Safe Materials to Build a Wood Smoker/Smokehouse

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My take on the BBQ/smoking debate with respect to construction....

My smokehouse is lined top to bottom with hardi board. It has the same heat refraction index as steel, and will hold a very even temperature. When smoking sausages, I can keep the temps. +or-3*F. Very steady as she goes.

Becasue of the hardi board, I have no issues cooking brisket, pork butts -even chickens and turkeys- in my smokehouse. But- I never let the heat get above 275*F.

If you wanna do both, this is what I recommend....complete 100% coverage on the inside with hardi board. If you wanna go hotter, I'd go a different route.
Thanks for the reply, indaswamp indaswamp . If I were to go with a hybrid system, this is essentially what I was thinking. The main issue I have with lining the inside with hardi board is the reason for the title of this thread. All of the cement board / tile backer / hardi board I have looked at contains silica. I have been unable to find any definitive evidence regarding the safety of the different types of cement board. For that matter, I also wonder about using plywood. The binders in that can be an issue. Obviously, I would never get the smoker to the point of needing to worry about the melting point of the various substances. I am just concerned about the potential for off-gassing of any product. Perhaps that can be taken care of by doing a couple burn-off sessions.

I have looked at different threads, both here and in other forums, regarding the safety of various products, and most of the posts are around a decade old. If anyone has any up-to-date information showing that these substances are safe for smoking at hot smoking temperatures, please let me know.
 
Thanks for the reply, indaswamp indaswamp . If I were to go with a hybrid system, this is essentially what I was thinking. The main issue I have with lining the inside with hardi board is the reason for the title of this thread. All of the cement board / tile backer / hardi board I have looked at contains silica. I have been unable to find any definitive evidence regarding the safety of the different types of cement board. For that matter, I also wonder about using plywood. The binders in that can be an issue. Obviously, I would never get the smoker to the point of needing to worry about the melting point of the various substances. I am just concerned about the potential for off-gassing of any product. Perhaps that can be taken care of by doing a couple burn-off sessions.

I have looked at different threads, both here and in other forums, regarding the safety of various products, and most of the posts are around a decade old. If anyone has any up-to-date information showing that these substances are safe for smoking at hot smoking temperatures, please let me know.
silica = sand.....
the materials to manufacture hardi board are inert. I looked at this when I built mine. I went an extra step and also lined the inside with aluminum flashing for a good seal. Not necessary as once the patina builds up, it will seal the pores in the hardi board.
 
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I came into my build with the same goals and concerns as you. I have three kids ages 4 and under, so I didn't put anything into mine that I wasn't sure was safe. Every bit of research I did lead me to believe that the hardiboard is safe. The only real dangers is during cutting, when you have a risk of breathing in the particles.

As for plywood, I found some at Home Depot with a soy based glue. It doesn't have any of the nasty stuff that regular plywood has.

But mine was also a multi-use build. Its roughly 2'x2'x6.5' and runs off charcoal. It worked great for bbq-ing in August and September, but got very hard to control when the weather started to get cold. I haven't bothered to run it in a few months. Its just too hard to keep the temperature up. In the next couple weeks, I'm going to throw a propane burner and pellet tube in there to try to make it usable.

So to answer your question, there are safe materials to build it out of. But don't bother to make it both a smoker and bbq-er. Its just not worth it. Once I get enough use out of this to justify it, I'll be designating it for just a smoker and find myself a nice offset for cooking.
 
Interesting discussion and helpful information. Just as SD Smoker, I am pondering/planning a smoker (vs the off-set I built) as well. I had the same concerns about materials and after reading through all the threads I could find, I am planning on this:

  • Small smoke house (on wheels),
  • Only want to run up to about 190F at most since I have an off-set
  • approx 14"x20"x36"
  • Charcoal for heat (I have about 500lbs I have been collecting at clearance sales the last couple years),
  • Exterior will be cedar fence boards with a structure of 1 inch pine to attach to,
  • Will use the Hardi board for lining the "firebox" where the charcoal will set and put a sheet steel lining over that,
  • Cook chamber will be lined with 26 gauge sheet steel. There is a local company that has remnants that are about 1/2 the cost of new steel. 26 gauge will be lighter and easier to cut/bend for me. The door will also be cedar exterior and sheet steel facing inward.
  • I also have a fair amount of hickory pieces leftover from my kitchen remodel so I am using the hickory as trim or where I need wood inside the cook chamber, such as shelf brackets or dowels to hang things. Yes, I put hickory in my kitchen... refaced the cabinets with 1/4 inch hickory facing. The grain is amazing....
  • I plan on using stainless steel fasteners to hold it all together as well. Even if the temps do not get up too high, I still shy away from zinc coated, galvanized etc....
I know it is kinda over engineered, but that is me and I need another overly complex project to work on.

