Packing Peanuts Attic Insulation

Good insulation works by trapping air.

Packing peanuts attic insulation.

Another problem is that newer environmentally friendly cornstarch peanuts dissolve when wet. In a wall cavity they would offer little resistance to air movement so they would be of limited r value. Plastic peanuts hold air that helps cushion whatever is being shipped. I m not convinced that it s effective or even safe.

If they get wet they ll dissolve and they re made to be highly biodegradable so they ll break down pretty quickly anyway. Has anyone ever seen this before. New packing peanuts are made from a type of corn starch. The older kind might work okay.

I m not sure when they switched to the new kind but it wasn t more than five years ago or so. The problem comes from the large interstitual spaces between the pieces. The very reason why plastic peanuts work well as packing makes them a bad choice for wall insulation. 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.

Osborn a former associate editor replies. The r value of polystyrene is about 4 0 per inch.