Mold and insulation at top of walls

KayPea

I wonder if any one might recognise this problem and have a solution. Our house is a bungalow and we have lived in it for 2 years. This winter a line of mold has been developing on the top of most exterior walls 18 inches wide. I try to keep it clean but it is an endless task.
There are vents in every room and they are kept open ( only closed at night if temp will go below zero) The house is centrally heated. We have extractor fans in bathrooms.
Someone suggested that the insulation between the layers in our walls stops too low and so the top block has no insulation at all. Could this be the case? If so, how can it be remedied?

Calahonda52

If some of these questions are too techie just give them your best shot.

I presume you mean 18 inches deep, down the wall pretty much all the way around d the perimeter, as opposed to 18 inches wide.

Any chance of posting some pictures?
Any mould on the ceiling?
How old is the house?
Are the eves vented?

The insulation gap is a possibility, as is the less likely option that the wall cavity is not closed on top

The other possibility is that the wall vents are are not ducted from outside to inside, which means that the air gets into the cavity.
Take off an internal wall vet and post some pictures.

All of the above will help the experts who will be along later, I am only keeping the seat warm!

KayPea

Thanks Calahonda,

The house is 7 or so years old but it has been occupied for only 2 years.
The stripe is on the walls only from the ceiling line downwards for about 18 inches.
The eves are vented.
Between the ceiling and the roof space is well insulated with fibreglass, the roof itself is just tile and felt.

The vent covers are nailed to the wall so I haven't prised one off yet. I am waiting for warmer weather to do that. I have tried looking with a torch and I can only see that the hole behind the cover is perfectly circular at both ends so it is likely that there is a pipe or duct.






https://www.facebook.com/kathpeak/media_set?set=a.10211780057993959.1073741868.1144355341&type=3&pnref=story

Calahonda52

Thanks, link broken and pics no show!

Roen

I can see the pics alright. The outside stuff is that red staining you get on walls. I've seen it explained away as a type of mould, a type of fungus, a type of moss and also it being due to the iron content of the sand used when building. Never seen a definitive answer.

Not sure of the exact treatment but it's usually some kind of bleach or acid wash you get in farmers co-ops I recall.

I will say to do your research before treating it though. Opinion seems divided on what will and won't damage your walls while removing it.

Hopefully someone will have an authoritative answer for you soon.

I don't think the red stain is any cause for alarm. It's really only an issue if you find it aesthetically unpleasant.

The houses all around me are full of it. Every second one we viewed when buying had it. Usually seemed to affect gable ends more but could be on all walls.

We are in a coastal region so maybe that's a contributory factor.

As for the interior stuff I'll really leave that to the experts.