Bathroom remodel cost, as waterproofing and the stack
Small, dense and unforgiving. Tile is what people photograph. Moving a toilet or a wet wall is what the bid is actually about. Survey $/sf from HomeGuide, then two extras: waterproofing detail and a layout move.
$100–$500per square foot, HomeGuideHomeGuide, “How Much Does a Bathroom Remodel Cost?”, retrieved 23 August 2026 (page dated 20 June 2025). Minor $100–$150/sf, partial $150–$300, full $250–$500. A 35–50 sq ft bathroom is $3,500–$25,000+ on that page.
On the defaults — 40 sq ft, full remodel, layout kept, 15% contingency — the budget is $11,500 to $23,000. That is 40 × $250–$500, plus contingency. Add a move-the-toilet line if the stack is moving; that is plumbing, not tile. Waterproofing of showers and wet areas is a code detail. Ask how it is done before you compare two $/sf figures.
Area, scope, then the stack
Survey $/sf, then extras. Nothing is emailed.
—Budget range
—All-in per sq ft
—Layout
—Waterproofing
What this assumed—
A budget range, never a quote. HyreRemodel does not remodel bathrooms.
A bathroom is not a small kitchen
Kitchens and bathrooms are the two rooms people remodel most, they cost roughly comparable money per square foot, and almost nothing about how they go wrong is the same.
A kitchen is dominated by a single manufactured product — the cabinetry — arriving on a lead time, and its costs are legible: you can point at the boxes and say what they cost. A kitchen that is built badly announces itself. Doors do not line up, the worktop joint is visible, the drawers catch.
A bathroom is dominated by labour and by things you will never see again. The waterproofing behind the tile, the fall on the shower floor, the way the drain connects, the blocking behind the wall for a grab rail somebody may need in twenty years. All of it is buried the moment the tile goes on, and a bathroom that is built badly looks exactly like a bathroom that is built well — for about three years.
That asymmetry should change how you buy one. In a kitchen, comparing quotes on the cabinet specification gets you most of the way. In a bathroom, the specification that matters is the one for the parts that get covered up, and it is the specification most quotes do not contain. A bathroom quote that describes the tile in detail and the waterproofing not at all is describing the part that cannot fail expensively and omitting the part that can.
The failure mode, concretely. Water gets behind a shower that was tiled onto the wrong substrate with no waterproofing membrane. It does that quietly, into the wall cavity and the floor structure, for a long time. What surfaces eventually is a stain on a ceiling below, or a soft spot in a floor, and by then the repair is not the bathroom — it is the bathroom plus the structure under it. That is the risk you are actually managing, and it is why this page spends more words on membranes than on taps.
Where a bathroom budget goes
Labour dominates, and it dominates more than in any other room in the house, because a bathroom packs an extraordinary number of trades into a very small floor area.
Illustrative. Labour, tile setting and waterproofing together are more than half — and all three are skill, not product.
Why labour is so heavy. A forty-square-foot bathroom needs a demolition crew, a plumber twice (rough-in and trim), an electrician twice, a framer or carpenter, a waterproofer, a tile setter, a drywaller, a painter and a glazier for the screen. Ten trade visits into a room the size of a parking space, each with mobilisation time, and several of which cannot start until an inspection has passed. The floor area is small and the coordination is not.
Why tile setting is priced separately from tile. They are different purchases and they are frequently confused. Large-format tile needs a flatter substrate and more setting time. Mosaic has more grout joints and takes longer per square foot. A herringbone or diagonal layout generates far more cuts and waste than a stack bond. The tile you pick changes the labour line as much as it changes the material line, and a quote that gives you a tile allowance without saying which layouts it covers has left that open.
The line that should never be trimmed. Waterproofing is a small share of the total and it is the entire risk. If a budget has to come down, it comes down on fixtures, tile and the vanity — never on the membrane, the substrate or the fall on the floor.
The buried work, and how to ask about it
The buried items below are invisible in a finished bathroom. If a quote does not address them, that is the question to ask — not the price.
Illustrative proportion. The asymmetry is the point: the cheapest tenth of the job carries almost all of the downside.
The buried item
What good looks like
What it costs you if it is wrong
Shower substrate
Cement backer board, a foam board system, or an equivalent — never standard drywall, and never green board, behind tile in a wet area.
Drywall behind shower tile absorbs water, loses strength, and the tile eventually debonds in sheets. It is the classic cheap-build failure and it takes the wall with it.
Waterproofing membrane
A named system — sheet or liquid-applied — installed as a system, with the manufacturer’s own corners, seams and pipe collars. Systems are tested as systems and mixing brands voids the logic of the warranty.
Water in the wall cavity and the floor structure, discovered years later as a stain on a ceiling. The repair is structural, not cosmetic.
