Most of these are findable before anyone opens a wall. They become expensive because nobody looked.
1. The grab bars are in drywall anchors
The most common and the most dangerous. A bar screwed into a drywall anchor holds fine when you push on it in the showroom and fails under a 190-pound person going down sideways — which is the only load it exists for.
Bars belong in three-quarter inch plywood blocking behind the tile, installed while the wall is open. Where the wall stays closed, engineered hollow-wall fasteners rated to 800 lb are the accepted alternative. Nothing else.
2. The price moves after demolition
A number given without measuring is a guess, and guesses move. Someone walks the room for ten minutes, writes a figure designed to win the job, and the figure changes once the walls are open.
The things that move it — joist direction, cast iron tub, asbestos, galvanized supply, rotten subfloor — are all findable in ninety minutes with a probe and a flashlight.
3. The door is still too narrow
A beautiful walk-in shower behind a 24 inch door is not accessible if she uses a walker. Nobody asks about the door, so nobody prices it, so it does not get done.
4. The shower floor is the wrong tile
Large-format tile photographs beautifully and is the wrong choice on a shower floor. Not enough grout line to give grip. Look for DCOF 0.42 or higher wet, small format inside the enclosure, or a sealed one-piece base with a certified rating and no grout at all.
5. The valve is wrong, or in the wrong place
A pressure-balancing valve holds pressure but not temperature. A thermostatic valve holds temperature and can be set with a limit stop. For someone with reduced sensation, that is the difference between a shower and a burn she does not feel until afterwards.
And it should be reachable from outside the enclosure, so the water is running before she steps in.
The one nobody tells you about
A slide bar for a handheld shower is not weight bearing. It is not a grab bar and it will not hold a fall. It looks like one, it is at roughly the right height, and people grab it. Every client should be told this in writing.
6. Asbestos found on day two
Ontario Regulation 278/05 puts the obligation on the owner to determine whether asbestos is present before demolition. On a pre-1990 home that means floor tile, mastic and joint compound.
Most contractors never raise it. The crew opens the floor, someone recognises the tile, work stops, and the family is suddenly arranging licensed abatement with the bathroom in pieces.
7. The project runs three weeks and nobody planned the week
The most common reason an accessible bathroom never gets built at all. There is one bathroom, the quote said three weeks, and the family quietly gives up.
Ask how many days, get a number rather than a range, and ask what happens if they run over.
Find the problems before they cost you
The Home Safety Assessment is ninety minutes of measuring the six things that decide the price, with photographs and a lab result. $497, credited in full against your project.