42" corner build, Devon

[Baldywills]

Hi All,

Thought I would commit my build into a thread with pics. This is my second build so hoping to do it quicker and better than my last one which went ok. Certainly making some major changes to the way I am setting up the oven, mainly because I have more space and resources this time around.

The setting is a pool area which had a bit of unused land at one end full of gravel (next to a pool, why would you?) so I have laid a concrete base over the whole area with a view to it being paved but with the obvious addition of an outdoor oven, BBQ and bar. All of this to be covered, due to the nature of the British Weather, by a roof.

The pizza oven will be a 42" Pompeii corner build with polished concrete worktop to the left and to the right with a sink fitted to the right hand worktop. To the right of that will be a BBQ. The blockwork will be covered with reclaimed local Torquay red brick to give it an 'aged' look.

The slab is 10cm thick and as I have a surplus of calsil board I will ensure I use enough under the oven floor bricks. Thankfully I have a huge petrol powered water-cooled brick saw for when I get going on the brick work. Last time out I used a 9" angle grinder to cut all of the bricks and I am grateful not to have had any accidents with it! I figured with the large brick saw (which cost £450 plus I had to drive an 8 hour round trip to collect) it was worth it for safety reasons, and also I am 100% sure I can sell it at the end of my build for the same as what I paid for it. Quids in!!

I plan on polishing the concrete worktops but have also seeded them with different coloured glass particles. This is new to me but I did some trials with the process a few years ago and having bought all of the kit it is about time I used it in anger.

I have just finished the concrete pour so now I can take stock, tidy the area and prep the next stage which will mainly be brick based and post some pictures on this and the UK site.

So far I am very happy with the progress and how it's looking. I am particularly happy with how my formwork ended up as my previous build was a bit crap and very Heath Robinson.

Cheers. Gary

[Baldywills]

Some more pictures of the form and concrete pour

[Baldywills]

And some of the completed slab

[david s]

I’m not sure about your budget for the project, but the polishing of the concrete top might be best left to someone with experience. The larger the machine the easier the process. I’ve done several small jobs, mainly cast decorative arches which I use my 100mm wet polisher for, but for larger areas you’ll need a larger machine. The largest job I’ve done, seeded fro the top like yours, was a 2m2 counter top which I hired a larger dry polisher with a vacuum system attachment.(far less messy than a wet machine).

[Baldywills]

Cheers David, good idea to use a larger machine, I shall keep an eye out to see if I can hire one or buy and resell. I am not too bothered about the mess a wet grinder will make as the area is going to go through a lot of change anyway and the current floor is roughly laid concrete. I don't really want to get someone in to grind and polish the worktop for me as I do want to complete the project myself.

Looking forward to taking the forms off later today and seeing how the sink 'drops' in. Fingers crossed I got the measurements correct.

[Baldywills]

Finished taking the forms off today and had a little tidy up. Will wait a little while before building the dome but have plenty of brickwork to do in the meantime

[Baldywills]

Have managed to do a little bit of brickwork over the last couple of days but am hoping that I should be able to get started on the oven floor over the next few days.

My concrete worktop is fine as a base but unfortunately it was not up to being ground and polished as it isn't hard enough. Lesson learnt for next time (when I do the bar). So this time around I am going to have to reattach the formwork and lay another specialised 30-40mm layer of hard concrete which I can then polish.

onwards and upwards.

[Baldywills]

Am going to starting bringing together the oven floor so started yesterday with the calcium Silicate board. I picked up a special deal on 'seconds' of these 40mm boards, as you can see I have cut two circles which I will lay on top of each other giving me 80mm under cooking floor insulation. I do have enough spare blocks (gazillions of em) to put another layer of insulation on but don't want to raise the oven floor too much. The floor height is currently just a little higher than my elbow and I am sure I have seen somewhere the recommended height is elbow height.

I will use some more of the calsil boards to surround the BBQ but apart from that I have a few spare. If anyone is in Devon (UK) give me a shout if you need calsil boards.

