Fire blanket versus masonry

Our local refractory told me we could use Castable mortar over the fire brick and then a layer of standard masonry brick (not veneer) without using a blanket. Is this true? Can Castable mortar applied directly to the fire brick work if using standard brick on the outside over the Castable? Will the insulation be the same or potentially better or worse?

Hi Mel, and welcome to the BrickWood forum!

I know you had another question and I’ll address that on the other thread you started.

As for this one—I would not follow that advice. The Mattone Barile (or Barile Grande) is a terrific design for a do-it-yourself’er, and even a novice. BUT…it was carefully designed for maximum performance and safe operation using the materials and design specified in the detailed directions.

I don’t know what’s in it for your local refractory supplier, other than selling you some castable that otherwise is not needed in this oven. What I will say is that if you go that route, you’ll be building a different oven than the BrickWood design. The castable will certainly provide some insulation, but I have no basis even to begin comparing that with the mineral fiber blankets (one of the very best insulation materials for ovens) called for in the BrickWood design.

My advice on this is to stay with the specified specs and materials. They include some simple alternatives for the more expensive materials, especially the heat resistant mortar; but if you wish to get your oven up to sustained pizza-baking temperatures, stick with the design for the arch/insulation/stucco shell.

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Yes it’s directly on the ground behind a small wall. I’ll try to post a photo I took of the area but it night. I’m not home

Q: I am going to purchase your barrel form but wanted to see what else I needed for my build so I could make up a supply list before making an appt. at my local refractory. I’m going thru your supply list I have some questions. I’m seeing silica, cement, fire clay, hydrated lime, and sand. The guy at the refractory said I just need Mortar mix (#413) which is the mortar for the fire brick (it comes in 55 lb bags).

A: If you are going to make your own High-Temp mortar, you need Silica Sand, Fireclay, Portland Cement and Lime (about $150 for the entire oven). If you want to purchase a pre-made / dry high-temp mortar, then Mortar Mix 413 is perfect (about $50 per bag x 7 bags = $350 for the entire oven).

Q: Castable Concrete for going over the chicken wire that goes over the fire blankets?

A: This is INCORRECT. Castable Concrete (Castable Refractory) will NOT cure unless it is exposed to heat. If you place Castable Refractory over the oven, it may feel hard after a few days, but it is far from cured as it needs direct fire contact to cure. You need to use standard mortar for your shell… but preferably DRY STUCCO (scratch, brown or final coat… all will work).

Q: The area where I am putting my oven is already waist high. I will be building from dirt. So no need for a base structure. I will just be pouring a standard concrete pad. I don’t need the concrete pad included in my supply list.

A: If you are building this oven on a hillside or on direct dirt, you absolutely, positively have to make sure your base is WELL insulated… well draining… and not in direct contact w/ the dirt. A cold dirt base will steal your oven of it’s heat and it will never get hot enough to properly bake pizza or bread. We don’t have directions on how to build a hillside slab – but just know, it has to be WELL insulated and able to drain.

IMPORTANT / URGENT - Before you ever touch that shovel, can you PLEASE send us pics of the hillside / waist level ground where you want to build your oven. I’m no expert on drainage… but I do know the cold earth will rob the heat from your oven like a sponge if it is not properly insulated (bottom / sides)! So please share several pics w/ the forum and hopefully we can get some good suggestions your way before you begin construction.