I'd like to partly board the loft for storage but also beef up the insulation.
Currently there's fibreglass between the 2"x3" joists - so < 75mm insulation.
The celings below are 1930's lath-and-plaster meaning the effective depth between joists is probably reduced to 60-65mm, and I don't want to do anything to jeopardize them because I think it's only the vinyl wallpaper the previous owner installed that's holding them together.
I don't want to spend a fortune and end up waiting decades for pack back, and I don't want to start a major engineering project either.
Current plan is to board over the central area and lay either 170mm or
2x100mm at right angles to the joists over the unboarded area.I've thought about putting Celotex/Kingspan under the boarding but I'm not sure the extra cost is justified.
I realise insulation/storage/cost will always be a compromise but does the above seem like a reasonable plan?
And do the lighting cables have to be extended to be above the fibreglass to supply a modern low-energy CFL?
Thanks for any advice.