A tub to shower conversion on Cape Cod takes the five foot alcove tub out of a 1950s to 1980s Cape or ranch and builds a tiled or paneled walk-in shower in the same footprint. It looks like a swap. It is a rebuild of the wettest corner of the house: the drain usually moves, the floor gets a sloped pan, the walls get a real waterproofing system, and whatever rot has been hiding behind the tub gets fixed before anything new goes in. Coast Carpentry Home Group does this work across the Cape from our shop at 14 Parker Rd, Unit A in Osterville.
We are carpenters first, and the tile is the last day of the work. The framing, subfloor and waterproofing before it decide whether the shower is still dry in fifteen years. No prices here. A real number takes a look under your bathroom floor.
A tub to shower conversion removes the bathtub and its surround, repairs the framing and subfloor behind them, relocates the drain and valve, builds a sloped and waterproofed shower pan, and finishes the walls in tile or solid surface panels with glass to contain the water. Coast Carpentry Home Group builds walk-in showers in all 15 Cape Cod towns. Ask us to look at your bathroom.
Key takeaways
- A standard five foot tub alcove becomes a shower about 60 inches by 30 inches, which is a generous single shower and clears the 900 square inch, 30 inch minimum in the residential code Massachusetts adopts with room to spare.
- The drain is the hard part. A tub drain sits at one end against the wall and a shower drain wants the middle of the floor or a trench along one edge, so the drain line almost always moves, and what is under the bathroom (basement, crawlspace, finished room or slab) decides how much work that is.
- Grout and tile are not waterproofing. The shower stays dry because of a sloped pan, a bonded sheet or liquid membrane that turns up the walls and over the curb, and corners and niches sealed as part of that system.
- Behind a Cape Cod tub on an exterior wall we expect to find a wet sill, soft subfloor at the drain and sometimes old wiring. That gets repaired before the new shower is built on it, with photos to you the day we find it.
- A conversion needs a plumbing permit and a building permit, and it does not trigger Title 5 because the fixture count and the bedroom count do not change. Coast Carpentry Home Group builds under a Massachusetts Construction Supervisor license with a lifetime workmanship warranty.
What does a tub to shower conversion involve on a Cape Cod house?
On a Cape house the conversion runs in a fixed order: protect the house and pull the tub and surround, open the wall and floor and repair what is wet or soft, move the drain and raise the valve, frame the curb or recess the floor, build and waterproof the pan and walls, tile or panel, then set the glass last. Each step depends on the one before it.
Most of the bathrooms we convert on the Cape look the same on day one: a five foot alcove tub with a shower head over it and a surround from whenever the bath was last touched, in a Cape or ranch built from the 1950s through the 1980s in Yarmouth, Dennis, Barnstable, Falmouth or Sandwich, where nobody has run a bath in years.
We seal the room off, pull the surround and lift the tub out, which in an older Cape sometimes means cutting a cast iron tub into pieces on the spot. The wall comes open to the studs and the floor comes up to the subfloor. Plumbing, framing, waterproofing and tile follow in that order, and glass is measured last to the finished opening. A primary bath we built at 84 Alden Drive shows the full version: a long double shower in marble with two rain heads, a pebble floor pitched to the drain and a sliding glass door, finished the way a shower should be when nothing is being saved.
Why is the drain the hardest part of the job?
A tub drains at one end, tight to the wall. A shower floor drains at its center, or along one edge through a linear drain, and it needs a sloped pan above the drain and fall in the pipe below it. Moving that drain means working under the floor, and on a Cape house the space under the floor ranges from a full basement to a concrete slab.
A tub is a manufactured vessel with a drain at the foot. A shower is a floor built on site that has to pitch to its drain from every side, so the drain line almost always moves. What is under the bathroom decides how much work that is. Over a full basement, which is common in the Capes around Osterville, Centerville and the Sandwich village streets, the plumber works from below. Over a finished room, the ceiling below gets opened and patched. On a slab, and a good share of the 1960s and 1970s ranches in Yarmouth and Dennis sit on slabs, moving a drain means cutting concrete, and the project is a different size. Joists matter too: pipe has to slope toward the stack and the trap has to fit between the subfloor and the ceiling below, so we do not notch joists where it is convenient.