SD Smoker are there any shops specializing in metal fabrication/metal supply in your area? If you go that route, it may be cheaper than buying at a big box store.

Nate 52, great info since you have what I am working on. Link to pics??

Once I get started, I will post a build thread but I have been researching and following this discussion. Good Luck and enjoy the build. That is half the fun!!
 
I came into my build with the same goals and concerns as you. I have three kids ages 4 and under, so I didn't put anything into mine that I wasn't sure was safe. Every bit of research I did lead me to believe that the hardiboard is safe. The only real dangers is during cutting, when you have a risk of breathing in the particles.

As for plywood, I found some at Home Depot with a soy based glue. It doesn't have any of the nasty stuff that regular plywood has.

But mine was also a multi-use build. Its roughly 2'x2'x6.5' and runs off charcoal. It worked great for bbq-ing in August and September, but got very hard to control when the weather started to get cold. I haven't bothered to run it in a few months. Its just too hard to keep the temperature up. In the next couple weeks, I'm going to throw a propane burner and pellet tube in there to try to make it usable.

So to answer your question, there are safe materials to build it out of. But don't bother to make it both a smoker and bbq-er. Its just not worth it. Once I get enough use out of this to justify it, I'll be designating it for just a smoker and find myself a nice offset for cooking.
Hi N Nate52 , after doing more research myself, I agree that the hardiboard is safe once you are done cutting it. As far as the plywood, I looked at the product you are describing. Unfortunately, there is no Home Depot anywhere close to me (one of the disadvantages of living in South Dakota), and they don't deliver this particular product.

After doing even more research, I have come to the conclusion that I am going to use wood boards, insulation, and drywall for my construction. I have fiberglass insulation from a roofing project that will otherwise likely go to waste, and I will sandwich that in between the wood and the drywall, so I don't have to worry about any fiberglass getting into the smoking chamber. Why drywall vs. hardiboard? Roughly the same price, MUCH lighter (1/2 the weight) per square foot, better thermal mass, and lower U-value/higher R-value. Why wood vs. drywall? Same reasons - for 1" thickness for both products, wood is cheaper (by about 1/3), lighter (by about 1/3), ever so slightly better thermal mass (planning to use pine, so it has a better thermal mass than a hardwood), and lower U-value/higher R value.

There was one other major factor that went into my thought process. To me, it's an indication of a product's safety when certain items such as plywood and hardiboard have Safety Data Sheets listed on their websites, and products such as pine boards and drywall have none. It's an assumption on my part, but I would think that the latter two products would need them if safety were a major concern.

If I want to take safety to another level to virtually eliminate any chance of the smokehouse catching on fire, I can line it in aluminum or steel.

Is this going to be heavy? Without a doubt, this will be a beast of a unit, likely coming in at around 300-350 pounds if I stick to my original specs. It would be even worse if I use plywood and hardiboard. I was originally thinking of making this a portable unit, but I am more interested in temperature stability, leading to a better finished food product, than portability. If push comes to shove, I can always move it with a 2-wheel cart.
 
