Oven built, advice needed

[Pizzaloaf]

Hi newbie here after advice

After having built 2 clay ovens over the past 5 years and them eventually collapsing due to water getting in and the walls only being a couple of inches thick), we have taken the plunge and built a brick oven.

It was essentially built from free/leftover/scavenged and donated stuff so we didn't have proper fireproof cement or firebricks etc but hey work with what you've got eh

So the oven base is a layer of smooth engineering bricks laid on their side laid on a bed of sand. The oven itself is made of from solid bricks which a friend had leftover and gave them to me. They are a buff coloured quite 'sandy' brick which look handmade (the edges are a bit uneven where they have been made with some having a slight rounded edge).

We used a wooden form and built the inside layer (with morter using a 3:1 sand cement mix) then once they had gone off we added the outside layer. The chimney is a piece of clay pipe about 140mm diameter (about 20mm thick)

So once all was ok we took out the form, and as you can see there's some mortar that needs cleaning off (and we need to finish the top 2 layers are the back). Hopefully then it'll be ready for its first firing.

Now having read lots of posts about brick types and mortar types I'm panicking that it's either going to explode or collapse!! One thing I am concerned about is mortar falling into pizzas as it get hot. One thing I've considered is a inside lining of tin foil to keep the food free from falling mortar when we are using it. The other thing is to line the inside with clay dug from the ground (I have quite a bit left over from when we built the other ovens).

We use the oven about 3 times a year so it doesn't get loads of use, but obviously I want to make sure they are safe

Any suggestions/thoughts?

[Pizzaloaf]

Sorry the photo didn't upload last time

I have since fired it and all seemed ok, the only thing I thought was that the vault appeared quite high and keeping heatvat the bottom may be an issue so I was thinking of raising the base with another layer of bricks maybe?

[oblertone]

Here goes nothing ! What you've built (very well) appears to be 85% of a barrel vault oven with a badly positioned flue. These ovens work best if the products of combustion (hot gases) are held in the roof space of the oven to enable heat transfer to the structure; that heat is then slowly released to assist in the all-round cooking process. In your oven you have provided two avenues for this hot gas to escape, firstly via the entry arch and secondly via a roof mounted flue. Your oven will undoubtedly cook pizza as it is, but with a few simple modifications could be made to perform much better.
Firstly the flue, remove it and brick up the hole but don't throw it away.
Secondly you need to prevent the gas escaping by partially bricking up the front entry so the internal top of the new arch is about 60-65% of the internal height of your dome, thus creating a space where the heat exchange can take place. If you then extend this secondary arch forward to the edge of your plinth you can remount your flue on it so you're not working in hot gas.
As to your choice of bricks and mortar, without a complete rebuild it is what it is and will give you endless entertainment as pizza cooking in one of these is pure theatre with a foodie finish.
These are just my thoughts, I sure others will be along with theirs ... Paul