Fiberglass Insulation???

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Original poster
Jan 30, 2011
I have exhausted my internet research skills and have to ask you fine folks..

What is your take on fiberglass insulation? I found 3 examples of use in "hot" smokers, but really no hard facts or concerns. Lowe's sells a non faced, formaldehyde free, R30 insulation and everything I've read from the manufacturer and fire/heat rating sites is that something like this could handle up to 850 deg. but I still concerned about toxins and breakdown.

My build is a upright freezer and the inside metal panels are a fairly heavy stainless, I don't believe the temps would exceed 350- 400 max. I'm going with a propane burner and don't see how this could really cause a problem. I wanted to run this past you folks for your opinion and/or maybe something I might be missing. Thanks fer yer help, BK
BigK, personnelly I would rather not pick glass out of my food,thus a non-covered thermal insulating material is not a good option(IMHO)

I would say,if you want an insulator for those windy and cold days,invest in a Welder's blanket

And I suppose you are going to wrap only the cooking chamber
 I wouldn't wrap the firebox as it

will be OK with just a windblock.

I'm going on the fact that you have a firebox.If you have a belly burner or other type of smoker,the welder blanket is good.

Opps, read the post again,but even though you may be covr-erring the insulation.I would get an encapsulated version.(IMHO)

Hope this helps and remember,

Last edited:
Not wanting to throw you a curve, but fiberglass insulation, which is rated in R value, is usually for home construction, it will work, but there are better solutions. 

You might want to look into refractory insulation, it's rated in K value, it usually comes in rigid sheets, if you search for BBQ Engineer, he has a very detailed thread on the insulated smoker he built, ...if you decide to use it you should be able to find some at a Plumbing and Heating supply for contractors.

Hey, thank you guys for the info. I really don't want to go fiberglass, but price is I'm gonna wait and look fer something a little better...Thanks again!             BK 
This is my 3405BGW GOSM insulated on three sides.  Behind the sheet metal edging is loose fiberglass insulation.  I have operated this at 400+ degrees with no problems.  The insulation significantly improves temperature in winter and on windy days.  I also have a concrete "heat sink" added to the bottom shelf that makes a huge difference in getting the temperature back up after opening the door.  Empty, I can reach 225 degrees within 6 minutes, 350 degrees in 10 minutes.  With the needle valve, I can get the temperature to just about anywhere I want from 140 to 400+ and keep it fairly close to the desired temperature.  All of the hardware can be had at any hardware store - my next improvement is a gasket on the door.

As to using fiberglass insulation - the melt point is well beyond any smokers operating temperature.  Although there are higher r-value materials, fiberglass is super cheap and just needs 4"-6" of insulating space.

In all, the cost for the entire cart was ~$75 and a couple of weekends building it - well wirht the investment.

I also have a box to put on top of tank with a 200 watt mini-heater that keeps the regulator warm in cold weather (water in the tank freezes and restricts the flow of propane).

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