42" corner build, Devon

[Baldywills]

Gave the bricks a scrub, the eagled eyed amongst you would notice the different coloured bricks. The project took so long I used some of my supply of firebricks to line the BBQ. This led to a shortfall in brick numbers for the pizza oven and try as I may I couldn't get the same colour again. I used what I had left to create the front

I do like the paler coloured bricks to work with and they do cut well but as they are going to be on then inside of the dome I don't think it really makes any difference.

Managed to keep enough of the darker bricks to finish the front arch and supports.

[Giovanni Rossi]

Looking good so far.

Too bad about the flue position. You could go straight up by cutting that roof joist and installing header joists. If you decide to do that, not sure you need it in this case, but you may want to add temporary vertical supports to what will be the tail joists before you make the cuts.

As you've already discovered...cleaning the bricks at the end of each work session is the ticket.

[Baldywills]

with pics

[Baldywills]

Hi All,

I have been busy creating the front arches and the smoke chamber and loosely set up the flue for size. Unfortunately I had to put a couple of bends on to make sure it missed one of the roof joist. I haven't cut the hole in the roof yet but as it is due to rain for a week so I shall leave it for now.

I gave the internal brickwork a bit of a scrape off today so it looks a lot better than it did. I will give it a scrub with some brick cleaner acid before I continue with the dome.

I must be cleaner with my brickwork.

The flue is a twin wall 8inch internal. Hopefully it should be up to the job as I do not want smoke coming out of the front.

[Baldywills]

Hi Gary,

"Nothing underneath the bricks, they are laid straight on top of the calsil boards."
Do you mean the dome bricks? ie did you decide to insulate under them, or are you just talking about the floor bricks?

Hi David,

In answering the question from Toiletman I think he meant the oven floor bricks. I think some people use a sand layer to help keep everything level??

I decided to crack on without insulating under the soldier course. No doubt I will lose some heat downwards through the length of the brick but I had already set the bricks in place and I wasn't going to remove them.

Cheers

Gary

[david s]

Sorry, I didn't realise I hadn't answered this question.

The granite is already waterproofed and should last me a couple of years before I have to reapply

Nothing underneath the bricks, they are laid straight on top of the calsil boards.

cheers

Gary

Hi Gary,

"Nothing underneath the bricks, they are laid straight on top of the calsil boards."
Do you mean the dome bricks? ie did you decide to insulate under them, or are you just talking about the floor bricks?

[Baldywills]

Nice kitchen, looking forward to seeing the oven finished!

Two questions:
- Did you waterproof the granite already? I understand you need to impregnate it to ensure you don't get water stains in it.
- What's the material underneath your oven floor, in between the calsil and the bricks?

Sorry, I didn't realise I hadn't answered this question.

The granite is already waterproofed and should last me a couple of years before I have to reapply

Nothing underneath the bricks, they are laid straight on top of the calsil boards.

cheers

Gary

[Baldywills]

So today in the partial sun but harsh wind I managed to get some brickwork done on the front surrounding the landing and casill boards. I am lucky as I have a roof over the top so I haven't had a problem of water getting to the casil boards but it is nice to finally encapsulate them.

I still need to do the transition from the front landing into the dome but it's all planned . I think I will add another pier of bricks to the front to cover the weight of the archway once I build it.

I did a few awkward cuts today which was soooo much easier with my big brick saw. I remember the last time I built an oven (8 years ago) I was simply using an angle grinder for cutting bricks- nearly lost my foot and some fingers a few times.

[Baldywills]

Thought I would take a quick break and tidy up. Have finished the BBQ area and completed a few courses on the oven dome. About to think and contemplate the entrance arch and reveal so thats going to hurt a little. It's one of those things where I know what I want and just have to make it work by many cuts using the big brick saw and small adjustments using the angle grinder.

[Baldywills]

Hi Gary,

If you are still set on laying the first row of bricks directly on the supporting slab, here are a couple of suggestions you might consider.

Firstly, laying soldiers as a first course introduces the problem of creating long vertical joints between the soldiers. Because the most vulnerable part of any hemisphere is at its base (think of an eggshell cut in half), many builds using soldiers use a steel band around the soldiers. This is a difficult operation, especially across the oven mouth and introduces corrosive steel. A better solution is to use two half brick courses instead of the soldiers, so the mortar joints are staggered, eliminating the long vertical joints.

