Bump-out
$35k–$75k
- Up to about 100 sq ft added
- Pier or short-wall foundation
- Roof tied into the existing eave
- Windows and siding matched
- Flooring run through to the room
- Permit and inspections
Home additions · Licensed & insured · NARI member
A home addition that adds the room you are missing,
not a year of surprises.
A licensed addition supervisor walks your lot, checks setbacks and where the footings can go, then sends a written estimate in three sizes within 24 hours. A small bump-out starts near $35,000; a full new room with its own heat and power usually runs $90,000 to $180,000.
Text two photos of the wall you want to build off. A supervisor answers within 5 minutes during business hours and tells you if the lot allows it.
- $250–$450Per sq ft, typical
- 12–18 wkSingle-room build
- 4.9410 reviews
- 24hWritten estimate
What happens after you text us
The person who walks your lot answers. Not a scheduling desk.
Most addition questions are really lot questions: how close to the property line, where the footings go, which roof to tie into. The first text exchange sorts that out and books a visit with a tape measure, not a sales pitch.
- A licensed supervisor who will also run your build
- Two photos and your address are enough for a setback check
- Lot visit and estimate dates agreed in the first thread
Hi, we want to add a family room off the back of our ranch. Maybe 16 by 20. The kitchen is on that side.
Hi Karen, Dave here, I run addition builds for ProBuild Remodeling. 16 by 20 off a ranch is a very buildable room. Can you send a photo of that back wall and your plat or survey if you have it? I want to see how far you are from the rear line.
Sent both. There is a patio there now and a big window over the sink.
Thanks. You have about 38 feet to the line, so setbacks are fine. The patio comes out, and that window likely becomes a wide opening into the new room. I can walk it Saturday at 9 and have your three sizes in writing Tuesday.
Saturday is good. Should we call the city about the permit first?
No need. We check zoning before the visit and file the permit ourselves once you pick a size. See you Saturday.
What a home addition costs
A home addition costs $35,000 to $320,000. The size and the plumbing set the price.
Ground-level additions with mid-range finishes, matched siding and roofing, and heat and power run from the house. A dry room like a den or office costs far less per foot than one with a bathroom. Your estimate shows all three sizes side by side.
New room
$90k–$180k
- Excavation and poured footings
- Framing, sheathing and insulation
- Roof matched to the house
- Heating and cooling extended
- Electrical circuits to code
- Drywall, trim, paint, flooring
Addition with bath
$180k–$320k+
- Everything in New room
- Full bathroom with plumbing
- Sewer or septic connection
- Structural engineer's drawings
- Electrical panel upgrade
- Separate zone for heat and AC
Price your addition in ten seconds
Choose the type of addition, the floor area and the age of the house. The range moves as you pick, using the same three sizes our addition supervisors quote from.
A range, not a quote. Your written estimate comes after the visit and does not change once you approve it.
Typical range for your answers
Turn this range into a written addition estimateWhere the money goes
Almost half the budget is the shell. Finishes are the smaller share.
Averages from recent single-room additions we built. Foundation, framing and roof are fixed costs you pay before a single finish is chosen, which is why a bump-out costs more per foot than a full room.
Get my itemized addition estimate
Bump-out or full addition
Bump out when a few feet fix the room. Build a full addition when you need a new one.
A bump-out pushes one wall out a few feet, often without a full foundation. A full addition is a new room on new footings. At the lot visit we check six things and write down which one your house calls for.
| If this is true | We recommend |
|---|---|
| The room works but feels about four feet too tight | Bump-out |
| You need a separate room with its own door | Full addition |
| The lot is close to a side or rear setback line | Bump-out |
| You want a bathroom or a bedroom that counts as one | Full addition |
| Your budget is under about $75,000 | Bump-out |
| You need more than 150 square feet of new floor | Full addition |
How long it takes
A single-room addition takes about four months, and you keep living in the house.
A bump-out takes 6 to 10 weeks, an addition with a bath 18 to 26. The existing wall stays closed until the new room is weathertight, so the house is never open to the rain.
Before day one
Survey, design, permit
Setbacks confirmed, plans drawn, engineer's stamp if needed, permit filed. Four to eight weeks of paperwork.
Weeks one to three
Dig and pour
Utilities marked, footings dug and inspected, foundation poured and cured before any framing begins.
