Have recently moved into a dormer bungalow, and gradually finding a long list of things to do. Somewhere near the top of this list is to add more insulation to the floor of the eaves spaces. I have read most of the posts on here - just want to run my thinking past anyone who knows - and ask for a few tips:
First problem is that the existing insulation is thin and compacted. Seems a simple solution - lay more. Fiddly bit is taking up the (nailed down!) boards, avoiding the literally 100's of wires (this place is overwired for AV in every room - not something that is currently adding value in my eyes!) and increasing the depth of the rafters where they are only 4". I can manage that. What I don't want to do is block off the ventilation - I have continuous soffit ventilation around the whole perimeter - but want to get the new insulation as tight as possible into the rafter / joist gap. I have found 'refurbishment rafter tray' on the web - has anyone used these? Are they easy to fit?
Second issue is around the walls of the first floor rooms. Most of these have 4" stud walls with tight fitting dense insulation mat, in places they have skimped and pushed loose rockwool into the cavities, where it sags and falls out. I was thinking of adding 1", or 2" thick kingspan board to the outside of this studwork to increase the insulation some more. Not sure if this would be worth while, the sloping sections of the walls only have 2-1/2" of the rigid board between rafters, and there is more sloping surface area than vertical. Any views?
Next: The plasterboard on the vertical and sloping sections of first floor rooms are backed with polythene - do you think the flat roof will be the same? If so then the vapour from that part of the house will be contained - I don't see why it's not left porous as the flat ceilings in a normal build would be??
Last: Seen some reports on here that the insulation on offer in the sheds is not very good. True? Where does a mere mortal go to buy good insulation - and rafter tray for that matter?
many thanks for replies.
First problem is that the existing insulation is thin and compacted. Seems a simple solution - lay more. Fiddly bit is taking up the (nailed down!) boards, avoiding the literally 100's of wires (this place is overwired for AV in every room - not something that is currently adding value in my eyes!) and increasing the depth of the rafters where they are only 4". I can manage that. What I don't want to do is block off the ventilation - I have continuous soffit ventilation around the whole perimeter - but want to get the new insulation as tight as possible into the rafter / joist gap. I have found 'refurbishment rafter tray' on the web - has anyone used these? Are they easy to fit?
Second issue is around the walls of the first floor rooms. Most of these have 4" stud walls with tight fitting dense insulation mat, in places they have skimped and pushed loose rockwool into the cavities, where it sags and falls out. I was thinking of adding 1", or 2" thick kingspan board to the outside of this studwork to increase the insulation some more. Not sure if this would be worth while, the sloping sections of the walls only have 2-1/2" of the rigid board between rafters, and there is more sloping surface area than vertical. Any views?
Next: The plasterboard on the vertical and sloping sections of first floor rooms are backed with polythene - do you think the flat roof will be the same? If so then the vapour from that part of the house will be contained - I don't see why it's not left porous as the flat ceilings in a normal build would be??
Last: Seen some reports on here that the insulation on offer in the sheds is not very good. True? Where does a mere mortal go to buy good insulation - and rafter tray for that matter?
many thanks for replies.
