I've got two large bags full of small offcuts of woodfibre and two full of the dust from the festool when woodfibre batts (Steico therm) were cut for some IWI we did.

Is there anything useful that can be done with them - by which I'm thinking put them into some kind of breathable bag and use as insulation somewhere - or is it the case that in their raw dust form, not compacted, they're not likely to be very useful as insulators?

I imagine I'll be able to use some of the bigger offcuts in some places, just pains me a bit to throw so many of the smaller peices away as they are pretty pricey!

Sheepswool definitely generates a lot less waste from cutting to fit! Couldn't believe how much woodfibre dust the festool generated (and got clogged up with!)

Thanks for your thoughts

Mix with water (and a bit of lime 'to taste') and use to fill gaps between WF boards (like caulking a boat).

FT, yes it would if in a significant quantity, the absence of which I was seeking to imply by hi-jacking the culinary 'to taste'. I sometimes (but, for example yesterday, not always - I don't bother when I have not got any lime 'on the go') add a tiny 'splot' of lime to a bucket-full to make the mix a little more 'sticky' (and the gaps in question are very small anyway). Yesterday's were due to a v slight set-back of a rafter out of line with the main posts, so the 'bed joint' opened about 3mm at its widest.

Depends how ordinary your 'ordinary builder' is. Some people think I enjoy the tedious stuff like this. I HATE it, but I feel it has to be done. Some disagree.

To put the lime/WF mix in context I am probably talking about a spoonful in a bucket-full of WF (if indeed I bother) - maybe 50 or 100-1?

Some use squirty-foam in WF joints. I just feel that if I have (or anyone has) gone to the trouble and expense of using WF it seems a bit 'wrong' to use plastic foam to fill the gaps. Just a personal gut- feeling.