Mould/Condensation above skirting

[Anonymous]

Recurrent winter problem: on our living room wall recesses either side of a fireplace we get a (roughly) 6-inch strip of condensation above the skirting which quickly changes to a white mould. This is an external wall on a 1900's (ish) end of terrace with an injection damp course, directly outside is a footpath of stone with little or no mortaring but not connected by mortar or similar to the property. There is little or no draught in the property (double glazed & loft insulation) and we have draught excluding on both external doors. All air bricks are clear of obstruction and we only get this problem when it is cold, rain (& we get plenty in Bolton) does not contribute to the problem. I have had a good look through this site and a couple of others & I think this may simply be down to ventilation, am I correct? And how do start solving this problem?

 

[Anonymous]

It's certainly condensation. You wouldn't get mould growth unless it was fresh water.

It's condensing where it is due to those areas of the wall being colder than the rest. You can either warm those areas up or move the moisture laden air elsewhere.

Matt Green

 

[Anonymous]

sounds like your house is only ventilated by the air brick(s) seeing as you fitted double glazing and blocked all the draughts on your extrernal doors.

How hot do you keep your house (central heating), and maybe if it's a 1900 house you have an open fire/chimney which if lit might help with warmth in this area?

Draughts I thought helped move air around so you didn't get cold patches as such.

 

[Anonymous]

When your Injected DPC was done, did your walls get re-plastered along the bottoms? If so, what was used and how high up?

Where the previous botchers used modern plaster in our house, we get mould - but not on the original lime (fortunately ours never had a DPC treatment).

 

[Anonymous]

You said "Where the previous botchers used modern plaster in our house, we get mould".
Surely you mean "we got mould"?
You've not just left it there, have you?

 

[Anonymous]

There are surface treatments but they don't solve the problem, they just hold back the mould growth for a while.

Increasing ventilation is a must. If you have trickle vents in your windows make sure they are open. If not do you have enough frame space to fit some? or alternatively you could install airbricks into the wall - one at high level and one at low level would be most beneficial.

Also check extract fans in any nearby kitchen, cloakroom and bathroom. Make sure they are working and make sure the timed overun is set to 20 minutes.

 

[Anonymous]

The best way is to not have a cold surface. This is done by dry lining the wall. This can be done very easily - and does not have to extend all the way up the wall. You can maintain breathability of the wall without having condesation through the use of breathable mebranes and thermal insulation.

You can also do this on the outside as well.

 

[Anonymous]

I agree with the alreay recommended remedies belonging to better ventilation. Mostly it's enough 1st to get out the upper rubbers of airtight windows, 2nd better heating. What means permanent heating with even temperature day and night.

So the facade walls will not cool off so much that condensate will come in and it saves energy in spite of otherwise beliefs. But often people let cool off their airtight houses during the night and so mold happens.

Be sure, that there is no mold in your insulation. Normally in such cases there is and later comes allergy and asthma. Be careful with that.

Any insulation at the wall inside or outside will make moldproblems worse. They suck up condensate and will store it, having no capillar activity. Details on the link.



Mould and insulation