Lime plaster on brick

[Michelle73]

Hi everyone,
Maybe a silly question but going to jump in and ask anyway.
I have an old single storey extension tagged onto the back of our stone built terrace. The extension, is built of single skin brick which is harled on the outside and painted with a weather proof paint.
The inside gets extremely cold and condensation from the kitchen builds up on the interior walls. We've spent some time fixing the roof and guttering and have just taken down the rotten plasterboard ceiling which will be replaced and insulated. The floor is concrete.
Would lime plastering the internal walls give much benefit in the way of retaining heat and dealing with the moisture?
If so can the lime plaster be applied directly to the brick or would we need to fix it to a lath? The room isn't very big so need a solution that doesn't eat up too much of the space. We also want to be able to do the work ourselves. A local company recently quoted 6.5k + vat :shock:

Thanks in advance for keeping me on the straight an narrow!

 

[MdB]

This is what I think though as I am new to this, don't act on any of this until someone with more knowledge has confirmed it.

You are getting condensation due to warm moist air hitting a cold surface. You can reduce this by ventilation (extractor fan in kitchen etc) to help remove the moisture or by warming the wall so that it doesn't cool when it hits it.

Insulation on the outside of the wall will help a bit as it will raise the inside wall temperature. However, it won't reach the temperature of the moist air due to its bulk so it won't be the best solution. Insulation on the inside of the wall with a thin surface layer will allow the surface to quickly rise to the temperature of the moist air as it has little bulk. As the air will only be cooled a little when it hits the wall, condensation will be greatly reduced.

Lime plaster directly onto brick work is not a problem as long as the wall is damped first, however this will give you little insulation and would make little difference to the condensation. A layer of insulation, a vapour barrier and then plaster board would be a lot better. Laths + lime instead of plaster board would also work but wouldn't be as cheap and I don't really see the point in a modern extension.

 

[NT]

Agreed, you want insulation rather than plaster. A dehumidifier is an option, but would not give the bvenefit of insulation. I wouldnt use a fan, total cost is well above a dehumidifier.

NT