chataigner wrote:The rear of the house is a single brick extension - totally uninsulated. The house is already quite small so I'm reluctant to lose 15cm or so to insulation and I'm wondering whether it would be practical to fit exterior insulation under weather boarding. The brick is totally out of character with the rest of the building and those around it, so nothing lost there.
How does one go about that ? Vertical studs the thickness of the insulation, then a membrane, then vertical battens to space the weather boarding away from the insulation ? Is that how it's done ? The insulation would be in direct contact with the wall - I presume that's OK ? I could fit hollow concrete blocks with a dpc on a separate foundation at the base to prevent the insulation and the studs coming into contact with the soil.
Yep, that's all good. Very good. External insulation turns your solid walls into nice big bits of thermal mass. I am about to do something quite similar to my house, but with 2 layers of insulation, not one. The issues with external insulation are at the eaves, gables, and plinth, and around openings. You have the plinth sorted.....now look up. What is the roof overhang like? And at the gable/s? Because the insulation need somewhere to stop, and big overhangs make that easy.