Hi All,

Would appreciate your thoughts on the best course of action for dealing with loft insulation.

Currently in my reno bungalow I've got a cold loft with a wild mixture of insulation between joists. There's about 50mm of vermiculite (thickness likely varies a lot over the attic surface), then there's areas of some old loose-fill fiberglass and old grey fiberglass sheets that appear to be disintegrating - some of the stuff turns into dust if I try to pull a piece of it out.

Then there's patches of newer fiberglass sheets on top.

Overall, I'd say about 150-200mm thick.

I expect that fitting quality is going to vary quite a lot, e.g. there's sections where the previous owners installed rooflights and the workies pushed the insulation aside and left the area around the new light fittings uninsulated.

For some reason, there's savolit-type wood wool boards sandwiched between the felt and the rafters, but I doubt they add much to the insulation value?

I expect to be doing a fair bit of work in the loft: re-plumbing the heating system, removing the remains of a prehistoric solar thermal water heater set-up, replacing light fittings, re-wirting the electrics at some point. I would also like to have a section of the loft eventually boarded up for lightweight storage.

Since there's [ancient & broken] solar thermal panels on the roof already, this makes me wonder whether I should consider putting new PV ones, which would require more loft work.

Highly friable fiberglass insulation is not the most pleasant material to work with, and loose vermiculite is a bugger when I need to drill a new ceiling penetration or even just replace a spotlight, so I've got half a mind to just rip out the old stuff and install something new & modern.

I believe vermiculite insulating properties are mediocre, and I've read that old decomposing glass is not highly effective either.

On the other hand, there's about 120sq m of area to cover, which makes me cringe when thinking about the time it might take to remove the old stuff, and the time & potential cost of fitting new insulation sheets to replace 200mm of stuff that is already keeping the house warm.

So, would a complete overhaul be a waste of time and money, or would I thank myself for this investment later?

I've had a bucket of samples tested for asbestos and all came back negative.

Is there a market for reused loose vermiculite to offset the cost of buying new insulation? Or do people stay away from it because of potential asbestos contamination risks?

As always, thank you very much for the advice.

Edited 1 hour ago1 hr by tetris

Your negative tests are reassuring, but with several different fills I would avoid making more dust until you are sure the samples covered each material; if not, get the suspect areas assessed before disturbing them.

Given the patchy 150 to 200mm and your planned services work, I would coordinate the plumbing, wiring and any PV cabling first, then make the loft consistent. There is no need to bin clean, dry, intact modern quilt: keep it if it can be laid flat, and remove the loose or badly degraded material. After levelling, top up to around 270mm mineral wool equivalent, filling gaps but keeping eaves ventilation clear.

I would not try to sell or reuse loose vermiculite. Even with reassuring tests, dust and contamination concerns make it poor value and there is unlikely to be a dependable market. Bag and dispose of it appropriately rather than spreading it about.

For storage, use raised loft supports so boards do not squash the insulation. Keep junction boxes accessible and leave the clearance around downlights required by their makers; have the electrician check cables before covering them. The wood wool boards may add a little, but are not a substitute for a continuous layer at the loft floor.