Shower floor fall
A consistent slope to the drain across the whole pan, built in the mortar bed rather than hoped for. Water should not stand anywhere when the shower is off.
Standing water, permanent grout discolouration, and a wet area that never fully dries. Not repairable without taking the floor out.
Curb or curbless transition
If curbless, the floor structure has to be recessed or built up to create the fall — that is framing work decided before anything is tiled, not a finish decision.
A curbless shower attempted without the structural allowance either leaks at the threshold or ends up with a lip that defeats the point of it.
Blocking in the walls
Timber blocking behind the finished wall wherever a grab rail, a folding seat, a heavy mirror or a wall-hung basin might ever go.
Costs almost nothing during framing and is impossible to add later without opening the wall. The cheapest piece of futureproofing in the house, and routinely omitted.
Ventilation (2021 International Residential Code, R303.3)
Either a window of not less than 3 sq ft, at least half of it openable, or mechanical extraction at 50 cfm intermittent or 20 cfm continuous.
The fan must exhaust directly to the exterior. Terminating into an attic, crawl space, garage or any other interior space is prohibited — and it is one of the most common defects found in finished bathrooms.
Drainage and the stack
Whether the new fixture positions can reach the existing stack with the required fall, and whether venting is adequate for the new arrangement.
The largest single swing factor in a bathroom budget. Moving a WC in particular can mean opening the floor structure.
The question that decides your budget: does the WC move?
In a kitchen the swing question is whether the sink moves. In a bathroom it is the WC, and for a specific reason.
Every bar above the line is a drainage decision. Fixture choice does not appear because it is not what moves the number.
Why the WC specifically. A basin and a shower drain with relatively small pipe and can often be rerouted within the floor depth. A WC needs a much larger drain, run at a consistent fall, properly vented, back to the stack. In a house with a concrete slab that means cutting and re-pouring the slab. In a house with a timber floor it means working within — or altering — the joist structure, and joists have strict limits on where and how deeply they may be notched or bored (R602 / R502).
The good news. A bathroom that keeps every fixture where it is can be extensively transformed. New tile, new fittings, a new vanity, better lighting, a proper extractor and a glass screen in place of a curtain will read as an entirely new room to anybody who walks into it, and none of it touches the drainage.
When moving it is genuinely worth it. If the layout is the problem — a door that hits the WC, a basin you cannot stand at, a bath nobody has used in a decade occupying a third of the floor — then the layout is the thing to fix, and the money buys you something real. Price it as its own line so the decision is made with the number visible.
The resale note. Zonda’s Cost vs. Value ranking places no bathroom project in its published top ten, and the one interior project that does appear is the cosmetic kitchen. The pattern is consistent across both rooms: cosmetic refreshes of a working layout recoup well, and reconfigurations do not. Remodel a bathroom because you use it every day, not because a table says it pays.
Reading a bathroom quote
Eight checks, weighted toward the parts that get covered up.
The waterproofing system is named
A brand and a system, not "waterproof shower". Ask whether the corners, seams and pipe collars are that manufacturer’s components, because mixed systems are how warranties evaporate.
The substrate behind the tile is named
Cement backer board or a foam board system in wet areas. If the answer is drywall of any colour, that is the answer to your question about this contractor.
It says whether any fixture moves — especially the WC
And, if the WC does move, what happens if the slab or the joists do not cooperate. That contingency belongs in the quote, not in a conversation on the day.
Ventilation is specified with a number
Not "install extractor fan". A cfm rating meeting R303.3 — 50 cfm intermittent or 20 cfm continuous — and an explicit statement that it terminates outside the building.
Blocking is included
Behind any wall-hung fixture, and anywhere a grab rail might reasonably go later. It costs a few dollars of timber now and a wall later.
The tile allowance states the layouts it covers
A per-square-foot allowance that assumed a straight stack bond does not cover the herringbone you chose after signing. Settle the layout before the allowance is set.
The lead-safe position is stated on a pre-1978 house
Under the EPA rule (40 CFR Part 745, Subpart E), a paid firm disturbing painted surfaces in a pre-1978 home must be certified. Bathroom demolition exceeds the 6 sq ft exemption immediately.
The schedule acknowledges the inspection gates
Plumbing and electrical rough-in are inspected before anything is closed up. A schedule that has the tiler arriving the day after the plumber has either allowed for that or is going to be opened up again.
Where to spend and where to save
HyreRemodel view, based on which items are expensive to change later rather than which are expensive now.
Worth the money
Waterproofing and substrate. Ten percent of the budget and effectively all of the catastrophic risk. There is no version of this page that recommends economising here.
The extractor fan. A properly sized, quiet fan, ducted in rigid pipe, terminating outside. A noisy fan does not get used, and an unused fan is a bathroom full of moisture doing slow damage.
