Steel Stand Hearth Options - 2" thick

[loganc10]

I will be building a 32" homebrew cast oven. To keep it a bit more mobile/lightweight, I opted to do a wood/metal base instead of masonry. I came across a metal pre-made base on Craigslist for a decent price, and pulled the trigger on it. Upon further inspection, I have a couple questions on the best way to do the hearth/top of the base, given the specs I'm forced to work with.

First, I do want to point out that that this will likely only be a ~5 year oven; I'm not looking to over-engineer and I understand there will most likely be some shortcomings with longevity, etc.

Anyways, the stand is made from 2" steel square tube, outer ring of 2"x5" tube, and MDF/sheet metal top and shelf. I ditched the sheet metal and MDF top, and ripped out a few pieces of angle out, to more properly brace the new hearth/top (as well as lower it down to a existing cross brace 2" from top of outer ring). Metal screws and brackets were used to add additional bracing.

Now, to the point of the thread, I'm looking for advice on the hearth/top. As mentioned (and shown in the below picture), I have 2" from the cross bracing up to the top of the outer ring. I thought of two options:

• Layering 2 sheets of 3/4" pressure treated plywood and 1 sheet of Hardiebacker cement board.
  • The overall weight of the oven and insulation/floor will be around 800-900 lbs, so I'm not dealing with the crazy weight that's seen with brick style ovens.
  • Benefits:
    • Light weight, only ~100 lbs
  • Drawbacks:
    • Durability to the elements, structurally sufficient?
    • Sheets come in max width of 48", so two will need to be butted/spliced together to get 56"x56" on each layer.
• Try to do a 2" concrete pour.
  • Benefits:
    • More durable
  • Drawbacks:
    • Very heavy, almost 500 lbs. Trying to keep the whole build under 1000-1200 pounds.
    • Thin concrete pour of <2" when considering a cement board on bottom
    • Expansion/contraction of the concrete and metal ring might cause issues?

I'm open to other suggestions or other comments/concerns with the above approaches.






Thanks,
Logan

[Lou Smith]

Love your idea was wanting to do kind of the same thing with cement piers and a metal top with a 3 inch pour of concrete before insulation foundation. Will be following you this.