Condensation in deep window reveals

[chuckey]

I have a rock and rubble built cottage, this means that the walls are about 24" thick. The window reveals are splayed to let the light in and suffer from bad condensation at the lower outer corners. I have successfully cured this by stripping the plaster of and fixing on aqua thermal panel with their adhesive. This is a 10mm thick panel material with cementatious outer layers (sorry) with a foam core. Its is very expensive though. If I ever have to re-plaster any room in the cottage I will be installing more of this stuff, it really made a big difference, now the condensation has moved from the reveals to the edge of the wall :-(
Frank

 

[Andrew Bodenham]

Frank,

My house is of similar construction (rubble limestone) and I have experienced a similar condensation pattern.

As windows have been replaced I have undertaken a near-identical modification to that which you describe, except that I have used Marmox board as a cheaper alternative to aquapanel. Marmox has a styrofoam core with fibre-reinforced cement faces, and is available in various thicknesses. It's waterproof, insulating, and rigid. I've fixed it with pU foam and stainless screws. The purists may not like it, but I feel that it's a pragmatic localised solution which works well. Repointing externally around the windows with lime mortar assists with letting these vulnerable areas dry out as much as possible.