A bathroom is the hardest-working room in a house and the one most often got wrong. It takes a few litres of warm water several times a day, holds the moisture in the air afterwards, and is usually the smallest space anyone has to plan.
Most of what goes wrong in one is a ventilation problem wearing a disguise. Black grout, peeling paint, a window running with water each morning and a smell that will not shift are all the same story told four ways.
These pages cover the parts worth getting right, in the order they matter: moving the damp air out, laying the room out so it works, keeping water where it belongs, and dealing with surfaces once they have gone wrong.
Bathrooms are expensive rooms to put right, and they hide their problems well. A twenty-minute viewing rarely leaves time to look properly, so it helps to go in with a short list and to look at the things a seller has least reason to point out.
Run everything
Turn on every tap, run the shower for a full minute and flush the toilet. Watch for pressure dropping when two outlets run together, water that takes a long time to warm, and a basin or tray that drains slowly or gurgles. Slow drains are usually a cheap fix; low pressure across the whole house may not be.
Look for old leaks
Check the ceiling directly under the bathroom from the room below. A stain there, or a patch of newer paint on an otherwise tired ceiling, suggests a leak at some point. Press the floor around the toilet and in front of the bath or shower with your heel. Flex, a soft spot or a lifting floor covering means water has reached the boards.
Be wary of anything brand new
Fresh sealant round the bath, a newly painted ceiling or a single replaced row of tiles in an otherwise tired room is not proof of a problem, but it is worth a question. So is a strong smell of air freshener, or a window left wide open on a cold day. A faint musty smell that remains once the room has aired is more telling than anything you can see. In hot, dry places buyers sometimes assume damp cannot be an issue, yet a slow leak behind a shower wall can grow undisturbed for years, and buyers in Arizona are often advised to book a Tucson mold assessment team before exchanging if anything in the bathroom seems off. Anywhere, a specialist inspection costs far less than reopening a finished wall after you move in.
Ventilation and windows
Find the extractor fan, switch it on and hold a sheet of toilet paper near the grille; it should be drawn firmly against it. Check whether the fan vents outside. Look at the window frame and the corners of the ceiling for spotting, which shows how the room has been used.
Ask the right questions
Ask how old the suite and the tiling are, whether there has ever been a leak and how it was repaired, and whether any work was done under a warranty you can inherit. Keep the answers with your survey notes. A clear story and a few receipts are worth almost as much as a perfect room.
Most people look at the walls and the grout when a bathroom starts to look tired. The ceiling gets ignored until the paint above the shower starts to flake, a ring of grey spots appears in one corner, or a brown tide mark spreads out from the light fitting.
Why the ceiling suffers first
Warm, wet air rises. During a shower the ceiling sits in the hottest and most humid layer of the room, and in a bathroom with a loft above it, that ceiling is also the coldest surface for the warm air to meet. Condensation forms there before it forms anywhere else.
Reading the mark
A ring of brown or yellow staining around a light fitting or a pipe usually means water from above: a leaking tank, a weeping fitting in the loft, or a roof problem that has found its way down. That is a plumbing or roofing repair first, and repainting before it is fixed only buys a few weeks.
Black or grey speckling, worst in the corners and directly above the shower, is condensation feeding growth on the surface. Wipe it back with a suitable cleaner, let the ceiling dry fully, then repaint with a moisture-resistant finish.
When the board itself is the problem
If the spotting returns within a fortnight of cleaning, if the ceiling feels soft when pressed, or if paint lifts away in sheets with a damp, dark surface underneath, the growth is no longer sitting on the paint. It has reached the paper face of the plasterboard and often the back of it too. No amount of cleaning will fix a board in that state; it has to come down and be replaced. In very humid climates this happens far faster, and readers in the Gulf states who have written to us about it mostly ended up calling Houston mold abatement contractors to take the ceiling out safely, because cutting out contaminated board spreads spores through the house unless the room is sealed first.
Putting it back properly
A replacement ceiling over a shower deserves moisture-resistant board, joints taped and filled cleanly, and two coats of a proper bathroom paint. The paint matters more than it seems: ordinary matt emulsion absorbs moisture and holds it against the plaster, while a kitchen-and-bathroom paint with a sheen sheds it and gives you a surface you can actually clean. Check that the loft above is insulated right up to the edge of the bathroom, because a cold strip along the ceiling line is where condensation gathers first.
The habits that keep it clean
Run the fan through the shower and for a good while after, crack a window if there is one, and wipe the ceiling above the shower once a month with a long-handled mop. A ceiling that dries out within half an hour of every shower stays clean for years.
