A bloke at Thirroul had his bathroom ceiling painted three times in five years. Three different painters, same ceiling, and every winter the dark patches came back through in the corner above the shower. By the time he rang me he had decided the problem was the paint and wanted to know which brand to use.
I held a square of toilet paper flat against the exhaust fan grille and let go. It fell straight to the floor. The fan was running. It had been running for five years and moving next to nothing.
That is most bathroom paint failures I get called to. The paint is the symptom.
Start with the fan, not the tin
The toilet paper test settles the argument before anyone opens a can. Fan on, single square held flat against the grille, let go. If it sticks there, the fan is pulling. If it drifts down, you have an ornament in your ceiling that makes a noise.
Fans die quietly. The motor keeps humming, the housing looks the same as the day it went in, and the airflow drops off over years without anyone noticing, because the thing you notice is the noise and the noise never stopped.
The other half of it is where the fan sends the air. Plenty of the ones I look at in older houses through the Illawarra discharge straight into the roof cavity. The steam leaves the bathroom, which is why the mirror clears and everyone assumes it is working, and then it condenses on the cold underside of the roof and finds its way back down through the ceiling. You end up with a moisture problem in two rooms instead of one.
The Australian Government's Your Home guide gives the rule in one line: vent bathroom, laundry and kitchen exhaust directly outdoors. Not into the roof space, not into the eaves lining, outside.
Worth saying plainly: fan work is not ours. Replacing a fan, moving one, or running a new duct and switch is electrical work, and in NSW that needs a licensed electrician with no dollar threshold anywhere in the conversation. What I can tell you is whether the fan you have is the reason your paint keeps letting go, because that costs nothing to find out and it changes what you do next.
Painting over mould does not kill it
NSW Health is direct about the mechanism. Mould needs moisture and nutrients to grow, and the practical advice on that page is to run the exhaust fan while showering, open the window when the weather allows, and fix the water getting in.
None of that is about paint, which is the point. Mould in a bathroom is feeding on soap film, skin, dust and whatever else settles on a wet surface. Rolling a fresh coat over the top buries the growth without removing the food or the water, and it comes back through as shadowing inside a year or two. Same thing happens on the outside of a house, which is the wash before painting post, except an exterior wall gets rain and sun and a bathroom gets neither.
So it comes off before anything goes on. Wash it down, let the surface dry properly, and give it a day if the weather is against you. Cleaning a mouldy ceiling is a miserable hour and it is the hour that decides whether you are doing this again.
Mould-resistant paint is real and oversold
It works the way it says on the tin, which is less than people hope. There is a fungicide in the film that slows regrowth on the surface of the paint. It does nothing about the water behind it, under it, or dripping onto it.
I use it in bathrooms. I also tell people it buys a season, not a decade, if the moisture problem is still live. Paying extra for the mould-resistant version and skipping the fan is spending money in the wrong order.
Sheen matters more than most people expect and gets less attention. A low-sheen or satin acrylic wipes down, sheds water and stays put. Flat ceiling white in a bathroom looks beautiful for about a year and then holds every mark and every bit of moisture that touches it. If the ceiling has failed before, that is the first spec I change.
The prep is the whole job
Peeling is an adhesion failure, and it is nearly always the same picture underneath. I scrape back and the old film is still glossy on the reverse. Nothing ever bonded to it. Somebody rolled a coat straight onto a surface that had a soap residue on it and the paint has been hanging on by nothing since the day it dried.
Bathrooms carry a film that other rooms do not, and it needs washing off with sugar soap before a sander goes anywhere near. After that it is scraping back to sound edges, sanding the gloss off so the new coat has something to key into, feathering the edges of the scraped areas so you cannot read them through the finish, and spot-priming anything that has gone back to bare plasterboard. Patch where the paper face has lifted. Then, and this is the one everyone skips, let the room be dry when you paint it. Painting a bathroom on the same day somebody showered in it is starting the job at a disadvantage for no reason.
That sequence is the same one on the painting page for every other room in the house. Bathrooms just punish you faster for skipping it.
When it is not the paint at all
If the mould sits in one corner, or the ceiling is bubbling in one patch while the rest is fine, stop treating it as a paint job. Localised damage means water arriving from somewhere specific.
A shower that has lost its waterproofing wets the wall from behind, and there is no coating you can apply to the front of a wall that fixes water coming through the back of it. Knuckle the tiles in the shower and listen for the hollow ones, look at the state of the silicone in the internal corners, and check whether the grout has cracked in a line rather than crumbling generally. The regrout or retile post walks through what each of those means, and bathroom tiling covers the repair end of it.
If it turns out to be a tap, a pipe or a waste, that is a licensed plumber and it is not a small job pretending to be a big one, it is the opposite.
The order that works: prove the fan moves air, find and stop any water, clean the mould off properly, prep like you mean it, then paint. Paint goes last every time. If you want a second opinion before you buy anything, send us photos of the ceiling, the corner where it comes back, and the fan grille, and we will tell you which of those five steps you are actually stuck on.
Want a hand with this at your place? Get a free quote or call 0450 959 936.