Old duvets as loft insulation

The only problem that may occur is mold, fibreglass and spray foam is mold resistant.

Considering you probably have electrical wires in your loft and the present insulation is fire resistant would it be sensible to add flammable materials?

Old duvets covered in years of accumulated dead skin cells and such stuff are probably more attractive to vermin than standard loft insulation materials?

What old duvets can be used for is to add insulation to windows. ,but I do not think it would be advisable to use them in your loft, but check with your house insurance first

Thanks for your comments. Our duvets are washed quite regularly and are used in duvet covers so I'm not persuaded that they could be attractive to vermin. Also, are they any more flammable than all the other stuff that many of us keep in the loft all the time? There is quite a good air movement in our loft and we have never suffered from mould on anything else kept up there. I suppose my question should have been will they provide a meaningful increase in  insulation.

I wonder if the density of the duvets would be a lot less than proper insulation and therefore unlikely to give much of a thermal lift? The recommended thickness of insulation is between 250 and 270 mm. I think I would just buy more insulation and send the duvets and sleeping bags to a homeless charity?

David

Having just had field mice in our loft I think they'd love some nice soft bedding, they didn't find our proper insulation very tempting but gave it a go! 🐭🐭🐭

Speaking from experience NO!

Mice will bed down, pee in them and even chew them up a bit.

Well you could allow the local cub scouts to get a little supervised camping experience in --  that could keep the meeces on the move if nothing else