Work out where you can actually stand

Loft bathrooms are shaped by the roof, not by a neat rectangle on a plan. Before you choose a single fitting, mark out the head-height zone: the band of floor where the ceiling is tall enough for an adult to stand and turn around. In most UK loft conversions that is the strip under the ridge, and it is usually narrower than people expect. Anything below about 1.4 metres is storage and skirting, not standing room.

Draw the floor to scale and note the ceiling height every 300mm across the width. Then place the room around that tall strip: the basin at the low eaves end where you only ever bend forward, the shower under the ridge or in a dormer, the WC where a seated person's knees will not meet a slope. Door swing matters too. If the door opens against the basin, you will feel the squeeze every single time you walk in, however clever the tiles are.

Wall-hung fittings buy you floor

Nothing opens up a small room faster than visible floor. Floor-standing vanity units and back-to-wall WCs sit on the ground and draw a heavy line across the tightest part of the space.

• Choose a wall-hung WC on a concealed frame. In a loft you can often build the frame into a boxed section over the eaves or a stud wall, so you lose no more depth than a standard close-coupled pan.
• Specify a wall-hung basin or a shallow vanity around 350–400mm deep, rather than the 500mm-plus units sold for family bathrooms.
• Fit a low-profile shower tray or, where the joists allow after a structural check, a flush-to-floor former so there is no step to catch your eye.
• Use wall-mounted brassware and a fixed shower head instead of a bulky riser rail and exposed pipework.

Every one of these choices removes something from the floor plane, and the eye reads the room as larger even though the dimensions have not changed.

Go large with tiles and quiet with grout

Small tiles create a busy grid of lines, and in a room three metres long that grid is the first thing you see. Large-format tiles, whether 600 x 300mm or 900 x 450mm, cut the number of joints dramatically and let the surfaces read as continuous planes.

Stack them vertically on the walls to draw the eye upwards, which flatters a low ceiling, and avoid feature borders and mosaic bands that chop the walls into horizontal slices. Match the grout to the tile shade so the joints almost disappear. If you want a single material to do the work, run the same tile from floor to wall in the shower and behind the basin, and keep the palette to two or three tones at most.

Bear in mind that large porcelain tiles are heavy. Loft floors are often formed from timber joists with a limited span, so ask your builder to confirm the loading and to tank the wet areas properly before tiling.

Let a rooflight do the heavy lifting

A vertical window in a dormer is lovely, but it takes wall space you may not have. A rooflight set into the slope gives you daylight without sacrificing a single centimetre of usable wall, and it does something a wall window cannot: it brings light down from above, softening the corners of the room.

Position one over the shower or basin so the space you use most is the brightest. A sun tunnel can reach an awkward pocket where a full rooflight will not fit. Place the mirror opposite the light source and it will bounce daylight back into the room.

Daylight is not ventilation, though. Building Regulations require mechanical extract in a bathroom without a openable window, and even with one an extractor fan with a humidistat and overrun timer is worth having. A slim inline fan ducted through the roof slope keeps the ceiling clear of bulky units.

Hide the clutter in the slopes

The low, awkward zones under the eaves are storage gold. Build shallow cupboards along the sloping side for towels, spare loo roll and cleaning supplies, with doors finished in the same colour as the walls so the run disappears.

• Recess a niche into the wall beside the shower instead of hanging a wire caddy.
• Choose a slim mirror cabinet, or recess one into a stud wall so only the door sits proud.
• Use the space behind the door for a tall, shallow shelving unit, no more than 200mm deep.
• Keep the counter clear with wall-mounted hooks and a closed drawer for the hairdryer and straighteners.

Clutter is what makes a small room feel small. A clear surface is worth more than an extra metre of floor.

Finish it so the eye has nothing to trip over

Paint the sloped ceiling the same colour as the walls, or the same soft white throughout, so the room reads as one volume rather than a box with a lid. Keep the flooring continuous with the landing where you can, which makes the threshold less of a stop line.

Stick to a single metal finish for taps, shower and towel rail — a vertical ladder radiator takes far less wall than a chunky horizontal one. Layer the lighting instead of relying on one central bulb: a wall light beside the mirror, an IP-rated fitting over the shower, and a warm dimmable circuit for evenings. Add a demisting mirror pad and you will never wipe the glass again.

None of these ideas are expensive on their own. Together they turn a tight, sloping attic corner into a bathroom that feels calm, bright and, crucially, easy to move around in.