Secondly, if the first course of half bricks is insulating fire brick, rather than dense fire brick, it will insulate the base of the dome very well.

I love the detail on your build by the way. Did you abandon the concrete polishing in preference to the granite?

Dave

Cheers Dave,

Yeah it turned out the concrete polishing was going to be bigger than Ben Hur so I binned the idea and opted for the granite. It is expensive but I could outsource the job so I didn't have to worry about it.

The main problem with the concrete polishing was I don't think I made the mix hard enough and so as I was polishing I was getting grit crumbling off the concrete surface. I only tried to polish one corner with a small wet polisher but even if I could hire a larger machine I think it would have taken about three weeks of very wet work, I simply couldn't afford the time.

The weather is warming up in the UK now so I should be able to get back out on the dome. Will take a look at your suggestions on the soldier course.

Cheers

Gary

[david s]

Hi Gary,

If you are still set on laying the first row of bricks directly on the supporting slab, here are a couple of suggestions you might consider. Because thermal expansion at around 400C is around 0.5%, it translates to about 5 mm/m which can easily be enough to break the bond between the base of the dome and the cooler supporting slab on which it sits. The frequent expansion and contraction cycling of continued use exacerbates the problem. For this reason as well as the heat loss, builders have opted to insulate the total oven, both under and over it. As well as creating an expansion joint between the gallery and outer decorative arch, or between the dome and gallery. Here are a couple of things to ponder.

Firstly, laying soldiers as a first course introduces the problem of creating long vertical joints between the soldiers. Because the most vulnerable part of any hemisphere is at its base (think of an eggshell cut in half). Cracks in domes are common and invariably originate from the base. Many builds using soldiers use a steel band around the soldiers in an effort to reinforce the base. This is a difficult operation, especially across the oven mouth and introduces corrosive steel. A better solution is to use two half brick courses instead of the soldiers, so the mortar joints are staggered, eliminating the long vertical joints.

Secondly, if the first course of half bricks is insulating fire brick, rather than dense fire brick, it will insulate the base of the dome very well.

I love the detail on your build by the way. Did you abandon the concrete polishing in preference to the granite?

Dave

[david s]

Ok. Heat travels in three ways, by convection, conduction and by radiation. It doesn’t care what direction it travels by conduction and will travel faster the higher the material’s thermal conductivity is. The thermal conductivity of standard concrete is only slightly lower than dense firebrick, resulting in heat readily transferring to the very large thermal mass of the supporting slab (heat loss)

[Baldywills]

Having insulated under the floor particularly well, I noticed that you have not insulated under the oven dome bricks. Is there a particular reason for omitting insulation here because a significant amount of heat will be conducted into the supporting slab and apart from the heat loss could cause problems with your granite that sits on top of it, because granite is renowned for not liking heat. It might not be too late to insulate under them and prevent some possible problems before starting the dome proper.

Hi David, I have not sat the soldier course on any insulation as most of the soldier course is not going to be in contact with direct heat from the fire and any heat will have the entire length of the brick to traverse down towards the concrete base which then also has a pretty solid heat sink.

The granite worktop has been cut shy of the dome by 50mm so will be protected from any heat as I plan on having insulation all around the dome in several layers of vermiculite, blanket and covered in a render.

I think I understand the point you are making about heat dissipation but I much prefer the soldier course to be laid directly onto the concrete slab to give a solid construction base rather than sat on an insulation board.

[david s]

Having insulated under the floor particularly well, I noticed that you have not insulated under the oven dome bricks. Is there a particular reason for omitting insulation here because a significant amount of heat will be conducted into the supporting slab and apart from the heat loss could cause problems with your granite that sits on top of it, because granite is renowned for not liking heat. It might not be too late to insulate under them and prevent some possible problems before starting the dome proper.

[Baldywills]

Nice kitchen, looking forward to seeing the oven finished!

Two questions:
- Did you waterproof the granite already? I understand you need to impregnate it to ensure you don't get water stains in it.
- What's the material underneath your oven floor, in between the calsil and the bricks?

Yeah the granite top is sealed and been highly polished, shouldn't have to do it for a year.

I don't have anything between the bricks and the calsil. I have oven floor bricks, 3 layers of calsil sat on the reinforced concrete floor- of which it contains night time storage heater blocks (as heat sink).