The valve moves at the same time, up from tub height to shower height, and under the code Massachusetts adopts it has to be a pressure balanced or thermostatic valve set so the water cannot exceed 120 degrees. With the wall open that is a small job. After the tile is on, it is a demolition.
Curb or curbless: which one can your floor take?
A curbed shower works on any floor structure and the code calls for a curb two to nine inches above the drain. A curbless shower needs the shower floor recessed below the bathroom floor, which means dropping the subfloor between the joists or building the rest of the floor up, and that is only possible when the framing and the room allow it.
The entry has to be decided before the pan is built, because it changes the framing, the drain and the waterproofing. A curb is the small threshold you step over. It works on every floor we have ever opened, and the waterproofing wraps up and over it so the top of the curb is not a path into the framing. The code we build to wants the finished curb at least two inches and no more than nine above the top of the drain, and the floor pitched between a quarter inch and a half inch per foot toward it.
Curbless is the better answer for anyone who wants this bathroom to still work for them in twenty years, and the more demanding build. The shower floor has to sit lower than the bathroom floor so the slope ends at the drain and not at the door. In a Cape with 2×8 joists and a basement below, that recess can be built by sistering and dropping the subfloor in the shower bay. In other houses it cannot, and the honest options are raising the rest of the bathroom floor a step, or a curb. We tell you which one your house allows at the first visit, after we have looked underneath.
What keeps a walk-in shower dry for the long haul?
A bonded waterproof membrane, either a sheet or a liquid applied product rated to the ANSI A118.10 standard, installed over a sloped pan and carried up the walls, over the curb and into every corner and niche as one continuous system. Tile and grout shed most of the water. The membrane behind them is what keeps the framing dry.
Tile is not waterproof and grout is not waterproof. A shower built on bare tile backer board with nothing behind it passes water into the studs and the subfloor for years before anyone sees it. The code Massachusetts adopts requires a liner behind a site built shower, from the old sheet lead and PVC pans through to a bonded sheet or liquid membrane that meets ANSI A118.10. The liner runs at least two inches above the finished threshold over a pre-sloped base, so water that gets through the tile still drains instead of pooling. On our conversions we use a bonded membrane carried over the whole wet area, pan, walls and curb, because it ties the floor and the walls into one skin instead of two parts hoping to meet.
Every penetration is a decision. A recessed niche is a hole through a waterproofed wall with four new inside corners, so it is built and sealed as part of the membrane, not cut in later. A bench is a small roof that has to be pitched to drain and wrapped like the rest. A rain head, a hand shower and body sprays each add a pipe through the skin, so we settle fixtures before rough plumbing, and a hinged shower door has to swing out under the code we build to.
What do we find behind a Cape Cod tub when it comes out?
Wet and often rotted framing where the tub met an exterior wall, a soft subfloor around the old drain, a window set inside the old tub alcove, galvanized or lead drain pieces in older houses, and wiring that was never meant to be near a shower. All of it gets repaired or corrected before the new shower is built, and you see photos the day we open the wall.
The area behind and under a tub is the most likely place in the house to be hiding water damage, and on the Cape the pattern is the exterior wall. A lot of Cape bathrooms put the tub against an outside wall under a window, and the joint where the surround met the sill has leaked a little for decades. Salt air and a wall that never fully dries do the rest. We find sills an awl sinks into, bottom plates gone soft and insulation holding water like a sponge. That framing is cut out and replaced and the wall gets a proper vapor detail before any backer board goes on, and it is the single biggest reason a conversion in an old Cape takes longer than one in a newer house.
A window inside the shower leaks unless it is handled on purpose, so we either build it into the waterproofed wall with a sloped sill and a wrapped jamb, or close the opening and bring light in another way. Under the floor, the subfloor around a drain that has wept for years is usually soft, and in a house built before the 1970s the trap can be galvanized or lead that has to come out anyway. None of this is a reason not to convert. It is the reason our estimate says in writing that hidden conditions get photographed and priced before any extra work happens.
How do you keep the moisture out of the rest of the house?
With an exhaust fan sized to the room, ducted to the outside through the roof or a gable, never into the attic, run on a timer or a humidity sensor so it keeps going after the shower stops. A walk-in shower without a tub puts more steam into the room than the old setup did, and a Cape bathroom in August already starts damp.
