Once a wall/ceiling is mouldy, can you really treat it?

[MisterBoy]

We have quite bad black mould on the walls of our bathroom (solid brick walls) that has slowly got worse despite a trickle ventilation fan (and a very draughty sash window!) and it has now spread to the ceiling.

We periodically wipe the walls but the ceiling is artex or similar textured finish so can't easily remove it physically.

Long-term we want to renovate the room and insulate but for now it's causing an issue as it's ugly and my wife has asthma. The discussion we've been having is whether painting it with anything actually kills the mould or if it's engrained in the plaster and, whether we can see it or not, the spores are still there no matter what treatments we use.

Is it worth using anti-fungal paint in the short term? The current paint needs re-doing anyway, it does't really seem like it's good scrubbable bathroom paint.

 

[foxhole]

Trickle ventilation is ineffective, Needs powerful fan and draughty windows make the room cooler increasing condensation .
You can spray ceiling with mild bleach mix but needs face protection to use.

 

[MisterBoy]

Well it's a trickle fan that has manual boost and automatically boosts when it detects high humidity but I don't think anything will prevent condensation from a hot bath in a room with 3 exterior walls!

So we clean all surfaces as thoroughly as possible, then treat with bleach or similar, then repaint with anti-mould paint (or paint + additive)?

Some paint is starting to peel, I guess we'd scrape and patch but would that be better before or after bleaching (I think I prefer an anti-mould spray for preference) - thinking scrape first and then the bleach will be getting into the remaining surface better?

 

[opps]

If the paint is peeling, it sounds like it is regular emulsion.

It also suggests that the ventilation is insufficient. You mention that you have a humidistat fan. After showering, leave the door slightly open to allow the air to be sucked out

Go with bleach or a dedicated spray to remove the mold.

Remove the flaking paint. Back fill to feather it, then prime with a water based primer or dilute emulsion, then apply two coats of waterbased eggshell.

I have decorated numerous shower rooms for customers over the years. Waterbased eggshell works very well.

In rooms with insufficient ventilation, the moisture will settle on the ceiling but it will not penetrate through the paint.

Down side= water will pool on the ceiling and may drop down to the floor.

 

[MisterBoy]

Cheers (to both)... I'm not sure if it's regular paint, or just been painted a long time. It may even be the peeling areas are due to external damp - the house was repainted last year and the inside of this wall was already looking pretty tired. Either way the outside wall is now sorted and this paint is at least 7 years old.

Yeah, we plan to use eggshell or some other similar product, we have great success with scrubbable paint in a semi-commercial kitchen which is washed daily (I think it is an eggshell).
In which case we might add an anti-mould additive instead of just using anti-mould paint, as it gives us more flexibility to use the paint we want.

 

[foxhole]

Humidity stats tend to be very poor as by the time they’re triggered You already have condensation in the room so it’s too late for the fan to do anything.

 

[MisterBoy]

Humidity stats tend to be very poor as by the time they’re triggered You already have condensation in the room so it’s too late for the fan to do anything.

We have a couple - the one in the ensuite turns on within a minute of the shower turning on, the one in the main bathroom frequently turns on before the bath finishes running. Though it depends on the weather, sometimes it doesn't. The bigger issue is I don't like it running while I'm in the bath (I like the peace) and then have to remember to trigger it after. This is probably the main issue, not an issue with the fan - it's a Greenwood 2CV or something like that... we really like them.

 

[foxhole]

We have a couple - the one in the ensuite turns on within a minute of the shower turning on, the one in the main bathroom frequently turns on before the bath finishes running. Though it depends on the weather, sometimes it doesn't. The bigger issue is I don't like it running while I'm in the bath (I like the peace) and then have to remember to trigger it after. This is probably the main issue, not an issue with the fan - it's a Greenwood 2CV or something like that... we really like them.

So that’s the problem both should be running before any moisture is produced and not be turned off .

 

[bsr]

Zinsser permawhite is guaranteed mould free for seven years. Comes in a Matt white finish and can be tinted for walls.

Long term agreed you will need to go back to bare brick and insulate internally. I think something like 50mm insulated plasterboard would make a massive difference.

 

[MisterBoy]

Zinsser permawhite is guaranteed mould free for seven years. Comes in a Matt white finish and can be tinted for walls.

Long term agreed you will need to go back to bare brick and insulate internally. I think something like 50mm insulated plasterboard would make a massive difference.

I think I bought some of that last spring and never got round to it - but I do like the idea of a more scrubbable waterproof paint.

Speaking of long-term... is it important to rip off the plaster, tiles etc or can you just hide it all behind a stud? We've all seen that the latter IS done quite often when we've found questionable wallpaper, etc but is that a really bad idea?

 

[opps]

Humidity stats tend to be very poor as by the time they’re triggered You already have condensation in the room so it’s too late for the fan to do anything.

Our Manrose is pretty sensitive.

If I start running a bath, it will turn on after a minutes. Long before there is any noticeable condensation.

The mirror on the wall does occasionally steam up but I suspect that is the result of a lack of airflow entering under the room door.

On very humid days, it will kick in even when the bathroom isn't being used.

 

[MisterBoy]

On very humid days, it will kick in even when the bathroom isn't being used.

We get the same. Sometimes it will just turn on for hours...

 

[Diver Fred]

Ventilation is the key. A Dehumidifier will also help but does need running for extended periods - so it's a cost to benefit decision.

 

[opps]

We get the same. Sometimes it will just turn on for hours...

I have fitted other brands for customers that would occasionally turn on when it rained in the summer.