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Fiberglass Insulation???


Joined 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


Legendary Pitmaster
OTBS Member
Joined Jul 16, 2008
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:


Smoking Fanatic
OTBS Member
Joined Feb 7, 2009
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.



Thread starter
Joined Jan 30, 2011
Hey, thank you guys for the info. I really don't want to go fiberglass, but price is right...so I'm gonna wait and look fer something a little better...Thanks again!             BK 


Smoke Blower
SMF Premier Member
Joined Mar 27, 2011
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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