Mortar

[Lozbian]

Hi there newbie here, I'm building a barrel vault oven and am about to do the outer skin on my oven , the question I have is what mortar mix to use with the handmade bricks I'm going to put on and also would it be okay to point up with normal mortar as I've used a light creamy colour on my oven base ....and if i could upload a pic i would but it's not letting me

[Gulf]

Are you using the Share Photo button (the camera icon) in the message box? One of the issues that many have is that the pic is too large. If that may be the case, try to reduce the size of the pic.

[Lozbian]

Thanks for the help gulf

[Gulf]

Normally, I would say "yes", you can use general pupose mortar on the face brick. But, I don't see any room for insulation between them and the heat bank?

[Lozbian]

Ahh i see I thought the second layer of clay brick would act as say a render, hmmmm time for a rethink ....what would you suggest ?

[Gulf]

Barrel vaults are not really in my line of experience. However, I do understand the basics. Without the insulation separating the heat bank from the exterier brick, it will take massive amounts of wood and time to heat. Also, there will be a rapid heat loss after the fire goes out. Do you have any under floor insulation?

[Lozbian]

I see , yes I have ceramic silicate board under the hearth , I was thinking maybe to just render the vault using insulation blanket etc instead so that'd mean taking one layer of brick off that I laid today , but that's no big deal while I'm at this stage !?

[Gulf]

That may be an option. But, vaults with the high vertical walls also need some type of buttressing. I would take that bottom course off and rack it out about 3/4". Rack the next course also. Do a third course if necessary to have room for 2" (50mm) of rigid insulation as you have under the floor. The outer layer of brick should fit tight to the rigid insulation. Save the banket for going over the arch at the top. Forget about arching the face brick. Keep going vertical until you get above the heght of the heat bank. Then tie the two outer walls together across the top with some reinforcement bar. From there, you will probably need to build some type of roof over this oven imo.

[Lozbian]

Hi again , thanks for the input . Forgive me for asking but what does rack it out mean ? Being from the UK it might be a translation thing !?

[Gulf]

Sorry about that. I probably should have used the term "step" out the bottom courses. It's much like what is done at the crown of a chimney or brick column. I am having internet issues at the moment. I will try to upload a pic when I can. Also, you can place small rebar in the bet joints of a few courses to strengthen the outside wall to help against the lateral forces.

[Lozbian]

That sounds good ....be good to see a picture !!

[Gulf]

I'll post a pic and/or a diagram when I get back home to the desktop if my internet service is back up.

[Lozbian]

Much appreciated thankyou

[Gulf]

Here is a look at a chimney crown. In this one, three courses were stepped out. You can do the same at the bottom of your outside walls to allow room for rigid insulation board. You may not have a full 50mm at the very bottom but, get as much ridgid insulation as possible. ( you can cut the bottom two brick courses to allow for more room.) The rigid insulation must be placed before laying the outside wall. That way it will be firmly in between the two walls. The upper courses of the vertical walls is where the lateral forces will be the strongest. It looks like you are using about 1/2" mortar joints. So, 3/8" rebar should lay in the bed just fine. Bend and lay one rebar in in atleast each of the top two courses of the vertical run. That should help with the the lateral forces.I would normally prepare a diagrahm to explain but, I am out of time to do so.

There are others who can further explain what I mean or maybe offer some better advice. I hope that they will chime in. I will be battening down the hatches for this next storm. After that, depending on where it strikes land, and it's strength, I may be off line for a few more days.

Good luck with the build.

[Lozbian]

That's great I understand what you mean , many thanks for your input , you've saved me from certain heartache ....hopefully get a picture up when I'm done