Are air bricks the answer.

[mum3kids]

Hoping someone can help,

I have a back extension off the kitchen, walls are painted but every winter along the bottom of the largest wall I get black damp, it's not coming from outside, it seems just to be the condenstation from the kitchen. As much as I keep cleaning it off, it's back within a few weeks and is driving me MAD.! I have an extractor fan going when cooking but that doen't seem to make any difference.

Is it a ventalation problem, Would putting in air bricks stop the black stuff from forming?

Thanks

 

[DAZB]

You don't mention if you have any heating in that area but it would help. It is a combination of heating and ventilation that helps combat condensation.

 

[mum3kids]

You don't mention if you have any heating in that area but it would help. It is a combination of heating and ventilation that helps combat condensation.

Yes I have a double radiator on another wall which is always on, it's a large room about 13ftx12ft.

 

[Alastairreid]

does your extractor vent to outside? or does it recirculate.

 

[^woody^]

Is this a solid or cavity wall?

 

[mum3kids]

does your extractor vent to outside? or does it recirculate.

The extractor in the kitchen vents outside, I also open kitchen window when cooking.

Is this a solid or cavity wall?

The wall is a cavity wall, not filled with any cavity insulation.

 

[^woody^]

It seems to be condensation related and there are the usual things to check- hating, ventilation, air flow etc.

But persistent mould in a location like that may relate to a cold bridge of the cavity where rubble or mortar is in the cavity - and whilst not causing damp to come in or up, it does cause the wall to be colder at the bottom, thus allowing condensation to form there.

For the mould treatment, don't just wipe it off or use a bleach. Use a proper fungicidal wash and then paint with a specific "kitchen and bathroom" emulsion which will inhibit future mould growth

 

[mum3kids]

It seems to be condensation related and there are the usual things to check- hating, ventilation, air flow etc.

But persistent mould in a location like that may relate to a cold bridge of the cavity where rubble or mortar is in the cavity - and whilst not causing damp to come in or up, it does cause the wall to be colder at the bottom, thus allowing condensation to form there.

For the mould treatment, don't just wipe it off or use a bleach. Use a proper fungicidal wash and then paint with a specific "kitchen and bathroom" emulsion which will inhibit future mould growth

Thanks very much for the advice, yes the wall does always feel alot colder along the bottom I did wonder why that was!.

I will do as you suggest and hope that cures it.

Many Thanks.

 

[gday2uk]

But persistent mould in a location like that may relate to a cold bridge of the cavity where rubble or mortar is in the cavity - and whilst not causing damp to come in or up, it does cause the wall to be colder at the bottom, thus allowing condensation to form there.

If the cavity is blocked above and below dpc level then surely moisture could transmit from one skin to the other causing penetrating damp?

 

[^woody^]

Not always.

The wall may not get wet enough to start with, and even it is did so, there may not be enough moisture to travel the 250mm to the inside before it is naturally evaporated or diffused

Condensation dampness, and not penetrating or rising dampness, is still the most prevalent form of dampness in solid walls

 

[gday2uk]

Not always.

The wall may not get wet enough to start with, and even it is did so, there may not be enough moisture to travel the 250mm to the inside before it is naturally evaporated or diffused

Condensation dampness, and not penetrating or rising dampness, is still the most prevalent form of dampness in solid walls

Agreed, but you can't rule it out

 

[^woody^]

No, you can't, but the signs will be different of moisture ingress is occuring

 

[JohnD]

//www.diynot.com/wiki/building:condensation_in_houses