I've got an uninsulated 94 year old house, with a paltry heat pump. I already plastic-wrapped the windows, added sweepers to the doors, etc. The attic is not insulated, so that's my next target.

I've got a line on a source of "free" expanded polystyrene blocks-around 2'x2'x2". They're packaging waste, but are clean enough for my purposes. Same material as your coffee cup/disposable cooler.

Are these that different from the pink panther XPS sheets safety wise?
If I insulated my house with the EPS panels do I run a higher fire risk?

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment