Packing peanuts for insulation in a solar kiln

[brdmkr]

DanG geeeenious idea.  Dan.

[Den Socling]

I said to compact them to reduce the space around them. If you took a cavity in a wall and filled it full of those foam peanuts and then you compacted the pile from above to close the space between the peanuts, they would be insulation.

[Rockn H]

Polyurethane foam insulation has an R value of between 6 and 8 per inch depending on density according to most manufacturers.  So if you have 6 inches of "solid" foam you'd have an R value of 36.   Dead air space is only bad because of convection, right?  If you fill the wall from the top ,and compress the heck out of it ,won't the peanuts be packed tight enough to assume at least 5 solid inches?  That would be an R value of 30.  Even if you knock off another inch, you're looking at an R value of 24.  That would be as good as your standard fiberglass insulation.  Heck if you can get enough go with a 10" wall cavity.  That's about how thick they used for ice houses and all they had was sawdust for insulation.  If it's free try it.
If any of my figures are too far off somebody correct me.

[WkndCutter]

Those packing peanuts will afford some insulation value but there will be some settling over time.  Putting them into plastic bags will help with that.  Depending on your wall size you will need around 2 cuft per wall stud space.  The cost to insulate the whole kiln is going to be considerable using regular fiberglass or sheet insulation.  I would put the packing material into plastic bags and seal the walls on both sides with plastic sheets before putting the wall board on.  Bottom line, free insulation - you can't throw that away.

Andy

[Brad_S.]

I've looked into the foam insulation and consulted a number of 'experts' and all give me different answers. But they all kind of agree that R values are misleading. I was pricing walls 5 1/2" thick and was told "why bother" 1 or 2 inches of foam is better than 5 1/2' of fiberglass, not because of R value but because there is much less air infiltration with the foam. I think-and I have no expertise, this is just a supposition- infiltration around the studs would be the weak link of the packing peanuts.

[isassi]

This got to be really in depth..so here is another look. EPS is great insulation, no doubt. Fiberglass is better still (barring air movement). When we rehab older houses, we now vapor block the external walls, bat the inside, and sometimes moisture block the interior as well. New premium vinyl siding has insulation molded to the siding and flat to the house. This system only promises an "R" gain of 6 or so. R value is a very misleading term for a blanket approach. The bottom line is most homes and buildings are not air tight, leading to heat/cooling loss. All things sealed, then the building materials conductivity is rated. 3 inch fiberglass has a much higher r value then stated, but due to 2X4's and framing, ect. it can not block tranfer, so the rating is only arbitrary. That is why an inch of EPS board on a well insulated house gives such a boost, especially combined with a house wrap and caulking + taping the seams of the EPS with foil tape. Now for the numbers: Insulation is the cheapest by far of all materials to build with, and if the wall cavities allow it or you have access to spray equipment, blown cellulose is a great insulator and is nearly all from recycling. )less the 20 cents p/s/f. 

[brdmkr]

Well, I suppose I will be the proud ownert of 60 cu ft of peanuts!  Man, I hope they work.  If they don't I'll have a mess

[DanG]

Blown cellulose is great insulation, but not recommended for kilns.  The high humidity from the drying wood will soak it with condensation, and it will cease to insulate.  At least, that's what the "Doc" says.

[isassi]

I hadn't even thought of that dang.....very valid point, so I suppose we shoudl say that EPS board would be the best. Thinking further, all those peanuts would trap water in the bottom of the cavities also.