Interesting discussion and helpful information. Just as SD Smoker, I am pondering/planning a smoker (vs the off-set I built) as well. I had the same concerns about materials and after reading through all the threads I could find, I am planning on this:

  • Small smoke house (on wheels),
  • Only want to run up to about 190F at most since I have an off-set
  • approx 14"x20"x36"
  • Charcoal for heat (I have about 500lbs I have been collecting at clearance sales the last couple years),
  • Exterior will be cedar fence boards with a structure of 1 inch pine to attach to,
  • Will use the Hardi board for lining the "firebox" where the charcoal will set and put a sheet steel lining over that,
  • Cook chamber will be lined with 26 gauge sheet steel. There is a local company that has remnants that are about 1/2 the cost of new steel. 26 gauge will be lighter and easier to cut/bend for me. The door will also be cedar exterior and sheet steel facing inward.
  • I also have a fair amount of hickory pieces leftover from my kitchen remodel so I am using the hickory as trim or where I need wood inside the cook chamber, such as shelf brackets or dowels to hang things. Yes, I put hickory in my kitchen... refaced the cabinets with 1/4 inch hickory facing. The grain is amazing....
  • I plan on using stainless steel fasteners to hold it all together as well. Even if the temps do not get up too high, I still shy away from zinc coated, galvanized etc....
I know it is kinda over engineered, but that is me and I need another overly complex project to work on.

SD Smoker are there any shops specializing in metal fabrication/metal supply in your area? If you go that route, it may be cheaper than buying at a big box store.

Nate 52, great info since you have what I am working on. Link to pics??

Once I get started, I will post a build thread but I have been researching and following this discussion. Good Luck and enjoy the build. That is half the fun!!
Hi HowlingDog HowlingDog , apparently you and I both like the over-engineered concept. Having said that, I would rather put more thought, time, and money upfront into a project and build a quality product than to cobble something together in a half-a**ed fashion and then spend even more thought, time, and money trying to undo or fix my mistakes/shortcomings.

Glad to hear you have so much material already around. It will definitely make your build cheaper in the long run.

We actually have a metal fabrication shop in the town I live in. I have talked to the owner a little bit about using a steel sheet for the inside of the smokehouse. They can bend the steel in two places and basically replicate the dimensions of my smokehouse, although there would still be seams one way or the other, since their biggest sheets are 4' x 8', and my smoker plan right now is 3' x 3' x 5'. It may just be easier to buy a couple rolls of aluminum and cut that myself. I also talked to one of the guys that works there about welding the steel in the smokehouse. He said that anything lighter than 14 gauge is really difficult to weld properly. Basically, it's very easy to blow right through it. I think the 26 gauge is great for lining your smokehouse without adding much more cost or weight, and using the stainless steel screws would be the best way to affix the steel. You are correct on the galvanized - stay away from it. It's not worth the risk.

As far as the hardiboard, please see my response to N Nate52 . It sums up my research and opinion on what to use on the inside. I am certainly not an authority on construction materials, so please feel free to poke holes in my thought processes if it's unsafe or if there is a better build.

You are right, HowlingDog, the build is half the fun. Good luck with your project. I will be interested to see your pictures.
 
Okay, so I may have already shot a hole in my theory about using drywall. I looked a little closer at the USG website, and it says you should "avoid exposure to sustained temperatures exceeding 125°F (52°C)." Maybe putting it in the cavity between the boards on either side of the 2x4's and alongside the insulation would keep it from reaching that temperature while still providing some of the other properties mentioned earlier. Of course, it might just be overkill, too.
 
Just because a material has an MSDS sheet does not imply that it is unsafe. OSHA mandates MSDS for damn near everything made for consumers.....even the tags on pillows......
 
At what temperature?
It does not have to be a very high heat. Rapid heating like in a smoker, and subsequent cooling off after smoking is finished would do it. It's the constant rapid heating and cooling that'll so it. Drywall is brittle and has not internal fiber structure to help hold it together as it expands. Hardi board has cellulose fiber for internal structure and can withstand heating and cooling as it expands. Hardi board is also rated for heat and can be used as backing for a brick fireplace in a home.
 
...drywall will crack from the heat and humidity in a garage.....
Are you talking about smoking or BBQ? According to USG's website, their drywall is rated up to 125 degrees Fahrenheit, which is well within the range of hot smoking. The humidity is certainly a concern. My goal is to build something well insulated enough that it doesn't have wild temperature swings, regardless of what time of the year it is.

Have you heard of anyone who has tried using drywall in a smokehouse? I'd be curious to see what insights they would have.
 
A fair amount of bad advice here when it comes to materials.If you're not in the trades I wouldn't be giving S SD Smoker advice on how to build something when it comes to a structure where fire is the key ingredient in producing heat.Just saying.
 
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