Insulating barn conversions and stone-built properties

Why barns are hard to insulate

Barn conversions and stone-built properties are often complex shapes. There's rarely a straight wall, which makes it hard for traditional insulation to seal properly and avoid cold spots – and these buildings can be very cold if they aren't insulated correctly.

Walls

To insulate barn walls with spray foam, we advise building a timber stud frame inside the property, stood off from the wall by about 50mm. We can then spray directly onto the masonry and between the frame, with the foam lapping behind the studs to reduce cold bridging from the walls. The wall is finished with a vapour control layer before plasterboard – or insulated plasterboard where a lower U-value is needed. Walls below ground level should be protected with a suitable tanking membrane before spraying.

Where the roof meets the wall plate, we spray right up to the top of the wall plate and continue onto the roof, giving a continuous seal from wall to roof.

Roofs

Barn roofs typically have a few large beams and some smaller ones. Clients often like to keep the large beams on show to keep that barn character. The smaller rafters are often only around 70mm deep, so a counter batten is usually fitted to take an adequate depth of foam between them – for example an extra 3×2 batten, allowing around 140mm of foam. Combined with insulated plasterboard over the face, a U-value of around 0.18 is achievable. Changing the depth of the batten and foam, or of the insulated board, changes the overall U-value – we can provide U-value calculations for different scenarios.