Hello
Think best I just jump in and describe the situation and hopefully someone a lot smarter than me can steer me in the right direction.
- moved into house 2 years ago and old lime plaster walls were blown and sash windows rotten, replaced with modern gypsum plaster and UPVC windows (i.e. directly contributing to the house not being able to "breathe")
- as part of renovation, I've added 75mm Celotex rigid insulation between all the top floor ceilings joists
- previous owners did a loft conversion a long time ago which included a direct open staircase up to the loft (i.e. no hatch or firedoor as per modern regs), ultra thin sheets of polystyrene insulation above the loft plasterboard and added a thick (non breathable) underlay on one-side of the roof only (presumbly as the builders only lifted one side of the old roof as only that one side has velux windows added)
Fast forward to today and we have a humidity issue, I don't know if there was one from day 1 as never tested it but know over the past 2 years I've spotted mold in the loft. Plugged in an humdifier and over time its dropped down from 80% to steady around 55%. Additionally I noticed when fitting the top floor ceiling insulation that on the side of the house without an underlay there must be some broken slates as some of the woodwork was showing signs of damp.
So ... at a minimum I need to a roof to repair some broken slates but wondering (if finances allow) what would be the ideal work to take advantage of the scaffolding being up.
1) Add more insulation between the rafters or with the PIR between the ceiling joists below, is this a false economy and potentially make the humidity issue worse?
2) Add a breathable membrane/underlay to both sides of the roof? or just adding to the side with no underlay at all will suffice?
Thanks in advance!
Think best I just jump in and describe the situation and hopefully someone a lot smarter than me can steer me in the right direction.
- moved into house 2 years ago and old lime plaster walls were blown and sash windows rotten, replaced with modern gypsum plaster and UPVC windows (i.e. directly contributing to the house not being able to "breathe")
- as part of renovation, I've added 75mm Celotex rigid insulation between all the top floor ceilings joists
- previous owners did a loft conversion a long time ago which included a direct open staircase up to the loft (i.e. no hatch or firedoor as per modern regs), ultra thin sheets of polystyrene insulation above the loft plasterboard and added a thick (non breathable) underlay on one-side of the roof only (presumbly as the builders only lifted one side of the old roof as only that one side has velux windows added)
Fast forward to today and we have a humidity issue, I don't know if there was one from day 1 as never tested it but know over the past 2 years I've spotted mold in the loft. Plugged in an humdifier and over time its dropped down from 80% to steady around 55%. Additionally I noticed when fitting the top floor ceiling insulation that on the side of the house without an underlay there must be some broken slates as some of the woodwork was showing signs of damp.
So ... at a minimum I need to a roof to repair some broken slates but wondering (if finances allow) what would be the ideal work to take advantage of the scaffolding being up.
1) Add more insulation between the rafters or with the PIR between the ceiling joists below, is this a false economy and potentially make the humidity issue worse?
2) Add a breathable membrane/underlay to both sides of the roof? or just adding to the side with no underlay at all will suffice?
Thanks in advance!
