We are about to start a big refurbishment project on a farmhouse that hasn’t been occupied in 20+ years and has become completely dilapidated and uninhabitable. It’s a big job and needs a lot of work, so we will likely have lots of questions, but we’re starting with the roof and I wonder if someone could help us work out the best way to insulate it please, as we’re getting contradictory advice?
It’s currently only tiled, no insulation or membrane at all. We will be taking the tiles off and reusing as many as we can (grade 2 listed, so that is a stipulation of the permission), so we will be able to insulate from above and below. The property is not currently plumbed and hasn’t been heated in the 20+ years since it was last occupied and it was previously heated only with fires. We plan to install plumbing as part of the refurb and the attic will be heated using radiators from a gas boiler. The attic rooms will be used as bedrooms.
We planned to use all breathable materials, as we understand that will be best for the building. Our plan was to use Actis Boost’r Hybrid (an insulated multifoil breathable membrane) with rockwool underneath, then breathable plasterboard and finally lime plaster, but Actis have said we should use a polythene layer between the rockwool and the plasterboard or otherwise their system flags it as a damp risk, exactly what we are trying to avoid. So now we’re not sure what we should be doing. If we have to put a polythene layer in, then surely we may as well use gypsum plaster below that? If we keep a ventilation gap between the rockwool and polythene, would this prevent damp? Or should we omit the polythene layer, even if their system flags it as a damp risk? Or should we be doing something entirely different?
Thanks for your help
It’s currently only tiled, no insulation or membrane at all. We will be taking the tiles off and reusing as many as we can (grade 2 listed, so that is a stipulation of the permission), so we will be able to insulate from above and below. The property is not currently plumbed and hasn’t been heated in the 20+ years since it was last occupied and it was previously heated only with fires. We plan to install plumbing as part of the refurb and the attic will be heated using radiators from a gas boiler. The attic rooms will be used as bedrooms.
We planned to use all breathable materials, as we understand that will be best for the building. Our plan was to use Actis Boost’r Hybrid (an insulated multifoil breathable membrane) with rockwool underneath, then breathable plasterboard and finally lime plaster, but Actis have said we should use a polythene layer between the rockwool and the plasterboard or otherwise their system flags it as a damp risk, exactly what we are trying to avoid. So now we’re not sure what we should be doing. If we have to put a polythene layer in, then surely we may as well use gypsum plaster below that? If we keep a ventilation gap between the rockwool and polythene, would this prevent damp? Or should we omit the polythene layer, even if their system flags it as a damp risk? Or should we be doing something entirely different?
Thanks for your help