Advice on new small Pompeii oven

[Bandit]

Weathers improved, managed to get more firebricks and started building my oven ! Hoping to complete by my little daughters birthday at end of June to serve pizzas to hungry kids.

I am not great at DIY and I built base with sleepers with concrete lintel and made insulating base with vermiculite concrete.

I have a mix of splits and full size firebricks. I have cut full size bricks and put them on vermcrete base with builders sand to level. I realise my cutting is nowhere near most builds on this site and .....

I have small gaps between the 1st layer bricks and edge bricks at base (see photos)

I have a 4 tubs of heatproof screed https://shop.vitcas.com/hps-heatproo...SABEgKYzvD_BwE which I was going to use as mortar and to make firebricks for awkward areas near flue.

I have looked on Forum and most people seem to lay bricks on fireclay/sand mix - is it okay to lay on small layer of sand directly on vermcrete base or would it be better to put a layer of refractory heatproof screed and lay base on that?

Any advice on the gaps at edge of base where they meet 1st layer FB- can I fill these with heatproof screed ? Or should I use small scraps of firebrick ? Or combination


Based on the no of bricks I have and size of my roasting pan and other builds I have made a rough plan.

Not sure how how I am going to make arch or area around flue yet

[SableSprings]

Always exciting to get started on these projects! In looking at your pictures, I couldn't tell if you have those sleepers on a concrete base. My concern is that you might get some sinking as you add weight on the top slab (and as the ground gets wet). Just a thought...

As to the gap, don't worry about that. It will fill in with ash and normally we advise a gap the width of a piece of cardboard to allow for expansion of the cooking floor anyway. You will want to reorient your first outer course of bricks. You want a soldier orientation (narrow side in) rather than the sailor orientation (wide side in) that you have now. Since your next courses will be 1/2 bricks laying flat (wide side down), they will need to have the wider base (11-12 cm) provided by the soldiers. Hope that makes sense.

For laying the cooking floor bricks down, sand mixed with a little clay simply helps to let you level (and stabilize) the floor bricks. You don't want to attach the floor bricks to the underlying vermicrete base with scree or mortar since during oven firing the floor needs to be free floating to allow for some expansion.

Just one other thought here...many people choose to use the splits on the cooking floor, since they heat up faster (and are less expensive). I used full size bricks for my cooking floor as you have laid out and am happy to have more retained heat for baking 20-30 loaves of bread (in 2-4 loads). Worth mentioning here simply because you might find yourself wondering where you are going to use the splits in the dome...

If you look at my build, you'll see I went with a piece of angle iron and a rectangular opening instead of an actual arch for my oven entrance...certainly was simpler at the time . There are many terrific builds with well documented arches and flue/landing areas in the forum, so don't fret...lots of help available for you here.

[Bandit]

Thanks for advice Mike

the sleepers are on paving slabs and breeze blocks with mortar in between - will hopefully hold
Pleased I don’t have to fill gaps between ende of floor and 1st row dome bricks.

I will try soldier course - was put off by other posts that this might need buttressing

was going to put an extra inch or so of my refractive screed around Dome bricks to increase thickness before insulating layer - is this a good idea, or will this just be unstable as one large layer with no gaps for expansion ?

wanted a decent floor and going to put in flue with damper and hopefully make an insulated door so I can slow roast/ bake in the oven ( just aiming for one or two loaves ,!)

i am hoping splits will allow me to make upper dome with less gaps - they are a lot easier to cut

I’ll post pictures next week

[SableSprings]

Glad I could help a bit and good to hear your foundation will be stable. The soldier course actually gives you more wall thickness and therefore less need for buttressing than doing a narrow footprint sailor course. Think of the dome pressing down and out. If you stand a brick on end and push the top of the wide side, it will tip over much more easily than trying to push it over using a narrow face. The difference is going against a wider base, which is more stable. I'm not sure about the other posts, possibly they were not using the correct terminology. I think if you start looking at other successful builds, you will see those that use full base bricks do so using the soldier course. As I mentioned earlier, the other reason to do this is that the next course will be done with half-bricks and you want the 11-12 cm (4.5") length fully supported by the row below it (plus mortar in the wedge as the dome curves inward).

