Loft insulation in Victorian and Edwardian terraces

What’s different about these lofts

Many terraces have a loft that is small and low, sometimes shared visually with the neighbours where the party wall stops short of the roof. The ceilings below are often original lath and plaster: thin strips of timber with lime plaster pushed through them. That plaster is held on by its “keys” and can be cracked by heavy weight or someone stepping between the joists.

The roofs were usually built without felt under the slates, so air moves through freely. That actually helps with ventilation, but it also means wind can blow loose insulation around and rain can sometimes get in.

What to ask us

• How will they protect lath-and-plaster ceilings while working?
• Is the party wall complete up to the roof? A gap lets heat and sound pass to next door, and should be fire-stopped; this may be something for a builder.
• Is there old wiring in the loft? Rubber- or fabric-covered cables shouldn’t be buried in insulation and may need an electrician first.
• Is there a redundant water tank that could be removed?
• Which material will they use, and will it let the loft stay breathable?

Rear extensions and back additions

Many terraces have a single- or two-storey back addition with its own small roof, sometimes with no access at all. Ask whether it can be insulated too; it is often a cold spot.