Bathroom design considerations, from the person who has to build it

Design a bathroom in this order: where the plumbing already runs, then the layout, then ventilation and waterproofing, then storage, lighting and finishes. Where the drains and the stack already sit decides which layouts are cheap and which cost you the ceiling in the room below.

Start with where the plumbing already is

In most Toronto houses built before 1940 the main soil stack runs up an interior wall and out through the roof. Every fixture drains toward it and drain pipe has to fall on the way. A fixture near the stack needs a short run and little depth. Move it across the room and it needs more fall, which comes out of the floor structure.

Joist direction decides whether that is possible. Joists parallel to the new drain let it sit in the bay. Joists crossing it limit you, because notching and drilling are capped by code and a pipe that cannot cross means building the floor up or dropping the ceiling below.

What moving a toilet costs

The toilet drain is the biggest pipe in the room and needs the most fall. Moving it inside the same joist bay is usually manageable. Moving it across the room usually means opening the ceiling underneath, which turns a one-room renovation into a two-room one, with drywall and paint downstairs and another inspection.

In many small bathrooms, leaving the toilet in place and rearranging the sink and shower gets most of the improvement for far less disruption.

Walk in shower vs tub

Keep a tub if you have small children or if it is the last full bathroom in the house. Family buyers in Toronto still expect a tub somewhere and taking out the last one is hard to undo.

Go with a walk-in shower in an ensuite or a second bathroom or a main bathroom where nobody has taken a bath in five years. It makes a small room read larger and it is far easier to get into at 70. A straight swap in the same footprint is the easy version: the drain is in place and the walls stay put.

Small bathroom design and where to steal space

Most small bathroom problems are storage problems wearing a layout problem's clothes. Before you move a wall, look at where space is already sitting.

• The hallway linen closet backing onto the bathroom, which often buys depth for a proper shower.

• The hallway itself. Borrowing a foot from a wide hall changes a bathroom and nobody notices.

• Over a stair run, for a bench or a niche.

• Interior stud walls, for a recessed medicine cabinet and niches planned before rough-in.

Do not recess into an exterior wall in a Toronto brick house. There is rarely depth and where there is, you are removing insulation from the coldest wall in the room.

Ventilation and waterproofing are design decisions

Mould in a Toronto bathroom is almost always one of these two done badly.

The fan. Size it to the room and then to the duct run, because elbows and long runs cut real airflow well below the number on the box. Duct it outside, to an exterior hood with a working damper. A fan dumping into an attic or a soffit puts every shower back into your roof structure and over a Toronto winter that condenses and stains ceilings. Harvey is a certified Passive House Tradesperson: formal training in insulation, air sealing and ventilation.

The waterproofing. Cement board is water-resistant backing. Waterproofing goes on top: a bonded membrane, sealed corners, a sloped base under the tile, a bonded drain and one manufacturer throughout so the warranty holds. Ask for a flood test of the pan before tile goes down. This line never gets trimmed. A pan that fails takes out the subfloor and the ceiling below, along with the tile you just paid for.

Heated floors while the floor is open

An electric mat goes under the tile on its own circuit with a floor sensor. With the room already down to the subfloor it is a small addition and retrofitting later means the tile comes off. Over an unheated basement or a cold porch it decides whether the room is usable in February.

Storage, lighting and tile

Storage. Drawers beat doors: a drawer uses the full depth of the vanity, a shelf behind a door uses the front half. Ask for the top drawer to be notched around the trap so you keep it. A wall-hung vanity reads larger and needs blocking in the wall before drywall goes on.

Lighting. An overhead fixture alone puts your face in shadow at the mirror. Light it from both sides at about face height and put a sealed wet-rated fixture in the shower. Give the fan its own switch. Eyes at 65 need more light than eyes at 40.

Tile. Porcelain with a matte or textured surface, rated for wet floors. Small format on a shower floor gives more grout lines and better grip underfoot. Large format on walls means fewer grout lines to scrub and on a century floor it needs a flat substrate.

Build the accessibility in now

Most people renovating a bathroom in their forties or fifties are staying in the house. These cost little now and a lot later.

• Blocking. Plywood behind the drywall beside the toilet and in the shower, at grab bar height.

• A curbless shower. The subfloor gets dropped so the floor drains without a lip.

• A comfort height toilet, which sits at chair height.

• A wider door, swinging out or sliding, so the clear opening takes a walker.

Where to spend and where to stop

Spend on what you cannot change later: the waterproofing system, the fan and its duct, the mixing valve behind the wall, plywood vanity boxes and floor tile you will not slip on. Quartz holds up on a family bathroom counter; marble etches permanently.

Spend less on what you can swap in an afternoon: the toilet, the mirror, the light fixtures, the hardware. Think twice about honed marble floors and vessel sinks that splash.

Have it looked at before you draw it

Harvey will find the stack and the joist direction and tell you what that leaves you for a layout. We produce 3D renderings for bathrooms during design, so you see the room before it is framed. Get a free consultation or call Harvey at (416) 489-4083. See our Toronto bathroom renovation page and the photo gallery.

Frequently asked questions

What should I consider first when designing a bathroom?

Where the stack and the drains already run and which way the floor joists go. Those two facts decide which layouts are cheap and which need the ceiling below opened.

Walk in shower vs tub, which should I choose?

Keep a tub if you have small children or if it is the last one in the house, because most family buyers expect one somewhere. Go with a walk-in shower in an ensuite, a second bathroom or where the tub goes unused.

How do I make a small bathroom work?

Solve storage before moving walls. Take space from a hallway linen closet or an interior stud wall and use drawers in a wall-hung vanity.

Does a bathroom fan have to vent outside?

Yes. A fan ducted into an attic or a soffit puts shower moisture into your roof structure and in a Toronto winter that condenses and stains ceilings below.

Should I plan for aging in place now?

Yes, if you intend to stay. Blocking for grab bars, a curbless shower, a comfort height toilet and a wider door cost little while the walls are open and a lot once the room is tiled.