Black mold spots - above shower ceiling

[utterlydiy]

Since having a shower fitted in the corner of the bathroom 6 years ago against an inner wall, we have experienced Black mold spots on the ceiling above the shower.

I've kept this under control by cleaning with bleach every month, but only in the Autumn/Spring months and leaving the window ajar and bathroom door open to allow to vent the bathroom after a shower. Summer it is OK with no problems.

Some 5 years ago, we had new loft Insulation (8") on top of the older 2" layer.

Being the roof slopes steeply closely near the outer part of the bathroom and although the insulation now being 10", I thought if being so close to the roof and this being a cold trap as this only occurs in the colder damp months.

I went up into the loft and found the area above the mold spots was not fully covered by any insulation and that the plastic membrane of the plaster board was damp/wet with condensation.

Found a spare roll left by the installers and covered the area with 8" of insulation.

Now my question is, would this cure the problem or should I fit a extractor fan above.

Any advice please. Thanks

 

[Grenage]

Fit an extractor fan, and consider a repaint with something like Zinnser perma-white. Make sure there are no holes in the bathroom ceiling, which would allow moist air to enter.

 

[AronSearle]

It will certainly improve it.

not sure it will stop it, try it and see = asking if you should fit an extractor fan assumes you don't have one. Windows can provide enough ventillation, but not always and it depends on how long they are open for.

 

[utterlydiy]

Thanks for the replies.

I've always thought that with such as this, if you have warm moist air on one side and where the insulation material was missing a cold damp air on the other was the breeding of mold on the warm side.

With the window, it is ajar all day and closed at night with a trickle vent open. But the door is always open.

I'll give a repaint with something like Zinnser perma-white a try.

thanks

 

[JohnD]

are you rejecting the extractor fan?

 

[utterlydiy]

Not entirely.

But thought I'd try the normal traditional methods first.

Like reading a Paper road map before going to a SatNav.

But this area above the shower is the only area with the mold and where the insulation was missing, meaning all the ceiling and walls are covered with condensation after a shower and no mold is seen elsewhere.

thanks

 

[JohnD]

if you have room above the ceiling, you could fit a ducted inline fan, which can be three times as powerful as a typical cheap builders fan, and quieter.

 

[Flyboytim]

You are using too dilute bleach, and probably washing it off after a short time. This is not biocidal, just cosmetic, and the mould will regrow in a short time. It's like putting a dash of bleach in the loo and then flushing it away after a couple of minutes, where the instructions recommend an overnight soak.

Use neat thick bleach, painted on with a nylon (not bristle) paintbrush, do not scrub. Allow to sink in/dry onto the ceiling/walls/grout. Hidden sources of mould spores are the rubber seals around the glass in UPVC windows, and the hidden surfaces of the window when closed.

The bleach will remove all visible traces of the mould, in all cases except when the mould has penetrated deep into silicone sealant (which will need to be removed and replaced).

Ventilate during application and until the bleach is dry.

This will destroy mould and spores and leave an organochlorine residue on the surface which will deter regrowth. It will not damage painted, plastered, or tiled surfaces. You should not need to reapply more often than twice during a very damp year, like the last one.

The problem with powerful ventilation extractor fans is that the extracted air has to be replaced with air, usually from other parts of the house - which is heated, and contains a significant quantity of moisture.

Save on your energy bills - wipe down all surfaces post shower with a squeegee and cloth that has had bathroom cleaner sprayed onto it to remove the bulk of the water, limescale and soap or shampoo residues which act as a substrate for microbial growth, and to ventilate directly with an open bathroom window, where possible, with the bathroom door shut. Don't overheat the shower room, it will warm rapidly due to the shower itself.

Leaving a window ajar will exaggerate the thermal gradient in the room - which will lead to greater condensation on cold surfaces when the shower is used.

Instead, leave the room shut and warm when surface moisture has dried, and only ventilate for as long as required.

I cannot comment on all damp-proofing paints, but most applications I've ever seen peel off or crack the emulsion beneath and look awful. Probably due to poor preparation or application on already mouldy or damp surfaces, I'd guess. I'd avoid them.

 

[utterlydiy]

Thanks flyboytim,

Everything you suggest is done as for cleaning etc. and the shower cubicle and walls are wiped after a shower.

The mold is only is only above the cubicle of approx. 8 spots/dots. It is not found/seen elsewhere in the bathroom.

The window and door is left ajar to vent/dry the bathroom quicker, which it does otherwise the damp/condensation hangs around for a longer time.

thank you anyway.