What's a good insulating foam to use for a cat shelter like this? Basically, I want to fill all the areas between boxes where I don't have sufficient whatchamacallit insulation so boxes don't move around.
Someone told me some of that insulation melts plastic. Sounds like bs, but confirm. I also don't want the cats breathing any hazardous fumes.
some kinds of insulation eats pvc, you can't run electric wire over some insulation for example, specifically the hard board type stuff
you could use the horrible rolls of wire wool insulation type stuff, perhaps some of those airbags you get for packing parcels or stuff it with packing peanuts.
Shelter for what? Stray cats? You're trying to over engineer this thing.
The vast majority of animals are more than capable of keeping themselves plenty warm on their own in cold air. What gets animals in the end is moisture which inhibits their coat's insulating qualities, or drafts strong enough to leach the warm air trapped by their coat.
A single wall box with a protected entrance to keep drafts at bay and a vent hole near the top to let warm moist air leak out is all animals need.
Straw or shredded paper can also help them nest if it gets any colder.
I would find a way to shield the entrance. That allows easy entrance and egress while dampening air flow. Maybe a piece of fleece with flaps cut, folded over a few times then attached to the inside of the box over the entrance. Some holes along the top will let light in and moisture out.
>muh feral cats
No one cares. These boxes are great for outdoor farm cats too.
Pretty much anything will work from crumpled up newspaper/magazine pages to pieces of cardboard to straw/hay.