New Build Pershore

[isolec]

Hi Cannyfradock

Thank you for your kind words re the blockwork. As an Electrical Engineer with little brick work experience it is encouraging to known at least it looks OK. There is a Screwfix in the next town so i guess its an excuse to get out for a bit.

[bookemdanno]

Welcome aboard! You look like your a tradesman, or have previous. Nice work!

Those storage heater bricks cut very easily with a diamond disc on a 9" Grinder.
They chip a bit, so don't cut them in shorts or you get a semi-painful grit blasting of the shins!
Quite a bit of dust too, so a soak probably wouldnt' go amiss, although i didn't.

[faz]

I didn't soak mine, but I did wear a dust mask as the purple dust didn't look too clever! They cut fine with a diamond disk and I used a piece of ply with a 2*1 lip nailed on one edge to hold the bricks while cutting them, rather than clamping them in my workmate, and it was load faster when there were lots of bricks to cut.

[isolec]

Sounds like good advice - thanks both.

[isolec]

Looking at everyones designs, they often put a thermal break between the main body of the oven and the entrance/chimney. However, it doesnt go across the hearth entrance floor. Is this right? Will a thin section of thermalite block be affected by the heat and the products of combustion as it rolls round the lip and in to the chimney?

[cannyfradock]

Isolec....good point.

On my last build I put a 10mm piece of fire-board up against the hearth fire-bricks, then used normal clay bricks up against the fire-board as the entrance hearth. This will keep more heat into the hearth and dissipate any heat reaching the edge of the entrance hearth. The pots of ready-made fire-clay is OK for glueing and keeping the fire-board in place before the next brick goes up against it.

When the same is used in between the internal arch and entrance arch the same will apply plus, the insulation layer and final render usually touches part of the entrance archway so by doing this it will help prevent cracking of the render around this area.

I've used fire-board for this procedure but a slice of thermolite block will probably achieve the same. I have thought of using fire-proof mastic to seal this joint, but haven't got round to trying that yet......I'm still learning!

This is another complicated little piece of a wood-fired oven build and many people haven't done this.....including me on my first couple of builds. It is the correct way to go, but won't affect the performance of the oven( in case any members are starting to panic)

Terry

[faz]

Hi Isolec, I left a thermal break between my arches and also between the hearth and entry. I used vermiculite for the break, but you could equally use thermalite block, board or anything with insulating properties. It doesn't need structural strength but will need to be able to resist the full heat from the hearth.

[isolec]

Hi Terry

I am sure it is worth doing, and as i have a couple of durox blocks left will do it all round. My only concern is durability of the thermalite as items are dragged over it - in and out of the oven. I guess if it is only 10 - 15mm thick and a couple of mm lower than the hearth it shouldn't get damaged.

Steve

[isolec]

Hi Faz

Have you bonded the Vermiculite with anything or is it just loose?

[bookemdanno]

I suppose using something like Quarry tiles over the heat retaining bricks makes it easier, as you can simply cut the Thermolites to match the firebricks used in the oven then tile over it. My build should show where i cut Thermolites to the same thickness as the storage heater brick at the point of Oven entrance, then quarry tiled over.


Thermolites (aerated concrete blocks) won't like being used as a cooking floor, they will break up. You will definintely need a wearing layer.

A simple thin section of block between the oven and entrance may work, but aerated blocks are very fragile. Perhaps Hardibacker board or Aquapanel may be better?

At the oven chimney arch joint i'm going to leave a half inch gap, then force fit some 15mm diameter woven ceramic fibre stove door rope into the joint between oven and entrance arch. Then the outer Vermiculite layer will bridge over, to seal from the outside. I hope that the stove rope will act as a door seal later too. You won't get a better heat break than open space, but some form of seal is needed, hence the rope.

[faz]

My vermiculite is the normal vermicrete mix, which was then tiled over with quarry tiles.

[cannyfradock]

Mmmm.....some interesting differing ways in achieving the same goal. I have seen the picture from faz before and never quite understood it.....now it has been explained it makes perfect sense (sorry Faz...sometimes I'm thick as shit!)

I haven't seen the last oven I built since it has been fired so I'm not sure how the fire-stop in the hearth is performing. On reflection it was 5mm fire-board (which I doubled up on the hearth) but just left the tidy edge(5mm) of the board flush with the hearth bricks, hoping that any small cracks would fill with ash?

Terry

[isolec]

Well up early this am keen to get on with the oven chamber. Sun shining, promise of rain later so need to get moving. Thought i would check with the local Jewson by phone, that they had Fireclay in stock, before driving over, to be greated with "sorry dont stock it any more". Apparently last batch went hard and was scrapped. According to the computer - none of the branches stock it any more as there is no stock code on the system!!

[faz]

I got mine from Kiln Linings as the only bags that Jewons stocked were tiny little bags that would have been a bit pricy. They did have the lime and vermiculite though, so I got them from Jewsons.

[isolec]

Thanks Faz - looks like its on the computer and then back to bed!!!!