A bathroom renovation looks like a list of new things: a shower, a basin, tiles, perhaps a heated rail. What decides whether it lasts is what you find once the old finishes are off, and that is worth planning for before a single tile is chosen.
Take the old tiles off with care
Start at a corner or beside a fitting where a tile edge is exposed, and work along with a bolster and club hammer held low. The aim is to see what the tiles were stuck to, so avoid smashing straight through into the backing. On plasterboard the paper face usually comes away with the adhesive, while solid plaster may release the tiles cleanly or come off in chunks with them.
Read the wall you uncover
The back of the old tiles, and the surface behind them, show how the room has behaved for years. Pale, dry adhesive and firm plaster mean the tiling kept water out. Dark staining along the joints, plasterboard that crumbles under a thumb, or black growth on the back of the tiles mean water has been getting through, usually at the edge of the shower tray, around a tap, or along the bottom row.
Mould that has spread across the face of the board behind the tiles is not a grout problem, and it will not stay put behind new tiling. On a stud wall, test the timbers and the floor beneath with a screwdriver: soft timber is cut out, never sealed in. Where the growth covers more than a small patch, or a musty smell rises from under the floor, the wall needs professional attention before it is boarded again. Renovators in North Carolina often arrange bathroom mold removal in Charlotte before any new board goes up, and the logic holds wherever you live: tiling over contaminated board only hides the trouble for a few more years.
Rebuild with the right board
In the wet zones, replace plasterboard with cement-based or foam tile backer board, screwed at the spacing the manufacturer specifies. Moisture-resistant plasterboard is fine elsewhere in the room but it is not waterproof, so it has no place inside a shower enclosure. Joints and screw heads in the wet area are taped and tanked before any adhesive goes on.
Plan for the air as well as the water
A renovation is the cheapest moment to sort out ventilation. With the ceiling open, a fan can be ducted by the shortest route to the outside, with the duct falling slightly away from the fan so that condensation drains outwards rather than back. Choose a fan sized for the room, wired to keep running after the light goes off, and leave a gap under the door so replacement air can get in.
Keep a record
Photograph the walls before they are closed and note what you found and what you changed. The next person to open that wall, possibly you in fifteen years, will want to know whether it was sound and dry when the new tiles went on.
Taking one bath out and putting another in sounds like the simplest job in a bathroom. In a small room it is usually the one that overruns, because three separate things have to line up at once and only one of them is the bath.
Measure the waste before you measure the bath
The length and width of the new bath matter less than where its waste sits. A bath waste has very little fall to play with, and if the new outlet lands even slightly away from the existing trap position, the pipe either gains a dip that holds water or has to be rerouted under the floor.
Lift a board at the tap end and look. A waste that runs straight into a stack a metre away gives you freedom. One that threads between joists at the far end of the room, at the limit of its fall already, means the new bath's outlet must sit within a few centimetres of the old one. That single measurement decides which baths are actually available to you.
Check the wall while it is open
A bath coming out is the only time you will see that wall. Look at the plaster behind the old one, press the bottom of the studwork if it is a partition, and look along the bottom course of tiles for staining.
Old baths leak slowly at the seal and the evidence collects where nobody can see it. If the plaster is soft, or there is blackness in the corner that wipes off and comes back wet, the moisture has been there a long time and the repair is bigger than the bathroom. Homeowners in that position have been sent towards firms handling bath replacement in Atlanta and equivalents nearer home, and it is money better spent than tiling over soft plaster and discovering it again in two years.
Support it properly
A steel or cast bath wants its own feet bedded on something solid, not on a floating floor. An acrylic bath wants a full timber cradle and, in a small room, a bearer screwed to the wall along its back edge. Fill it and stand in it before the final seal goes on: a bath that flexes under load will tear any sealant you put on it within a few months, and in a small room the flex is harder to spot because the panel hides it.
The order that avoids a second attempt
Rough the waste in, set and level the bath, fit the taps while you can still reach behind them, tile down to the rim rather than to the floor, and seal last of all with the bath filled.
Doing the tiling before the bath is set is the commonest reason a small bathroom ends up with a gap at one end that silicone is asked to bridge. Silicone will bridge perhaps five millimetres and look reasonable. Anything more wants a bath panel and an honest reassessment.
Where it stops being a weekend
Moving the waste more than a short distance, a soil connection, a soft floor near the bath or any smell of damp under the boards are all past DIY. Those are plumbing and building problems that happen to be in a bathroom, and the fitting is the easy part once they are sorted.
Articles