Helping a friend add insulation to their loft. It's a 1995-built detached house in the South of England. It has ~ 100mm of the old style yellow insulation. Most of this is in good condition without signs of damp or dirt. I'm adding 200mm Knauf roll over it and boarding the middle section. A new metal well-sealing loft hatch from Jupiter Blue, a new loft ladder, a central area of raised boarding (3x CLS risers on the trusses) and LED 5' strip lights are making it into acceptable storage space.
One side area of the yellow fibreglass has a surface layer of dirt. When they moved in, the end soffits were falling to bits, which they quickly got replaced with new timberwork on that side and uPVC all round. The dirt is dry and flaky/crusty to the touch. I expect it probably got blown in while the soffits were in poor condition. Of course that was the end that got prevailing winds. The existing roof felt looks OKish, no obvious rips.
There is no obvious concentration of dirt like you might expect if there were upward moisture / condensation issues. The eave vents are accessible. I've replaced the bathroom downlighters with LED IP65 sealed ones, and capped them with ThermaHoods for fire safety / good measure.
My question is: for that dirty area, is it better to strip out the yellow stuff and replace with a base layer of 100mm Knauf?
For the small extra cost this would seem to give peace-of-mind. However the dryness and evenness of the muck makes me think it might be a non-problem?
Will try to get photos tomorrow.
One side area of the yellow fibreglass has a surface layer of dirt. When they moved in, the end soffits were falling to bits, which they quickly got replaced with new timberwork on that side and uPVC all round. The dirt is dry and flaky/crusty to the touch. I expect it probably got blown in while the soffits were in poor condition. Of course that was the end that got prevailing winds. The existing roof felt looks OKish, no obvious rips.
There is no obvious concentration of dirt like you might expect if there were upward moisture / condensation issues. The eave vents are accessible. I've replaced the bathroom downlighters with LED IP65 sealed ones, and capped them with ThermaHoods for fire safety / good measure.
My question is: for that dirty area, is it better to strip out the yellow stuff and replace with a base layer of 100mm Knauf?
For the small extra cost this would seem to give peace-of-mind. However the dryness and evenness of the muck makes me think it might be a non-problem?
Will try to get photos tomorrow.
