How much does a bathroom remodel cost? What sets the number, tier by tier

Ask three contractors to price the same bathroom and you can get three very different numbers, and none of them is necessarily wrong. Bathrooms are the room where the most consequential decisions are invisible: what the fixtures are connected to, what the floor underneath has been doing for forty years, and whether the room has ever been properly ventilated. Tile is the part everyone thinks about and close to the last thing that matters financially.

The three tiers, and where the jump happens

A cosmetic refresh keeps every fixture exactly where it is. You replace the vanity, toilet, lighting, mirror and surfaces, and you paint. Nothing opens up, nothing needs inspecting, and the work is measured in days rather than weeks. A mid-range remodel stays within the existing footprint but goes further: converting a tub to a shower, retiling the wet walls, replacing the extractor fan, sometimes new flooring throughout. Plumbing connections get touched but nothing relocates. A full remodel moves fixtures. That means opening the floor, rerouting drain and supply lines, and bringing everything you touch up to current code. Permits and inspections enter, and the schedule stops being yours. Each tier is roughly double the one before it. The step people consistently underestimate is mid-range to full, because on paper it sounds like a small change — moving the shower two feet — and structurally it is a different project.

What is actually behind the wall

In housing built before 1980 the recurring finds are consistent enough to plan for. Galvanised supply lines well past their service life. Cast-iron waste that is fine until it is not. A subfloor softened around the toilet flange by a leak too slow for anyone to notice. Framing that is wetter than it should be behind a tub surround that was never properly waterproofed. None of these are exotic and none of them are anyone's fault. They are simply what forty or eighty years of use does. What matters is whether your contract anticipates them. A bid with no allowance for concealed conditions on an older bathroom is not a bid — it is an opening position.

Waterproofing is the line item you cannot see

This is where cheap quotes get cheap, and it is worth understanding because you will never be able to inspect it afterwards. A correctly built wet area has a waterproofing membrane — sheet or liquid applied — behind the tile before any tile goes on. It is the only thing between your shower and the framing. Once the tile is up, nobody can tell whether it is there. Omitting it does not produce a problem in year one, or year three. It produces rotten studs and a repeat remodel somewhere around year six or eight. Insist that every quote names the waterproofing system explicitly, and be suspicious of any bid that is materially cheaper and silent on it.

Ventilation is not optional in a damp climate

A surprising number of bathrooms have extractor fans that vent into the attic rather than outdoors, which relocates the moisture problem rather than solving it. Others have fans undersized for the room, or ducted through a run so long and convoluted that airflow is nominal. Getting this right costs modestly and prevents an entire category of problem: mould behind tile, drywall going soft at the surround, and paint that will not hold. If your current bathroom has persistent condensation or a mirror that stays fogged long after a shower, the fan is the first thing to price, not the last.

Small bathrooms cost more per square foot, not less

Homeowners routinely assume a compact bathroom is a cheap bathroom, and the arithmetic does not work that way. Every bathroom needs the same fixtures, the same waterproofing, the same ventilation and the same inspections regardless of floor area — none of those costs scale down with the room. What a small room removes is tile quantity, which is one of the cheaper components. It also adds labour, because working in a two-metre space is slower than working in a generous one. Expect the per-square-foot figure to look alarming and the total to be reasonable.

Decisions worth making before the wall is closed

Blocking in the walls for future grab bars costs almost nothing while the framing is open and a great deal as a retrofit. A curbless shower is far cheaper to build than to convert to. Running a dedicated circuit for a future heated floor is trivial now and disruptive later. None of these need to be used immediately. All of them are decisions that get much more expensive the moment the drywall goes back on, and the omission we hear regretted most often is blocking that would have cost almost nothing at the time.

How to get quotes you can actually compare

Write the scope down before anyone prices it. Specify whether fixtures move, who supplies fixtures and tile, whether waterproofing membrane is included and which system, whether the extractor fan is being replaced and ducted outdoors, and what happens if the subfloor is found rotten. Hand the identical document to each contractor. Without it, three quotes for one bathroom are three different projects, and the cheapest is usually the one that assumed the least.

The contingency, and why it is not pessimism

Hold ten to twenty per cent back for what appears once the walls are open. In anything built before 1980, treat that as likely rather than cautious. The homeowners who finish on budget are not the lucky ones — they are the ones who planned for the thing that turns up, because in an older bathroom something usually does.