A walk-in shower puts more steam into the room than the tub did. Cape Cod summers sit at the humidity where a bathroom that cannot dry out grows mildew on the grout within a season. So the fan is part of the conversion, not an extra. We size it to the room, duct it in insulated pipe to a roof cap or a gable vent, and wire it to a timer or a humidity sensor so it runs after the last person steps out. Opening an older Cape attic and finding the old bath fan blowing into the insulation is common, and it explains more than a few stained ceilings and frosty roof decks we get called about in February.
Second homes add one more consideration. A lot of the Capes we work in sit closed up from October to May with the heat turned down, and a cold, shut bathroom with no air moving is the worst place for a damp pan. For a seasonal owner we talk through a fan that can run on a schedule, a drain that gets a splash of water now and then so the trap does not dry out, and a heat setting that keeps the room above the dew point.
Walk in shower installation: tile, solid surface panels or an acrylic base?
A fully tiled shower gives you any size, a bench and a niche, and the look most Cape homeowners want. Solid surface wall panels over a tiled or acrylic base cut the grout to almost nothing and clean easier. An acrylic base with tiled walls skips the site built pan and is the simplest build. All three can be built dry. The difference is look, layout freedom and maintenance.
We build all three and we will show you the trade-offs on your bathroom rather than sell you one. Tile is the most flexible: it uses the whole tub footprint, it takes a bench, a recessed niche, a linear drain and a curbless entry, and large format tile on the walls keeps the grout lines down. On the floor we use a small format or a pebble so the tile can follow the slope and give your feet some grip, in a matte or honed finish, never polished. Solid surface panels suit a hall bath or a rental: large sheets over a waterproofed wall, less grout, fewer sizes and a simpler look. A manufactured acrylic base with tiled walls takes the site built pan out of the job when the drain works with a stock size, at the cost of a visible lip and a footprint that rarely uses the full five feet. We still waterproof the walls above it the same way.
Whichever finish you pick, the carpentry under it is the same crew. Blocking for grab bars goes into the wall on every conversion whether or not a bar is going in now, because it costs almost nothing while the studs are exposed and it is a real job later through finished tile. A hand shower, a bench and a wider opening than the minimum are the other things we raise for anyone who plans to stay in the house.
Do you need a permit, and does Title 5 come into it?
Yes to the permits. Moving a drain and a valve takes a plumbing permit pulled by the licensed plumber, and the demolition, framing and waterproofing take a building permit from the town. No to Title 5. A tub to shower conversion does not add a fixture or a bedroom, so it does not trigger a septic inspection or an upgrade on its own.
Every Cape town handles the paperwork a little differently, but the shape is the same. Our licensed plumber pulls the plumbing permit for the drain and supply work and schedules the rough and final inspections. We pull the building permit under our Massachusetts Construction Supervisor license for the demolition, framing, subfloor repair and the shower assembly, and the inspector sees the pan before the tile covers it. An unpermitted pan nobody inspected is exactly what a buyer’s inspector writes up at a sale, which is one reason choosing a bathroom remodeling contractor on Cape Cod matters.
Title 5 is the question we hear most from anyone on a septic system. A conversion does not change the design flow of the house. Title 5 looks at bedrooms and, through them, at how much wastewater the system is sized for. Swapping a tub for a shower is one fixture for one fixture in the same room, so there is no trigger. Adding a bathroom where there was none is a different conversation, covered in our guide to what drives bathroom addition cost on Cape Cod.
When should you keep the tub?
Keep a tub when it is the only one in the house and you have young children, plan to sell to families, or rent to them in summer. Keep it when the bathroom is too small for a shower that meets the 30 inch minimum with a usable door swing. And keep it when the real problem is a failed surround, which can be rebuilt around the existing tub for less disruption.
We talk people out of conversions a few times a year, for one of three reasons. The first is the only tub in the house. A year-round family home with no bathtub is a harder sell, and a summer rental without one loses the families with small kids who book July. If it is the only one, think about who uses the house and who buys it next, and ask an agent, because we are builders.
