Hi, I'm looking for some advice on insulating under our inner sills. I've seen cavity closers but not sure if they'd fit in our scenario. I then thought would rock wool on a damp proof sheet suffice? The sides appear to be mortered up. Any advice?
Square up the protruding stone with a small angle grinder, then slot 40mm celotex insulation down into the cavity keeping it a couple inches beneath the top of the stone, then wedge more celotex down on top of a piece of 18" DPC between the brick and stone to close off the cavity, keeping it flush with the brick/stone.
Thanks for taking the time to reply. Am I right in my understanding of your explanation: so celotex in first then DPC would sit on the stone go down in the cavity then back up onto the brick with some more celotex sat in it?
Pretty much yes, tuck the DPC down into the void but fold the edges up over the stone and brick once you've wedged insulation between. Cut off any excess when you come to cover with plasterboard or whatever.