Questions about Firebrick and Mortar

Discussion in 'Brick Smokers' started by jon mc, Mar 23, 2017.

  1. Hi all, 

    I'm working on my design and procuring materials for an all-masonry offset smoker, and I'm wondering about a couple of things, hoping someone can give me some advice. My plans are currently to use 4" thick CMU blocks for the internal structural walls with a brick veneer on the outside, and on the inside use firebrick on all of the heated surfaces. 

    1) Firebrick - my local brick supplier has 2 thicknesses - 1-3/8 inch and 2-1/4 inch. I'm thinking about using the thinner firebrick for the smoke box and the thicker firebrick for the fire box, just to correspond with the temperatures that I would expect to see when the unit is in operation. Does that sound like the right sort of logic, or do I need to re-think this?

    2) Mortar - should I be using refractory mortar for the firebricks, or a portland cement / sand / fireclay 1:1:1 mortar? What about for the structural CMU block - just use regular masonry mortar?

    Thanks for your help, I'll start posting some photos soon. 

  2. jstrunk2004

    jstrunk2004 Newbie

    I am just about done with a brick vertical. I used 4" solid CMUs with type S mortar and brick veneer. For inside of the firebox on the sides, I used 2-1/4" firebrick laid as stretchers so that they are about 4" wide (overkill but I'm an engineer and that's what I tend to do!). I used a fireclay premixed mortar. It's expensive compared to type S so best to keep joints small, unlike what my mason did. Above the firebox, I used 2-1/4" firebrick laid as shiners with fireclay mortar.
    When I get done I'll post pictures of everything. Hopefully the picture will work!



    Sent from my iPhone using Tapatalk
  3. Thanks very much, this is helpful. I am also an engineer, so I tend to be pretty detail-oriented. I did a dry-set layout this past weekend, and I am ready to start laying block and brick this weekend, so your reply is timely. Good luck!

  4. steveaggie

    steveaggie Newbie

    I used 2 1/4" for everything because it worked better from a design standpoint.  On the smoke box, I think you would be fine going skinnier, especially since you're using block behind it.  I also used refractory mortar.  I can't speak much to the fireclay mix, but the refractory stuff is rated up to 2000 degrees.  With the refractory mortar you don't want your joints over 1/8" because it will crack.  The stuff is a lot like caulk.

    See my thread somewhere on here for my build.
  5. Steve, I looked very closely at your design - it looks great! I patterned several of my design features from your work - I will, once complete, have a large smoker, wood-fire grill, and domed pizza oven all in the same build. I'll post my design and progress photos in a separate thread.

    Thanks a bunch for the input. I have decided to go with the thicker firebrick for the firebox, and the thinner firebrick for the wood-fired grill and smoke box. I am also going to be developing a fire clay-mixed concrete for forming the top of the firebox, which will also be the bottom of the wood-fired grill (much like your design). That is good advice on the refractory mortar; I have found that it is a bit difficult to come by, and I had to order it over the internet. 


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