Packing Peanuts Attic Insulation

I m not convinced that it s effective or even safe.

Packing peanuts attic insulation.

We found millions of packing peanuts loose in the attic presumably intended to function as insulation. Plastic peanuts hold air that helps cushion whatever is being shipped. The r value of polystyrene is about 4 0 per inch. Osborn a former associate editor replies.

If they get wet they ll dissolve and they re made to be highly biodegradable so they ll break down pretty quickly anyway. But the problem with using packing peanuts for attic insulation is that while the individual peanuts may have an r value of about 4 0 per inch the peanuts have large air spaces between them which allows air currents to easily flow through a layer of packing peanuts. The problem comes from the large interstitual spaces between the pieces. Good insulation works by trapping air.

The older kind might work okay. Most packing peanuts are made of polystyrene. Another problem is that newer environmentally friendly cornstarch peanuts dissolve when wet. The very reason why plastic peanuts work well as packing makes them a bad choice for wall insulation.

Has anyone ever seen this before. In a wall cavity they would offer little resistance to air movement so they would be of limited r value.