Half bath in a closet
$25k–$45k
- Framing and a new door opening
- Drain, vent and supply tie-in
- Toilet, vanity and mirror
- Tile floor and painted walls
- Exhaust fan ducted outside
- Plumbing and electrical permits
Bathroom addition · Licensed & insured · Permits pulled for you
Bathroom addition with the layout and connections assessed together.
The cost of a new bathroom depends less on tile than on one question: how far is the new drain from the main sewer line? A licensed supervisor traces your pipes, checks the space and the zoning, then prices three routes: a converted closet, a converted room or a bump-out addition.
Text a photo of the spot you have in mind. A supervisor who plans additions replies within 5 minutes during business hours.
- $45k–$85kTypical full bath add
- 6–9 wksInside-the-house build
- 4.9410 reviews
- 24hWritten estimate
What happens after you text us
The first question is where the pipes are. We ask it in the first text.
A new bathroom lives or dies on its drain. The supervisor asks where the nearest existing bathroom is, requests a photo of the basement or crawl space below the spot, and sets up a visit to trace the lines.
- The distance to the nearest drain decides most of the price
- A photo from below the spot shows how the pipe can run
- Zoning and septic questions answered before the visit
We have one bathroom for five people. There is a big hall closet upstairs next to the kids' rooms, could that become a bathroom?
Hi Paul, this is Tom, I plan our bathroom additions. Closets often work. Is the existing bathroom on the same floor, and how far is it from that closet?
Same floor, maybe 12 feet down the hall.
That is a good sign, the new drain can likely join the same stack. Could you send a photo of the basement ceiling under that closet? It shows me which way the joists run.
Sent. It is open, no drywall down there.
Perfect, open joists make the drain run easier. I can come Thursday at 6 to trace it, and you would have written prices by Friday evening.
What a bathroom addition costs
Adding a bathroom costs $25,000 to $175,000. Where it goes matters more than what goes in it.
Most families add a full bath inside space they already have, such as a spare room, an attic or a basement corner. Building out from the house costs roughly twice as much, because it adds a foundation, walls and a roof.
Full bath in existing space
$45k–$85k
- New walls framed and insulated
- Drain run to the main stack
- Tiled shower or tub with membrane
- Vanity, toilet and fixtures
- Circuits, GFCI and lighting
- Ejector pump if below the sewer
Bump-out addition
$90k–$175k+
- Foundation and footings
- Framed walls, roof and siding
- Window matched to the house
- Full bathroom inside the addition
- Heating and cooling extended
- Zoning, permits and engineering
Estimate the cost of a new bathroom
Pick the route, the size of the new bathroom and the type of house. The figure responds to each choice, based on what our addition supervisors quote.
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 figure into a written addition priceWhere the money goes
Plumbing is the biggest line on a new bathroom. Finishes come well after it.
Averages from our recent full-bath additions built inside existing space. Running a new drain, vent and water lines to a room that never had them costs more than the tile, vanity and fixtures put together.
Get my itemized addition estimate
Convert space or build out
Convert space you already have first. Build out only when nothing inside will do.
Building out from the house adds a foundation, a roof and zoning review, which roughly doubles the price and the calendar. At the visit we look at six things and write down which route fits your house.
| What we find at the visit | We recommend |
|---|---|
| A closet or spare room sits near an existing drain | Convert space |
| Every inside room is already in daily use | Build out |
| The basement has headroom and a nearby floor drain | Convert space |
| You need a bedroom with its own bath on the main floor | Build out |
| The lot has room within the zoning setbacks | Build out |
| Your budget for the bathroom is under $80,000 | Convert space |
How long it takes
A bathroom built inside the house takes six to nine weeks, and permits start the clock.
A half bath in a closet takes four to six weeks. A bump-out takes twelve to sixteen, because the foundation must cure and be inspected before the walls go up. Permit review time is written into your schedule from day one.
Weeks before
Survey and permits
Pipes traced, space measured, drawings made, permits and zoning filed. Nothing is cut until approval.
Weeks one and two
Framing and drain run
Walls framed, new drain and vent run to the stack, supply lines and wiring pulled, rough-in inspected.
Weeks three to five
Insulate, board, tile
Insulation, drywall and cement board, shower waterproofed and flood-tested, then floor and wall tile.
Final weeks
Fixtures and final permit
Fixtures set, fan and lights live, paint and trim, final inspection signed, walkthrough with you.
Before and after
Three houses that gained a bathroom, and where each one came from.
What a new bathroom is built from
The hidden parts are named too, not just the tile and the vanity.
Most of a bathroom addition sits behind the walls and under the floor. Your estimate names the pump, the pipe and the sheathing along with the finishes, because those parts decide how the room holds up.
Upflush and ejector systems
Saniflo upflush toilets for small half baths and Liberty Pumps sealed ejector basins for full basement baths lift waste to the sewer.
PEX supply lines
Uponor or similar PEX tubing runs hot and cold water in one piece from the manifold, with fewer fittings inside the walls.
Exterior sheathing
For a bump-out, Huber ZIP System panels combine sheathing and a weather barrier, with taped seams that keep wind and water out.
Windows
Andersen or Pella windows sized to match the house, with obscure glass for privacy and a sill set high enough for a shower wall.
Heating and cooling
A Mitsubishi ductless mini-split or a new duct run keeps an added bathroom as warm as the rest of the house in winter.
Exhaust ventilation
A Panasonic fan ducted through the wall or roof, sized at about 1 cubic foot per minute for each square foot of floor.
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 in your house
Three people build your new bathroom, start to final permit.
An addition means more trades than a remodel, but you still deal with one supervisor. Every person on site is background-checked and introduced by name, and new faces only appear after a text telling you who and when.
Addition supervisor
Handles permits and inspections, sends your daily update.
Master plumber
Runs the new drain, vent and supply lines and sets fixtures.
Lead carpenter
Frames walls, sets the door and builds any bump-out shell.
Recent bathroom additions, real numbers
Three added bathrooms, three routes, three final permits signed.
Hall closet into a half bath
- Final price
- $31,700
- Duration
- 5 weeks
- Location
- City, ST
Basement full bath with pump
- Final price
- $68,400
- Duration
- 8 weeks
- Location
- City, ST
Main-floor bump-out bath
- Final price
- $137,500
- Duration
- 14 weeks
- Location
- City, ST
Your house is not average
Why you need a new bathroom changes how we build it.
Every addition starts from the three routes above. These are the reasons families add a bathroom, and what each one does to the scope, the price or the schedule.
One bath for a growing family
Five people and one bathroom means a line every morning. A half bath upstairs near the bedrooms often ends it for a third of the cost of a full bath, and it can usually be built without touching the existing one.
Price a second bathroom for usA parent moving in downstairs
A main-floor bedroom with its own accessible bath lets a parent live with you and skip the stairs. We plan a curbless shower, wide door and grab bar blocking, and price whether it fits inside or needs a bump-out.
Plan a main-floor bath for a parentAdding value before a sale
A house with one bath often sells for less than its three-bedroom neighbors with two. A half bath in existing space is the cheapest route to that second bath, and we can tell you if it fits before you call an agent.
See if a second bath fits my houseAn older house with one bath
Many older homes were built with a single bathroom and cast iron drains. We check the stack's condition and size, price any section that must be replaced to tie in safely, and plan around plaster walls.
Price a bath for my older houseA house you just bought
New owners often find the house works except for the bathroom count. We can build the addition in its own phase, ahead of the cosmetic work, so the plumbing lines are in before you finish the floors and paint.
Plan my new house bathroom firstStrict permit rules in your town
Some towns review additions closely, with setbacks, lot coverage limits and septic records. We file the drawings, answer the plan reviewer and add the review weeks to your schedule so the dates stay honest.
Handle my bathroom addition permitA bump-out in a cold climate
Footings must sit below the frost line, which can be 42 inches or deeper in northern states. We price the deeper foundation, insulate the floor and walls to code, and keep pipes out of any exterior wall.
Price a winter-proof bath additionA basement suite for a relative
A full bath is the piece that turns a finished basement into a suite for a grown child or a relative. We price the ejector pump, the egress rules if there is a bedroom, and the shower placement near the stack.
