I am about to start my first build, I hope to use the plans I found on the net here there is the video to show it made here. I want to make mine without the centre divide on the base, I will replace it with a lintel.
As you could imagine I have a lot of questions
The first one is about the base, the plan is 156 x 132 but does not specify a thickness would 10cm be ok?
G'day Ask away you have quite a " brains trust" of people on here. There all first time oven builders and will answer you questions in a way no " professional can..... They have been in your position Regards dave
In the video the slab of concrete on top of the breeze blocks is held in place via the metal work and the centre column, I am going to replace the centre column with a lintal. The slab just doesn't look very well fix there, what do you think? How thick do you suggest the slab should be?
How thick do the bricks need to be cut? I am trying to work out the width and depth of the slab, if the Internal diameter of the oven is 90cm Brick ???cm Insulation 5cm Vermicrete ?cm Render 1.5cm? Overall minimum width cm
G'day Bricks are usually cut in half and the " cut " side goes to the outside. Firebrick are usually a uniform 125 wide 230 long and can be of various thicknesses 35/50/75 mm. Commons have no standard but are usually 10 mm shorter in width to account for mortar joints around a corner. Commons can't be layed in a herringbone pattern on a hearth floor because of this. Pearlite/cement need only be 30 to 50 mm in depth over blanket insulation. Regards dave
Internal diameter of the oven is 90cm Brick 11.5cm Insulation 5cm Pearlite/cement 5cm Render 1.5cm
Overall minimum width of the slab 136 cm?
Slab size width 1.4m x length 1.5m
Does this sound normal?
Well insulated oven, James - "normal"? Well, it raises a point I've thought of since my build, and that's damp ingress from surrounding exposed floor slab. Not only does rain hit the projecting horizontal surround, it drains off the dome as well of course. If (and I'd welcome ideas from others through your thread) this is a problem, there may be something to be said for having the brickwork right to the edge of the floor (the slab you build the oven off - let's call it the floor) all round and the insulating/weatherproofing jacket overhanging that edge, so rain falls harmlessly away. A bugger cutting the paving slabs/shuttering round of course, but who said it was going to be easy?
Anyway, regardless of all that, bear in mind the floor can be bigger than the size of the foundation slab down on the ground and consequent brickwork dimensions... your floor can 'oversail' the top of the supporting brickwork as long as it's well supported by lintels near the edge. I mention this for two reasons: 1) regardless of whether you cast a floor in concrete or use pre-cast paving slabs, it's handy to have a bit of 'toe room' overhang, particularly at the front and 2) if you do use paving slabs, you don't necessarily have to cut them down to a size, let 'em overhang.
I have not got any pictures of the first part of the block work, but it rained and rained, I ended up using a gazebo. I have been working by myself so I had to improvise when it came to moving the lintels around. I used 50 blocks and 2 lintels 1500 x 100 x 130mm
Do you think there is enough support when I cast the hearth?
Do you think a 4" hearth will be thick enough? I am planning on putting thermalite blocks on top.
G'day 4 ins is perfect because the steel is then incased in cement and is 2 inches from any surface. The alkaline nature of cement preserves the steel from rusting. If you did make it thicker it would be a waste as it's not that wide a slab and you wouldn't need any more strength. Regards dave