Hey all...a quick question for the experts….
On the sloping ceilings in my new build dormer, I have planned to put 180mm semi rigid insulation from a particular manufacturer between the rafters which will get me a U value of 0.20, which meets regulations. I had also planned to install a Moy “Vario” Air tight membrane on the underside of the joists and rafters and then finish with a standard 12.5mm slab.
On reflection, I would like to exceed the regulations in as many areas as I can and especially here as it is obviously quite close to the roof/elements…
I know one option is to further batten the rafters etc so as to increase the depth available to me for insulation and thereby improve on the U value. Not against doing this, but I want to consider my options......
Is the following option feasible or does it not make sense or is it contradictory??
Scenario: Fit the 180mm insulation between the rafters, then the Moy “Vario” Air tight membrane stapled to the underside of the rafters, joists etc and then putting on an insulated slab instead of an ordinary one?
Would that work or do the workings of the materials within the different types prevent this as a solution?
I do know that when placing 2 layers of insulation that the one with the greatest effective R value should be placed uppermost to prevent condensation between the 2 layers
I am also asking the supposed “real” experts but wanted the opinion of some of the experienced people here too…
thanks in advance for any help
On the sloping ceilings in my new build dormer, I have planned to put 180mm semi rigid insulation from a particular manufacturer between the rafters which will get me a U value of 0.20, which meets regulations. I had also planned to install a Moy “Vario” Air tight membrane on the underside of the joists and rafters and then finish with a standard 12.5mm slab.
On reflection, I would like to exceed the regulations in as many areas as I can and especially here as it is obviously quite close to the roof/elements…
I know one option is to further batten the rafters etc so as to increase the depth available to me for insulation and thereby improve on the U value. Not against doing this, but I want to consider my options......
Is the following option feasible or does it not make sense or is it contradictory??
Scenario: Fit the 180mm insulation between the rafters, then the Moy “Vario” Air tight membrane stapled to the underside of the rafters, joists etc and then putting on an insulated slab instead of an ordinary one?
Would that work or do the workings of the materials within the different types prevent this as a solution?
I do know that when placing 2 layers of insulation that the one with the greatest effective R value should be placed uppermost to prevent condensation between the 2 layers
I am also asking the supposed “real” experts but wanted the opinion of some of the experienced people here too…
thanks in advance for any help