Have to go and work on my beehives this morning but hoping to sort out and cut the bricks for the oven floor this afternoon - in the sun. ☀️

Gary

[UtahBeehiver]

Nice work, ensure the dome sits on the CaSi and not the hearth which would act as heat sink. What are you plans under the CaSi? Do you have weep holes in the hearth? The current recommended practice is to lay spaced out ceramic tiles with weep holes as the base layer under the CaSi.Yes, elbow height is a good rule of thumb.

[Baldywills]

Nice work, ensure the dome sits on the CaSi and not the hearth which would act as heat sink. What are you plans under the CaSi? Do you have weep holes in the hearth? The current recommended practice is to lay spaced out ceramic tiles with weep holes as the base layer under the CaSi.Yes, elbow height is a good rule of thumb.

Cheers Utah,

I must admit I am not planning on doing any of those things you say.

The dome will start on top of a soldier course, so will be using the entire height of the bricks on the outside of the CaSi board and oven floor. I had done this previously with my first oven and didn't get any water issues.

By using the bricks on the outside of the oven floor and CaSi board also allows me to effectively 'seal' the board inside so there is no chance of it becoming waterlogged. I do have plans of a few week holes through the concrete but wasn't going to lay ceramic tile just a bed of light sand for the board to sit on.

To complete the picture I will also be putting a roof over the entire oven so there should be no water ingress. - well that's the plan.

All the best

Gary

[david s]

Unfortunately a considerable amount of heat is lost by conduction if the first course of dome bricks are in direct contact with the supporting slab. Heat rises by convection, but travels equally well in any direction by conduction.
If you don’t want to use tiles to raise the insulation off the supporting slab then perhaps aggregate would be a better solution as it would provide more spaces for moisture travel than sand.

[UtahBeehiver]

You are going through all the effort to place two layers floor CaSi for effective insulation yet having the first row soldiers will negate some of the oven thermal effectiveness. Seriously consider insulating the soldiers from the hearth. Since you are enclosing the oven this lessons the chance of water migration from the hearth. I believe David S is suggesting a possible pcrete base under the soldiers. A 5 to 1 ratio is needed for support, any higher, not strong enough, any lower, substantially higher thermal transmission (K value).

[david s]

You are going through all the effort to place two layers floor CaSi for effective insulation yet having the first row soldiers will negate some of the oven thermal effectiveness. Seriously consider insulating the soldiers from the hearth. Since you are enclosing the oven this lessons the chance of water migration from the hearth. I believe David S is suggesting a possible pcrete base under the soldiers. A 5 to 1 ratio is needed for support, any higher, not strong enough, any lower, substantially higher thermal transmission (K value).

Actually I was suggesting hard aggregate under the floor insulation instead of tiles and as a better solution than sand. I agree that a 5:1 vermicrete under the soldiers would be a good solution. Or perhaps you can use your cal sil offcuts, some of which already cut to shape will fit.

[Baldywills]

Hi Guys,

In response to you both in do agree with some of what you say. There will be heat loss through the soldier course fire brick, obviously the outside of the brick dome will be covered in the normal fire blanket, about 10cm of vermicrete then a render.

I will use ceramic tiles under the CaSil insulation boards as it makes sense to lift the boards off the concrete base but in my mind the soldier course, which is the very first course of bricks should be on a solid foundation base and not on top of the CaSil board as it isn't a solid base and if it failed it could cause the soldier course to collapse. For this reason I am going to set the soldier course on top of my solid concrete base

With the soldier course being on the outside of the oven floor most of the height of the brick will be covered with first of all the insulation board followed by the brick of the oven floor so not too much of the brick will be exposed to the heat and subsequent heat loss.

Hopefully I have explained my reasoning well enough but basically I want strong foundations for my dome.

[david s]

The strength of both cal sil board and a 5:1 vermicrete are both quite adequate to support the dome, at the same time preventing heat loss by conduction. With the insulation encapsulated, damage is prevented, when either cal sil or a 5:1 vermicrete is used. There have been no reports (that I’m aware of) of failure at the under dome insulation. Because of the relatively large area the load/sq in is not particularly large. If the dome is built on top of the brick floor rather than outside itt, the load is spread even further.
Laying the dome bricks directly on the supporting slab encourages conductive heat to travel easily from one dense conductive material to another. Such a large thermal mass as the concrete supporting slab acts as a very efficient heat sink resulting in increased fuel consumption and poorer heat retention.