I am putting 90mm phenolic between rafters with 60mm layered over that then 12.5 vcl plasterboard. I have a 1360mm wall on one side and am making a smaller wall approx 400mm inside one of the triangular voids for storage with access to plumbing manifolds.
All joists in in space still has the normal attic insulation rock wool or whatever it is these days.
In the cold void, there is another layer on top.
My question is where the walls meet the floor. Is it standard practice to just run the PIR board level to the floor and leave the normal insulation underneath
or
Cut the rock wool and run the PIR into the joists and finish flush against the plasterboard below.
Its extra cost but isn't it a much easier route for vapour to get to the cold space if its just rock wool and cold the other way?
All joists in in space still has the normal attic insulation rock wool or whatever it is these days.
In the cold void, there is another layer on top.
My question is where the walls meet the floor. Is it standard practice to just run the PIR board level to the floor and leave the normal insulation underneath
or
Cut the rock wool and run the PIR into the joists and finish flush against the plasterboard below.
Its extra cost but isn't it a much easier route for vapour to get to the cold space if its just rock wool and cold the other way?
