Advice on Sealing ACX Fir Plywood for Pizza Oven Stand

Woodshop
1

I’m building a pizza oven that uses a metal stand for the base (originally purchased off Craigslist and modified). I’ll be layering two sheets of ACX 3/4" plywood, thinset + 1/4" cement board (+ maybe redguard membrane seal) for the top that oven sits on, and eventually tile around the perimeter of oven.

Anyways, I’ve laminated the two pieces of ACX fir plywood together, and looking to further water proof/resist for longevity. Theoretically, it shouldn’t be directly exposed to water, but I understand it will always find its way.

For the plywood edges, I’ve come across a couple options in my research:

  1. Kilz Original Exterior Oil-Based Primer

  2. Lathering Titebond III (waterproof) into the edges

For sandwiching plywood to Cement board, would using thinset (as used in normal construction process) be best for adhering the two together; or would something like construction adhesive be best?

Any other thoughts?

Open to other concerns/thoughts as well (though I don’t think there should be concern about plywood base and fire/heat; as the 2.5" of concrete, 4" of insulation, and 2.5" of firebrick will keep the top of stand/plywood cool enough based on research at FornoBravo forums).

OvenPlan
OvenPlan6600×1957 1.33 MB

2

You might consider Oil based Spar Varnish for the waterproofing. It is a pretty traditional waterproofing method used on boats and decks.

Is flammability a consideration? If so anything oil based is probably going to be more flammable (and more expensive) than Titebond III.

3

Consider thin epoxy like MAS brand used on boats. Varnish for UV if it’s exposed to sun.

4

Flex Seal or Plasti Dip?