Weeks four to ten
Frame, roof, dry-in
Walls and roof framed, tied into the house, windows set and wrapped so the new room is sealed from weather.
Final weeks
Open up and finish
The old wall is opened last, then insulation, drywall, floors and paint, final inspection and your walkthrough.
Before and after
Three houses, one wall each that became a room.
What your addition is built from
Every material in the shell is named in writing, because you never see it again.
Once the drywall is up, nobody can check what is behind it. Your estimate names the foundation, the framing, the wrap and the windows, so two addition quotes can be compared line by line.
Poured footings
Concrete footings below the local frost line, sized by soil and load. A crawlspace or slab on top, whichever matches the house.
Framing and sheathing
Kiln-dried lumber with ZIP System or plywood sheathing and taped seams, so the walls are straight and the envelope stays tight.
Insulation
Fiberglass batts or closed-cell spray foam to current energy code, so the new room is never the cold room of the house in winter.
Windows
Andersen, Pella or Marvin windows with low-E glass, matched in style and grille pattern to the windows you already have.
Roofing and siding
Architectural shingles from GAF or Owens Corning and siding matched to the house, with ice-and-water shield at every tie-in.
Heating and cooling
A ductless mini-split from Mitsubishi or Daikin, or ductwork extended from your system when it has the capacity to spare.
Written into every contract
Six promises you can hold us to.
The approved price is the final price. Change orders only with your written approval.
A credit for every working day of delay we cause. Weather and inspections excepted, in writing.
Dust barriers, floor protection and a clean-up before we leave. Your home stays livable.
A text or email every working day with photos and tomorrow's plan, or the day is free.
Workmanship warranty in writing, transferable to the next owner, backed by a fixed address.
A small deposit, then you pay only for work that is already completed, inspected and photographed.
Who is on your lot
One supervisor from footings to paint, with the same crew leads throughout.
An addition moves through more trades than any room remodel. You meet the three people who coordinate all of them before excavation starts, and they are the ones who stay.
Addition supervisor
Runs the build, meets every inspector and answers your texts.
Framing lead
Frames the walls and roof and ties both into your house.
Finish carpenter
Trim, doors and the opening between old and new rooms.
Recent additions, with the real numbers
Three additions, three budgets, all finished on the contract date.
Ranch family room, 320 sq ft
- Final price
- $128,400
- Duration
- 15 weeks
- Location
- City, ST
Breakfast nook bump-out
- Final price
- $46,900
- Duration
- 8 weeks
- Location
- City, ST
Bedroom and bath wing
- Final price
- $236,000
- Duration
- 22 weeks
- Location
- City, ST
Your lot is not average
Your house and lot are different. Here is how the estimate changes.
Every addition starts from the same three sizes, then moves for what makes your house and lot unusual. Pick the case that sounds like yours.
An older house
Additions on older homes meet plaster, balloon framing and floors that are not level. We plan the tie-in so the new floor lines up with the old one, and your estimate names the lead-safe steps if the old paint needs them.
Price an addition on my older houseA narrow or small lot
When the side setback is only a few feet, the answer is often a rear addition or a bump-out on piers. We pull the survey before the visit, so the design you fall for is one the zoning office will actually approve.
Check what my small lot allowsA growing family
A new bedroom close to the others, a family room where you can see the kids from the kitchen, or a bath that ends the morning line. We plan the room around the next ten years of your family, not only the next one.
Price a room for my growing familyA parent moving in
A ground-floor bedroom with its own bath, a wide door and no step keeps a parent close and independent. We write the estimate for the adult child who is organizing it and send a copy to whoever needs to see it.
Plan a ground-floor room for a parentKeeping the cost down
A simple rectangle under a shed roof, no plumbing, and windows in standard sizes can take a third off the price. We show which choices save money for good and which only move the cost to a later repair.
Price a budget-friendly additionAn HOA or strict zoning
Some neighborhoods review siding color, roof pitch and window style before the city will. We prepare the HOA packet with drawings and samples, so the approval arrives before your spot on our build calendar.
Get my addition through HOA reviewSnow and deep frost
Footings must sit below the local frost line, and a new roof tied into an old one is exactly where ice dams start. We dig to local depth and run ice-and-water shield across every seam where the two roofs meet.