Price a basement bath for a relativeWhat this service is
A bathroom addition, explained from the drain up.
Bathroom addition work is the construction of a new bathroom where the house had none, either inside existing space such as a closet, spare room, attic or basement, or in new square footage built out from the house. It includes the new drain, vent and water lines tied into the existing system. ProBuild Remodeling builds it as a licensed general contractor with permits under our license.
The service covers framing, plumbing tie-in, ejector or upflush systems where the drain sits below the sewer, electrical circuits, ventilation, waterproofing, tile, fixtures and, for bump-outs, the foundation, walls and roof. It includes drawings, permits and inspections. It does not include remodeling a bathroom that already exists, which is a separate bathroom remodeling service.
It is for families who have outgrown one bathroom, homeowners bringing a parent to live with them, and buyers of an older house with too few baths. It is not for someone who only wants to enlarge a current bathroom into a closet, which is priced as a remodel with a new layout.
Terms on a bathroom addition estimate
- Tie-in
- The point where the new drain, vent and water lines join the existing plumbing. Its distance and depth set much of the cost.
- Main stack
- The large vertical drain and vent pipe that runs from the roof to the sewer. New bathrooms usually connect to it.
- Ejector pump
- A sealed basin with a pump that lifts waste from a bathroom below the sewer line up to the main drain.
- Upflush toilet
- A toilet with a macerating pump behind it, suited to a half bath where a gravity drain is not practical.
- Setback
- The minimum distance zoning requires between a building and the property line. It limits where a bump-out can go.
- Bump-out
- A small addition that extends one wall of the house outward, with its own foundation and roof, to make room for a new space.
- Frost line
- The depth to which the ground freezes in winter. Footings for an addition must sit below it so the ground does not heave.
- Subpanel
- A secondary electrical panel fed from the main one, used when the main panel has no room for the new circuits.
Bathroom addition questions
Eight questions to answer before you add a bathroom.
How much does it cost to add a bathroom?
A half bath carved out of a closet costs $25,000 to $45,000. A full bath built inside a spare room, attic or basement costs $45,000 to $85,000. A bump-out addition with its own foundation and roof runs $90,000 to $175,000 or more.
Can you add a bathroom anywhere in the house?
Almost anywhere, but the price climbs with distance from the existing drain and vent stack. Spots directly above, below or beside an existing bathroom are the cheapest to plumb. A basement spot below the sewer line needs a pump.
How much space do I need for a new bathroom?
A half bath fits in about 18 to 25 square feet, the size of a deep closet. A full bath with a shower needs about 35 to 40 square feet, roughly 5 by 8 feet, to meet code clearances around the toilet and sink.
Does adding a bathroom increase home value?
Usually, most of all when the house has fewer bathrooms than similar homes nearby. Going from one bath to two often helps most. A half bath in existing space tends to return a larger share of its cost than a bump-out.
How long does it take to add a bathroom?
Four to six weeks for a half bath in a closet, six to nine for a full bath in existing space, and twelve to sixteen for a bump-out. Permit review can add two to six weeks before work starts, depending on the town.
Do I need an ejector pump for a basement bathroom?
Only if the new fixtures sit below the sewer line leaving the house. Many basements have the sewer pipe exiting through the wall a few feet up, which means a pump is needed. We check the depth at the visit.
Can a septic system handle another bathroom?
Often it can, but some counties size septic systems by bedrooms or fixtures and ask for a review when you add a bath. We check your permit record and tell you whether a review or an upgrade is likely.
Will the new bathroom match the rest of the house?
Inside, it is finished like any new bathroom. For a bump-out, we match the siding, roofing and window style so it looks original from the street, and we tell you in writing if an exact match is no longer made.
Bathroom additions near you
Your remodeling address, within our service area.
Additions depend on local zoning and permit rules, so every one is planned by a crew that works in your area under your state license. Our licenses page lists each number.
- 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 bathroom addition estimate
Show us where the bathroom would go. We will tell you if the drain can reach it.
Send the your answers and a photo of the spot. An addition supervisor replies within 5 minutes during business hours and books a visit to trace the pipes.