How much does it cost to remodel a bathroom?

Everything cheap about a bathroom remodel happens above the slab or the subfloor. Everything expensive happens below it.

Moving the toilet. The closet flange sits over a 3 in drain that runs to a stack, and that drain needs a quarter inch of fall per foot. Move the toilet 4 ft and you are cutting concrete or pulling up subfloor, re-cutting the branch, re-venting, re-pouring, and calling for a rough inspection before anything closes. On a slab that is $1,800 to $4,500 before you have bought a toilet. On a wood floor with a basement below, $900 to $2,000. Leave it where it is and the same fixture costs $350 installed.

Tub to shower conversion. People assume this one is cheap because you are removing something. You are not: a tub drains through a 1.5 in trap set in the joist bay, a shower wants a 2 in drain and a pan that slopes to it, and in most jurisdictions the trade-up triggers the current code for both. Add the waterproofing — a bonded sheet membrane or a liquid over a sloped mud bed — and a curbless entry means notching or dropping joists. Budget $3,500 to $9,000 for the conversion alone, more if you want curbless.

If you keep the fixtures in place and reuse the drains, a gut renovation stays in the low teens. Move both and the same room is a $25,000 job with the same tile in it.

Cosmetic, $3,000 to $7,000. Paint, new vanity and top, new mirror and lighting, new toilet, new trim kits on the existing valve, re-caulk. The tile stays. This is a weekend to five days of work and it is the best return per dollar on this whole page, provided the tile is sound and not the colour of a 1978 avocado.

Mid-range, $9,000 to $18,000. Full tear-out to the studs in the wet areas, new tile floor and shower surround, new tub or shower base in the same footprint, new vanity, toilet, exhaust fan, and a couple of added receptacles. New valve body, same location. This is what most people mean by "remodel".

Full gut, $20,000 to $45,000. Everything above plus the layout moves, the plumbing and electrical are re-run, the window is replaced, and you are likely in permits and inspections for plumbing, electrical and sometimes structure. Custom vanity, slab top, frameless glass, heated floor.

The jump from mid to gut is not driven by material quality. It is driven by how many trades have to come back a second time.

A representative $14,000 mid-range hall bath:

• Labour: $5,600 (40%)
• Tile and setting materials: $1,900
• Vanity, top and sink: $1,400
• Shower or tub, valve and trim: $1,300
• Glass enclosure: $1,100
• Toilet: $400
• Lighting, fan, electrical: $700
• Plumbing rough and fixtures set: $900
• Permits: $250
• Demolition and disposal: $450

The line worth staring at is the first one. Labour is about 40 percent of a bathroom and it does not scale down when you buy cheaper things. A tiler charges the same $12 to $22 per square foot to set a $2 tile as a $9 tile — arguably more for the cheap one, because budget tile has worse thickness tolerance and takes longer to get flat. Halving your material budget on a $14,000 job saves maybe $2,000, not $7,000.

That cuts the other way too, and it is the argument for spending up on the things that are labour-locked. The valve behind the wall, the waterproofing, the exhaust fan ducted to the outside rather than into the attic — replacing any of those later means opening finished tile.

A bathroom is the most fixture-dense room in a house. A 40 sq ft hall bath and a 90 sq ft primary bath both have one toilet, one vanity plumbing group and one wet area, and those are the expensive parts. Doubling the floor adds tile and drywall, which are the cheap parts.

So a primary bath does not cost twice a hall bath because it is twice the size. It costs more because it usually has a double vanity, a separate tub and shower, a slab top, more glass, and more lighting circuits. Take those away and the two rooms are within a few thousand dollars.

The corollary: powder rooms are not cheap per square foot and never will be. A 20 sq ft half bath with a decent vanity, a new toilet, tile and lighting is $2,500 to $5,000, which is $150 per square foot for a room you can touch both walls in.

Spend on the exhaust fan. A 110 CFM unit at 0.3 sones ducted in insulated rigid pipe to a roof or wall cap, on a timer or a humidity switch. It is $250 to $600 installed and it is the difference between a bathroom that stays intact for twenty years and one that grows mould behind the tile. A fan venting into the attic — still common, still failing inspections — is actively destroying the roof deck above it.

Spend on the waterproofing. Sheet membrane or a properly built liquid system, not a plastic sheet stapled behind cement board, and certainly not on green board.

Spend on the valve. A pressure-balancing or thermostatic valve from a brand with parts available in ten years.

Skip the body sprays. They need 8 to 12 gallons per minute to work, most houses cannot supply it, and the ones I have seen installed get used for a month.

Skip the built-in whirlpool tub unless someone genuinely uses it weekly. It is $2,000 to $6,000 that becomes a large plastic shelf, and the pump needs an access panel that somebody has to design around.

Skip heated floors in a room you use for eleven minutes a day, unless you are already tearing up the floor and the incremental cost is under $1,200 — at which point it is one of the nicer things money buys.

A mid-range bath is two to three weeks with a competent GC, and the schedule is nearly all waiting: demo one day, rough plumbing and electrical two days, inspection, insulation and board two days, waterproofing and a cure day, tile three to four days with cure between set and grout, then trim-out. Compress it and the thinset or the grout pays the price.

Permits are usually required the moment plumbing moves or a circuit is added, and run $150 to $600 residential. A remodel done without one surfaces at sale, when the appraiser sees a bathroom the county has no record of.

If it is your only bathroom, price a portable toilet and a shower arrangement into the job or plan to stay elsewhere. Two to three weeks is a long time to be diplomatic with a neighbour.