Price a cold-climate additionA room to work from home
A quiet office needs a solid door, sound insulation in the shared wall, extra circuits and a network drop. We treat it as a working room, not a spare bedroom, and price the details that make video calls bearable.
Price a home office additionWhat this service is
A home addition, defined the way we quote it.
Home addition is the construction of new, heated living space onto the side or back of an existing house at ground level, on its own foundation or on piers, and joined to the house through an opened wall and a tied-in roof. ProBuild Remodeling builds it as a licensed general contractor, with zoning, engineering, permits and inspections handled under one contract.
The service covers bump-outs of a few feet, single new rooms such as family rooms, dens and offices, and larger ground-floor wings with a bedroom and bathroom. It includes site work, foundation, framing, roof, windows, siding, heating, electrical and interior finishes. Building upward is a second story addition, and a detached unit is an ADU; both have their own pages.
It is for homeowners who like their house and neighborhood but have run out of room, and for families bringing a parent home. It is not for lots with no buildable area left under zoning, or for owners who only need to reorganize existing rooms, where a remodel costs less and is faster.
The words you will see on your addition estimate
- Setback
- The minimum distance zoning requires between your house and each property line. It decides where an addition can go.
- Bump-out
- A small addition that pushes one wall out a few feet, often supported on piers or a cantilever instead of full footings.
- Footing
- The concrete base below the foundation wall, set under the frost line so the addition does not heave or settle.
- Tie-in
- The joint where the new roof and walls meet the old ones. Flashed and sealed so water cannot find the seam.
- Dry-in
- The point when the new room has its roof, windows and wrap on, so rain can no longer get in during the rest of the build.
- Subpanel
- A second breaker box fed from your main panel, used when the main has no room for the new circuits the addition needs.
- Survey
- A drawing of your lot showing the property lines and the house. Zoning offices want it with every addition permit.
- Contingency
- Ten to fifteen percent held for surprises like bad soil or rot. Spent only with your written approval, returned if unused.
Questions we hear on every addition call
The eight questions people ask before adding a room.
How much does a home addition cost per square foot?
Most ground-level additions land between $250 and $450 per square foot with mid-range finishes. Small bump-outs cost more per foot because the foundation and roof tie-in are fixed costs. Rooms with a bathroom sit at the top of the range because of plumbing and sewer work.
Do I need a permit to build a room addition?
Yes, every heated addition needs a building permit, and most also need zoning approval for setbacks and lot coverage. We check zoning before the visit, draw the plans and file under our license, so approval usually lands during the design weeks.
How long does it take to build a home addition?
A bump-out takes 6 to 10 weeks of construction, a single new room 12 to 18, and a larger addition with a bathroom 18 to 26. Add four to eight weeks before that for survey, design and permit.
Can we stay in the house while you build the addition?
Yes. The new room is built and sealed from the outside while the existing wall stays closed. We open the connection near the end, behind dust walls, so the disruption inside lasts about a week or two.
Is it cheaper to build out or build up?
Building out is usually cheaper per square foot when you have yard to spare, because the existing roof and foundation are not touched. Building up saves yard but needs structural work on the house below, which is why it has its own page.
Will the addition match the rest of my house?
That is the goal we write into the estimate: matched roof pitch, siding profile, window style and interior trim. When a product is discontinued we tell you before the build and propose the closest match or a full-wall reside.
Does a home addition add value to the house?
A well-matched addition that adds a bedroom, a bath or a family room usually recovers a good share of its cost at sale, and more in neighborhoods short on space. A room that looks added on recovers less, which is why matching matters.
What if the soil or foundation is a problem when you dig?
We photograph it, price the fix as its own line and explain what the engineer requires. Nothing is poured until you approve it, and the cost comes from the contingency set aside in your contract.
Home additions near you
Your remodeling address, within our service area.
Setbacks, frost depth and permit rules change from town to town. Each addition is built by a local crew under the license of the state it stands in.
- Maine
- New Hampshire
- Massachusetts
- Rhode Island
- Connecticut
- New York
- New Jersey
- Pennsylvania
- Delaware
- Maryland
- Virginia
- North Carolina
- South Carolina
- Georgia
- Florida
- Check your remodeling address
Free addition estimate
Send your answers today. Get three addition sizes priced in writing.
Your addition supervisor reads the answers, checks the lot against zoning, texts you within 5 minutes during business hours and sets the lot visit in the same thread.