I used a pre-made refractory mortar and did not cut/shave angles on my dome bricks...just cut them in half. The result on the inside was having a bit more mortar showing than if I would have done more shaped (tighter) joints. It has made absolutely no difference in the performance of my oven, but I did end up using FAR, FAR, MORE of the pre-made refractory than I'd planned (filling up the widening gaps on the outside as the dome closed). My point is, that IF you have some screed left over after completing the oven, arch, and flue gallery...by all means spread the remainder over the dome bricks for a tiny bit more mass. I'd honestly be amazed if you had enough to add "an extra inch or so" over the dome. The expanding dome would probably crack a thick layer of screed, but it would not matter. When the oven cooled back down, the oven returns to it's smaller size and all the cracks come back together. That's the beauty of the dome structure...its extreme stability and ability to handle expansion/contraction forces pretty darn well.

Don't know why you'd need a damper...the door fits against the oven opening and closes off the heat rising out the flue. For baking, you'll fire the oven, rake out the ash and any remaining coals, close the oven up with the door to equalize the inside temps, then when you reach baking temps...you bake. Don't know where a flue damper would be needed.

Again, hope this diatribe helps...

[UtahBeehiver]

Mike gives some great advise. The only thing I will add, is a picture showing the nomenclature of brick orientations. I agree with Mike that the if you are going to do a vertical first course it should be a 1/2 soldier. A full soldier increases the outward pressure form the dome and 'may" require bolstering. The second course should be a 1/2 header. I only mention this so future builders can use the correct brick orientation when they post a thread and that we are all on the same page.

[Gulf]

I included a damper in my oven. It is absolutely not necessary. Soldier and sailor courses are hold overs from before the advent of the IT. You can go vertical with 1 or two courses of stretchers just as easily. imo.

[Bandit]

Think I made my base too small !! I made it based on wall 1 Brick thickness + 1/2inch

I estimated the insulating blanket and vermiculite layers take up at least 3-4 inches ??

if I use 1/2 soldier my insulating layers may be outside my base.

my oven is small compared to most builds on this site (24 inch internal diameter and 16 inch dome height)

Do you think I should stick with previous planned brick orientation (thinner wall) which will give me room to fit blanket and vermcrete &render or
go with thicker walls and my insulating layer will not be on the base.

[Toomulla]

I would drill and epoxy some pins into the edges and pour an extension to the base

[Gulf]

The weight of your oven is setting firmly on the stand. The insulation layer does not weigh very much. And it will only be projecting over the form for a short distance. So, you could do as Toomulla advises. Below is what I did for the exact same problem. My forms were still in place so I just added more for a cantilevered concrete pour. It doesn't have to be perfect. I rounded mine for another purpose. However, to cantilever, you will need to carve out some of the p/vecrete layer for the concrete to sit back on the stand.

[Bandit]

Thank you for advice - I was going to use angle bracket supports attached to sleepers/vertical supports and extend the base. It only has to support a small area of insulating vermcrete and render - so should hopefully hold.

[Bandit]

Managed to complete a few rows today

[UtahBeehiver]

As you go up in courses, beginning about the next course, unless you bevel the sides of the brick, you will start to see what we call an "inverted v" mortar joint. The "V" gets progressively wider as you go up. You do not have to bevel the entire depth of the brick, only where the two opposing brick overlap. I have attached a couple pics to illustrate.

[Bandit]

Thanks for the advice Russell
what is the best way bevel the bricks ? I only have angle grinder and was thinking of using the splits for rest of the dome
trying to work out how to cut bricks for oven opening/vent landing at the moment to try and lock in the first few rows

[Bandit]

One of the few plus points of lockdown was TIme to finish half completed projects.
Celebrated Father’s Day with the first newspaper only curing fire and beer !
if the oven survives - It’s pizza next weekend !
and render and finishing touches a few weeks later !

Thank you everyone for posting builds and all the amazing advice on site