Curing question

[Patrick.S]

Good afternoon. I’ve finished my dome and chimney and I’ve insulated with mineral wool. I’m planning on a layer of perlcrete before rendering. Should I start curing fires before or after adding the perlcrete?

[david s]

Because a perlcrete or vermicrete mix requires so much water, there is a lot of free water that needs to be removed after the mix has set to prevent issues from expanding steam and it’s reduction of the insulating capacity of the layer. It is therefore advisable to allow it to dry for at least a week before any drying fires which will further dry the perlcrete layer.