How many fire bricks for my dome

[my2girls]

Hi

Can anyone help me with calculating number of bricks required to build my dome please?

My oven diameter is 810mm
Height is 405mm
Arch is 405mm wide
Arch is 255mm heigh

Bricks I will be using measure 230 x 114 x 64

Thanks

[chas]

Hi, and I think you'll find the problem with estimating is wastage.

I just had a look at my progress pics - ukwoodfiredovenforum.proboards.com/thread/1983/norfolk-build - where it seems I used 38 whole bricks (wedge cut to make neater ring, less if left whole) on edge to form the floor surround, then two rings of 21 half-bricks to start the dome followed by 9 diminishing courses of halves and thirds starting with 21 for the dome itself.
I found I needed to pick over the cut bricks to get just the right one... and there were a lot in the barrow unused. You'll be lucky (or more careful than me) if you can estimate to the last brick, but that suggests 115 bricks cut into pieces - if you make no allowance for the diminishing number per course as you go up and rejoice in a surplus to make a choice from.

This is just the dome. The fronting brickwork is so individual I've not tried to work that one out but it looks like another 75 - 100 in my case.

Not sure that helps you all that much, but it's a start...

Chas

[my2girls]

Hi chas

Just looked at your build thread ,

Wat bricks did you use to build your dome and wat bricks for your oven floor?

I'm struggling with the decision as fire. Bricks are a bit out if my budget

[chas]

I used old soft reds - as I was sticking them together with clay for the dome and lime mortar for the other brickwork, I figured (rightly or wrongly) there was little point in using a brick that was harder than the stuff joining them. Reds are also easy to cut with a club hammer and bolster, and can be accumulated free from various sources (gumtree, round the back of mates' garages, skips, front gardens) until you have enough. I think it pays to be consistent and not mix hard and soft bricks.

The floor could also be made from soft reds if you pick the choicest from your collection so as to make a nice even floor with as few gaps as poss. As per forum suggestion, try arranging them on an angle to the entrance to minimise 'steps' further - makes sweeping ashes and scooping up pizzas easier maybe. I made mine from pamments - which here in Norfolk are unglazed soft red floor tiles either 9x9 or 12x12 and about 2" thick, but that was just because I had them.

Chas

[my2girls]

Hi chad thanks for that
Do your soft reds have the indentations like a London brick ?
Also have you had any issues with bricks cracking ?

[chas]

Some did have indentations (frogs) and some didn't. I don't think the lack of a frog - sometimes thought to add strength to the bond in brickwork - makes much difference in our oven builds, though filling the extra space in the joint does use more clay/mortar.

I hadn't noticed any bricks cracking at the point where I rendered over the dome. I would guess any hairline cracks in the dome now are most likely from joints - but of course they're concealed by the render now...

We do, of course, get a bit hung-up if cracks appear. CobblerDave explained to me that in a wet clay joint, the water driven off as steam if fires are lit before the clay is fully dry (and who has the patience to wait for that?) is enough to push a joint open - but it all seems to settle down again.

Anyhow I'll post a pic I found by way of perverse reassurance. There's cracks - and cracks!

Chas


ps click on the image to see it full size

[miniadventure]

Hi Folks, im struggling to split the red bricks with a hammer and chisel, is there a technique? 

or maybe im using the wrong type of chisel, 

[cobblerdave]

G'day
That's it alright. Would help getting a bigger hammer, a home handy mans is a little light.
Place the brick on some soft ground or a doubled over piece of say old towel,thick and soft. It allows the brick to flex and split in the right spot. For a bit more accurate cuts, pre cut the outside of the brick with an angle grinder then it should follow the cuts.
Start a thread of your own and Ill happily follow your progress( a few pics would be nice)
Regards dave

[miniadventure]

Started my own post as per Daves advice. :-) Its called Simon's Edinburgh Old Red Clay Brick Oven.

Cheers

Si