Questions About DIY "Mortar"

[BrickandMortarPizza]

Hi all,

New guy here - looking into a pizza oven build in the spring/summer. I live in Canada, and it appears it incredible difficult to come by refractory mortar in large enough quantity to attempt a Pizza Oven at a reasonable price. Currently only available to purchase 3lbs refractory mortar at approx. $30/unit.

I've looked into the DIY 4 ingredient mix that appears to be popular - I haven't been able to locate any "Fire Clay" yet.

Wondering If it would possible to use the same or similar mixture that is used when making a vermiculite form oven. If I were to mix either cement or mortar mix with vermiculite in a ratio of 6:1 or 7:1 Vermiculite to additional mix (Cement or mortar mix), do you think it would hold up?

Another thing I'm trying to factor in is that I live in Canada and its get cold in the winter. -30 Celsius days occur a handful of times a year, where I am, the summer can be very hot also 30+ Celsius

Hoping for some Thoughts/ Advice!

[UtahBeehiver]

No, we see these vcrete or pcrete oven show up on YouTube all the time and it is not in your best interest to use mix as your main dome. It is an insulative mixture. There have been several Canadian builds done in 2020 so look at their builds for clay sources. Although difficult they did find the material. Also check with pottery studios and supply houses for dry clay as well a bricklayer suppliers.

[BrickandMortarPizza]

Thanks for the response - This helps! having a real hard time sourcing fireclay so far. Considering making a drive to the states to go to a big box hardware store a purchase some refractory mortar. The product I found online is this https://www.lowes.com/pd/Sakrete-50-...Mix/1000250707

This seems to be the type of product needed, correct? Also, right now my rough sketch of a plan is build a tunnel style oven with 45L X 45W x 25-30H. What quantity of the 50lbs unit do you think would be needed for this sized project?

Thanks for the help!

[deejayoh]

OR... don't buy fire clay. Many builders (including me, after the first bag of fire clay) use the cuttings from the firebrick as fireclay. Seems to work fine, and trust me, you will have buckets of the stuff that you either need to use or throw away. cut your floor, dry out all the stuff that is in your brick saw, tray, and run it through a mesh screen.

[BrickandMortarPizza]

Deejayoh,

Thanks for the response! only joined this forum recently and the fast responses have been awesome. I actually don't plan on cutting any fire brick. This leads me into my next question actually... I plan on making a tunnel design. The floor being 45Lx45W. Using the 9"L x 4.5"W x 1.5"H bricks this works perfect without having to make any cuts. My question is about how well a 1.5" thick fire brick would hold heat for the oven floor. Thinking about ways to put insulate underneath, but im still not sure. Where I am in Canada, the 9x4.5x1.5 fire bricks are the only ones around. I'd likely have to go to the states or order thicker bricks ($$$).

What are your thoughts?

[david s]

1.5” thick oven walls and floor are generally not considered thick enough to provide sufficient thermal mass required for adequate cooking. Generally 2” is more ideal. In addition 1.5” is insufficient thickness for the mortar joints to provide enough strength. Because of thermal expansion these joints are under greater than normal stress. A barrel vault is not a stable arch in that the forces are uneven (unlike catenary arches), unless bracing or buttressing is used there may be failure long term. Bracing or buttressing can be quite difficult and make the barrel vault actually more complicated to build than a full dome. You may be able to add additional thermal mass both under the floor and over the vault using a castable mix which would also add additional strength.

[deejayoh]

Further to David's input on barrel vault design - make sure you're looking at a design with an inner + outer arch and where the flue is between the two arches. Lots of builders come here having built a design that has the flue coming out of the cooking chamber, complaining the oven won't get or stay hot. That phenomenon will be exacerbated if you use thinner bricks.

That said, what part of Canada? I'm surprised you can only find splits. Those are typically harder to find, or sometimes what you can get at a big box store. Have you tried refractory suppliers? In Canada, surely somebody is selling bricks for fireplace construction!

[BrickandMortarPizza]

Thanks for the replies everyone!

Something I should have made clear from the start (New Guy) - I am planning on making the oven itself out of redclay brick, (standard size), with only the floor using fire brick 1.5" Thick. Finishing the tunnel with a thermal wrap, and a smaller arch opening with flue inbetween main chamber and opening arch. I'm currently in the greater ottawa area - No big box stores have the full sized fire brick - Not Lowes, Not HomeDepot, Not Canadian Tire. The only place I've found them is either in other cities sold by independent suppliers and would need to ship them ($$$), or heading into the states to the closest big box store. I am continuously looking though at local masonry companies!

All that being said, what are you thoughts on my current sketch of an idea?

Thanks for all the help