Simon's Edinburgh Old 1867 Red Clay Brick Build

[miniadventure]

Hi Folks,

Im starting this thread as you will see from the pictures, I'm using very old clay bricks sourced locally.

I've already built the concrete foundations and also the dense concrete block walls and manged to build a brick arch for aesthetic purposes.

I'm about to poor the concrete slab with metal reinforcements into the left hand side block work, shuttered off with wood and supported underneath with Kingspan. The oven will sit on the left hand side block base.

I intend on laying slabs two 3"x2" concrete slabs on the right hand side, these are very thick old 60 mm concrete flag stones, also dating back to early/mid 1900's. I will use the Right Hand side just for rolling out pizza bases and general use.

I have about 150/170 old Edinburgh Red Bricks that ive been advised are dense clay bricks and i intend on splitting them in have to build the dome.

My intention is to lay Thermalite Blocks on top of the new concrete slab as a base and then try and source Red Quarry Tiles to use as the the Hearth/Oven floor.
I believe these are also made with clay and will withstand the heat. They are aprox 6" x 6" and 10/15 mm thick.

Apart from one other build i cannot see any other threads that have used the the old red clay bricks so im open to advice and help where people can.


The red bricks are not splitting very well with hammer and bolster, so im going to have to cut each bring into half with my Stihl saw.

The left hand side block work measures 900 mm wide and 1000 mm deep.

Based on the smallist measurement of 900mm, once the bricks, insulation blanket and render is taken into consideration (Around 140 mm each side of the dome, made up of 70 mm brick, 50mm blanket and 20mm render)

I think the internal dimension of the oven will measure 600 mm,

The Dome will be 300 mm tall

The entrance arch will be around 190 mm with a throat opening of 305 mm ( just enough for a 12") pizza.



 

[my2girls]

Hi Simon I am also using old red clay bricks as I also sourced them for free , I split mine in half with a bolster and then cut them into a traps zooid shape with a 9" grinder and diamond blade , it is possible to just use the half bricks without cutting but you will use a lot more cement and as you get higher up the dome , the top edges of the bricks will meet leaving a large gar at the bottom edge of the brick leaving a triangle between each brick.
I also used thermalite blocks under my oven floor but I coverd them with another layer of concrete.
I thaught of using red tile for floor but couldn't find any , same with storage heater bricks and ended up just buying fire bricks

[mutteringfool]

Hi Simon, I just used a bolster and hammer, it doesn't matter so much if the back of the brick that is the outside of the oven isn't perfect as by the time you've put the insulation etc on top it's smoothed out. I didn't have the patience to cut/grind each one, obviously gives a tidier looking oven if you do but not the end of the world.

[stevo]

Great looking start!

Btw, that brick photo you sent - thats where i currently live, Arniston, Gorebridge!


Stevo

[smithjames0]

I am interested on how you are getting on with the slab, I think we are using the same design.


James

[miniadventure]

[kipper]

Great build Simon. I really like what you did with the keystone at the entrance. Wish I'd thought of that.

[miniadventure]

Folks, I have a problem with the metal chimney, cracks around the base of it where it meats the render, I think this is because the metal pipe rests directly into the brickwork, maybe expanding and contracting...... Anyone offer advice pls

[cobblerdave]

G'day
Remove the render around the chimney and wrap the pipe in corrugated cardboard from a old box and tape into position. Render back to that and after the cement gets to the first set the cardboard will be soft and easy to pick out. The resulting space around the steel chimney can then be filled with automotive sealer the one designed for exhurst components.
Hope this helps
Regards dave

[kstronach]

Or replace with a insulated twin wall flue, I originally had a single wall metal flue and I had nothing but problems with render cracking. It would be a shame if you applied your finished waterproof coats and it cracked it all!

Keith

[miniadventure]

What if I removed the metal flu pip and replaced with a clay chimney pipe? I have one, it's 6" internal diameter, my hole for the flu pip is 5", so this would have to sit around it, but it is only 13" tall. Considerably less than the current metal one.

Obviously the taller the chimney the greater the draw, but is there a minimum size in height a chimney should be on a wood burning oven? Or could this clay chimney be a suitable alternative that could stop the cracking....

Your thoughts pls

Thanks

[kstronach]

the clay chimney would still get really hot as its uninsulated so it would still cause you problems i think, if you don't want to go down the twin wall route dave's suggestion is the one to go with, the joint can be about 7 to 10 mm around the flue then fill with some high temp sealer! not had any experience with exhaust sealer but if cd says that it will do the job it will be fine, an alternative might be this stuff

www.screwfix.com/p/mapei-mapeflex-firestop-1200-c-high-temperature-sealant-grey-300ml/25153

keith

[miniadventure]

Well i took your original advice keith and bought some twin wall pipe and an adaptor pipe that converts 5" SS too 5" TW. thought id slot the Single Skin part into my hole and then fit the TW pipe, however the adaptor is so tall that the render once reinstated will still meet pipe that's single skinned. Might have to revert back to the original SS pipe and just leave a gap and use mastic to finish the gap. Surely the heat will travel through 7mm of mastic though and still crack the render after the mastic?? thanks for all your help guys

[spinal]

If you can get your hands on some fire rope, wrap the pipe in that and then render. The rope gets hot but doesn't burn, and is slightly compressible, so it allows the metal to expand without putting undue pressure on the render.

[cobblerdave]

G'day
The metal pipe expands at a greater rate than brick or mortar, the expanding metal causes the cracks.
Automotive exhurst sealer is rated to 500c enough for the task of high temp expansion joint. The double skinned chimney pipe is also an excellent way to prevent that expansion. Either way you'll have to chase that mortar and do some rebuilding of the chimney mount.. Sorry no easy fix but it's worth you time to get it fixed..
Hope this helps
Regards dave