The second is the room. A conversion needs a shower at least 30 inches in its smallest dimension with 900 square inches of floor, a 22 inch clear opening, and a door that swings out or a panel that does not block the toilet or the vanity. Most five foot alcoves clear that easily. A bath squeezed under a Cape’s roof slope where the ceiling drops below 70 inches over part of the floor sometimes does not, and we would rather tell you that than build a shower you cannot turn around in. The third is a failed surround on a tub that is fine. A yellowed fiberglass unit or failed grout can mean a new tiled surround around the tub you have, which is less work, keeps the tub for resale and still gets the waterproofing done properly.
What drives the cost of a tub to shower conversion on Cape Cod?
What is under the floor, what we find behind the tub, curb or curbless, tile or panels, and the glass. A conversion over a basement with sound framing, a curb and a stock glass door is the simple end. A curbless shower on a slab with rot repair, a window to rebuild and custom frameless glass is the other end. We quote after we have looked, never over the phone.
The drain location and the floor structure set the plumbing scope. Hidden conditions behind the tub set the carpentry scope. What does not change is the warranty. Coast Carpentry Home Group backs the workmanship on every conversion with a lifetime workmanship warranty: if something we built is not right because of how we built it, we come back and fix it at no cost, and the fixtures and panels carry their manufacturer’s warranty on top. For the bigger picture, read our guide to what a bathroom remodel costs on Cape Cod, and for the bench and casing side of a bath, our interior trim and finish carpentry guide.
Ready to lose the tub?
We will come out, look at what is under the floor and behind the wall, tell you whether your house can take a curbless entry, and put a written scope in front of you with the waterproofing system named. Schedule a bathroom visit and quote, or see everything we do on our Cape Cod bathroom remodeling page. More than 25 years of experience, a Massachusetts Construction Supervisor license, and one crew for the carpentry, the tile and the coordination with the plumber and electrician.
Frequently asked questions
How long does a tub to shower conversion take on Cape Cod?
Longer than a surround swap and shorter than a full bathroom remodel. The drain work and whatever is found behind the tub set the schedule, and the glass is measured after the tile is set, so it arrives last. A conversion over a basement with sound framing is a shorter job than a curbless shower on a slab with rot to repair. We give you a schedule after the first visit, with the demolition day findings as the one variable we name up front.
Can the drain stay where the tub drain was?
Sometimes. A linear drain set along the wall where the tub drain was can let the floor pitch toward the existing line, which avoids cutting concrete on a slab house or opening a finished ceiling below. It depends on the joist direction and the fall available in the pipe. We check it on every conversion before the layout is settled.
Is a curbless shower possible in an older Cape Cod house?
Often, but it is a framing question, not an age question. The shower floor has to be recessed below the bathroom floor, which means dropping the subfloor between the joists in the shower bay or raising the rest of the room. Over a basement or a crawlspace that is usually workable. On a slab it is a much bigger job. We look under the floor before we answer.
Do I need a permit for a tub to shower conversion in Massachusetts?
Yes. Moving the drain and valve requires a plumbing permit pulled by a licensed plumber, and the demolition, framing and shower assembly require a building permit from your town. The inspector looks at the waterproofed pan before tile covers it. Coast Carpentry Home Group pulls the building permit under its Massachusetts Construction Supervisor license and coordinates the plumbing and electrical permits.
Will converting the tub hurt resale on Cape Cod?
Not if the house keeps at least one tub somewhere. If this is the only tub, families with small children and summer rental guests notice, so weigh who uses the house and who buys it next, and ask a local agent. What always helps resale is a shower that was permitted, inspected and built dry, because a failed or unpermitted conversion is what a buyer’s inspector writes up.
Sources: Massachusetts Residential Code, 10th edition (780 CMR 51.00), Chapter 27 Plumbing Fixtures, sections P2708 and P2709, read 2026-11-12. The plumbing work itself is governed by 248 CMR 10.00, the Massachusetts Uniform State Plumbing Code.
We serve Cape Cod, Massachusetts
Coast Carpentry Home Group works across all 15 Cape Cod towns, from Bourne out to Provincetown. We do not take projects outside the Cape.
On the Cape and looking for an estimate? Call (508) 360-9658 or send us a message.
Thinking about updating your bathroom?
Coast Carpentry Home Group provides bathroom remodeling on Cape Cod. Licensed, insured, and local, with 25+ years of experience. Call (508) 360-9658 for a free estimate.