Why does mould keep growing on my ceiling and how to stop it?

I am often asked,”how can insulation stop mould?”, well mould needs heat and moisture to grow, that is why you will notice that your mould problem is worse in summer than in winter.

When will insulation help to stop mould forming on your ceiling, If the mould is associated with a very small area it is more likely that it is related to a roof leak above that area. If it can be stoped by insulating your home then it will almost certainly have patterns left by the timber structure above the ceiling.

So a simple proof that ceiling insulation will help is that you will often see patterns through the mould on the ceiling where it is obvious that there is timber above these areas. This is where the heat can not get to the ceiling as the roof timbers are stopping it. This proves that insulating your ceiling will stop the mould from coming back after it is removed and after your insulation is removed. So insulate your ceiling and clean the existing mould off for the last time!

Many customers think that the mould on the ceiling is something to do with moisture in the roof space but this is just wrong. Your roof space is very hot during the day (even in winter) and there is no chance of moisture coming though your ceiling to cause mould without your having an actual water stain on the plaster where a roof leak is wetting the area.

Just the normal moisture in the air in your roof crawl space is never going to cause mould on your internal ceiling but sales people who sell expensive roof cavity ventilators will not tell you that. Roof vents are not a solution for mould in most cases and will actually cause more problems for you over time as they often leak and are the first thing to be damaged in a storm.

Of course if insulation does not stop the mould then you will need additional ventilation to move stale, damp air out of the internal space of your home but insulation is normally the first and biggest part of the solution to mould problems on ceilings in Queensland.

If you install cellulose fibre insulation it will be more effective at stopping mould just because it stops more heat than batts do as it is pumped in. Mainly because it is pumped in and has no gaps but batts are very hard to install with no gaps. The other reason it is better for stopping mould is because the borax in the product is actually a natural fungicide and kills any mould it contacts. Of course it will not contact the mould on the inside of your ceiling but it will contact any existing mould up in your roof space and kill it. Borax is also a natural disinfectant and so your roof is left smelling a lot cleaner and without any mouldy smells it might have had before.