The shower valve. Buried in the wall for the life of the bathroom. A good valve from a manufacturer whose cartridges will still be available in fifteen years is worth paying for; the visible trim can be changed at any time.
Blocking, lighting and outlets. All trivially cheap during rough-in and all requiring an opened wall afterwards. Put in more than you think you need.
Where to economise without regret
The vanity. A replaceable piece of furniture that happens to have a basin on it. Changing it in eight years is a morning’s work.
Mirrors, lighting fittings and accessories. Entirely surface, entirely changeable, and where a modest budget goes furthest visually.
Tile, within reason. A well-laid inexpensive tile looks better than a badly-laid expensive one. If the budget is tight, spend on the setter and save on the tile — the reverse is the common and regretted choice.
Keeping and refinishing the existing tub, where it is sound and in the right place. Refinishing has a finite life and it is a legitimate way to defer cost without touching drainage.
The order a bathroom happens in, and where it stalls
Small room, long schedule. Knowing the sequence tells you which silences are normal.
1
Design, and settle the fixture positions
Whether anything moves is decided here, and it is the decision that determines the budget. Changing it after demolition is the single most expensive kind of change order in bathroom work.
2
Order the fixtures and tile — before demolition
A bathroom cannot be paused mid-tile waiting for a delivery, and it is the household’s only bathroom often enough that a stall is genuinely painful. Everything should be on site before anything comes off the wall.
3
Permit, if plumbing or electrical is altered
Almost always required for anything beyond a like-for-like swap.
4
Demolition — with lead containment on a pre-1978 house
Where the surprises live: rot in the floor under the WC, a leak that has been quietly running, or drainage that is not where anyone thought.
5
Framing changes and blocking
Any structural alteration, any recess for a curbless shower, and all the blocking. Last chance to add it for the next thirty years.
6
Plumbing and electrical rough-in — then inspection
A hard gate. Nothing gets covered until it passes, and a schedule that does not allow for the inspector’s availability is a schedule that will slip here.
7
Substrate, then the waterproofing system
The most important day in the project and the one you will never see again. It is entirely reasonable to ask to look at it, or to be sent a photograph, before it is tiled over.
8
Tile — the long, slow part
Setting, then curing, then grouting, then curing again. It cannot be rushed and it is where a small room absorbs a surprising number of days.
9
Fixtures, trim, glass, paint
The glass screen is usually measured only after the tile is finished, which adds a further wait at the very end — the bathroom will look complete and be unusable for a week or two.
10
Final inspection, then the snag list
Walk it, write the list, and hold the final payment until it is closed out.
What this calculator cannot see
What is under the floor. Joist direction, joist condition, whether there is a slab, and where the stack runs. These decide whether moving a fixture is straightforward or structural, and nobody can tell from here.
Existing damage. A bathroom that has been leaking quietly around the WC or the shower base has been damaging the structure below it. That is found at demolition and it is the commonest reason a bathroom budget grows.
Whether it is the only bathroom. Not a cost line, and often the constraint that matters most. A single-bathroom household should plan the schedule around that fact and price the alternative honestly.
Your local labour market. Labour is the largest line here and it varies more by geography than any material does.
Us. HyreRemodel does not remodel bathrooms, does not rank contractors, and holds no dataset of completed projects. Every code figure quoted is from the model code and is subject to whatever your jurisdiction has adopted and amended — check locally before you rely on it.
Questions this calculator answers
How much does a bathroom remodel cost?
HomeGuide’s average is $100 to $500 per square foot, or $3,500 to $25,000+ for a typical 35–50 sq ft bathroom. Full layout changes sit at the top of that band.
Why isn’t tile the driver?
Because waterproofing failure is a tear-out, and moving a toilet is a stack. Both dwarf a $4 tile.
How long does it take?
HomeGuide’s FAQ on the same page: typically 3 to 8 weeks. Open the timeline tool.
Sources and methodology
Figures dated 23 August 2026. Last reviewed .
Bathroom ventilation, IRC R303.3 (2021 model code) (International Code Council (model code), retrieved 2026-09-05. Either a window of not less than 3 sq ft with half openable, or mechanical extraction at 50 cfm intermittent / 20 cfm continuous, exhausted directly outdoors — never into an attic, crawl space or garage. Adoption and amendment are local.)
Renovation, Repair and Painting (RRP) Program (US Environmental Protection Agency, retrieved 2026-09-05. 40 CFR Part 745 Subpart E. Bathroom demolition in a pre-1978 home exceeds the 6 sq ft minor-repair exemption immediately, so the firm must be EPA lead-safe certified.)
How Much Does a Bathroom Remodel Cost? (HomeGuide, retrieved 2026-08-23. $100–$500/sf; minor $3,500–$7,500, partial $5,300–$15,000, full $8,800–$25,000+ for 35–50 sf. Typical duration 3–8 weeks. Member-reported quotes.)