retrofit insulation to loft conversion

John_Coyne

A loft room was created in a roof space some years ago, but the builder left the plasterboard walls uninsulated.
I have access to the back of the walls and want to put insulation between the vertical wall battens.
I thought something that was easy to cut to size and attach would be good. I've heard that Kingspan can de-laminate when cut by an amateur. Maybe Celotex is easier to cut??
Or should I be trying for a loose insulation material to put behind plywood or netting?

And do I need a moisture barrier? Annoyingly, the electrical wires in the residual roof void interpenetrate the space between the battens, so it's going to be hard to create a continuous membrane.

missile

I've heard that Kingspan can de-laminate when cut by an amateur.

I saw some builders using insulation board for a conversion and they used hand tools to cut to shape, so I doubt that would be an issue.

I would not bother with a moisture barrier but if you think it necessary, foil backed may be suitable. or stress to get 100% cover. Some is better than none.