and walls may need reinforcement.
- The roof-off stage exposes the house to weather.
- The stair takes first-floor space.
- The disruption is greater, and moving out for part of the job is common.
If you live in a ranch rather than a bungalow, our guide to ranch home additions compares building up and out for that house style.
From Our Projects
Our published addition case studies are ground-level additions, not second stories, but they show what goes into adding major space to an existing house and what that work costs in our area:
- Two-bedroom addition and primary suite, Amesbury, MA (completed 2025, budget band $700,000): two new bedrooms and a primary suite with a primary bath. We matched the rooflines, siding and window proportions, the same problem a second story has to solve. The homeowners chose to add on rather than move as their family grew.
- Coastal kitchen and spa-inspired bath addition, Andover, MA (completed 2024, budget band $700,000).
- Navy and white kitchen addition, Andover, MA (completed 2024, budget band $650,000).
Big structural projects can mean time away from home. Dan M. of Andover, whose project with us included "significant structural work, framing, roofing, plumbing, HVAC," wrote: "With two little kids we needed to move out of our house for 4 months." He added that the project "was finished ahead of schedule, on budget." And for a small house that needed more room, Brad and Sara R. wrote that our addition and renovation "transformed our small two bedroom cottage into a beautiful house."
Frequently Asked Questions about Second Story Additions
Is it cheaper to add a second story or build out?
Per square foot, building out is usually somewhat cheaper. According to Angi, ground-level additions run about $80 to $200 per square foot nationally and second-story additions about $100 to $300. Building up can still be the better choice when the lot is small, setbacks leave no room to the side or back, or you want to keep the yard. A second story also brings costs a ground-level addition does not: opening the roof, an engineer's review, a new staircase and sometimes living elsewhere during the work.
Can you add a second story to a bungalow?
Often, yes, but the existing house decides. A structural engineer has to confirm the foundation, walls and first-floor framing can carry the new level, or design the reinforcement. Zoning has to allow the extra height, and if the house already sits closer to a lot line than current zoning allows, adding a story can need zoning board approval. If the new floor adds bedrooms and the house is on septic, the septic system has to be sized for them.
How long does it take to build a second story?
Our renovation process guide puts a typical home addition at 3 to 9 months of work, and a second story can take longer because of the structural and roof work. Add time before that for design, engineering and permits. The roof-off stage is the most weather-sensitive part of the job, so the season matters in New England.
What are the most common unexpected costs?
Structural reinforcement the engineer finds is needed once walls are opened, rot or damage in the old roof framing, an electrical service too small for the new load, heating and cooling that cannot reach the new floor, lead paint or asbestos in older homes, and temporary housing if the job runs long. Keep a contingency in the budget for these.
Can I save money by doing some work myself?
Not on the structure, roof, wiring or plumbing: those need licensed trades, permits and inspections, and mistakes on a second story are expensive to undo. Some homeowners save by doing finish work such as painting after the inspections are done. Agree on that with your builder in writing before the job starts, so the schedule and responsibilities are clear.
Thinking About Building Up?
We start with an initial consultation about budget, needs and time frames, and define an estimated project cost before design goes further. Call Norman Builders at (978) 833-7337 or request an estimate.
