Finally decided on 32in castable dome

[Mullster]

Kvanbael nice to hear from you. I did think a few times about the LEGO bricks - wasn’t sure I could find 45 identical ones in amongst the avengers and Batman sets of my sons!
I did have a moment this weekend where I thought ‘there really is only one way to go now - no going back!’

[aaronpizza]

aaronpizza yes I am planning to render the blocks but not as an immediate priority - think I’ll leave that until the first pizza has been tasted unless anyway points out a good reason not too!

as for the clay to be honest I only starting looking yesterday. I was thinking to post a question about whether some of the fire cement products are the equivalent or not. I think I did find 20kg bags of fire clay for about £30.

What about yourself?

No luck finding any "builders clay", tbh I feel like I'm looking for the wrong stuff :P Am I looking for a slab of clay, or a powered mix do you know ?

[UtahBeehiver]

Powdered clay. Try where Brickie go to get there supplies. Sometimes pottery shops will carry it at a premium price

[Mullster]

Some good progress today - managed to finish the stand ready for shuttering (I think that’s the right term?). I think my stand could have been a touch straighter and my mortaring skills definitely need some work - but it all seems solid - and it feels like the hearth will forgive little imperfections. Plus rendering the stand later will also hide any off bits.
Looking forward to the next stages!

[Mullster]

Really feeling awesome about this project now! Back to woodwork today (which is my favourite) framing out the stand and getting ready for the concrete hearth pour. Found it quick work today. I still have the outer frame to make but have the materials ready for that.
realised that by putting a layer of plastic down before the pour not only will it help the concrete set harder (according to the advice I’ve read on here) but also will mean any gaps around the frame on the inside won’t matter.
I’ve deliberately set my boards slightly below the level of the walls so that the hearth ‘sets’ that middle wall which creates my 2 storage compartments in place.

[Kvanbael]

Cool!

Note that you'll be pouring several hundreds of kilo's of concrete, so make sure the woodwork structures is sturdy enough to carry, let's say 10 people.

Plastic film is common when pouring floor-slabs, because the soil will draw a lot of water. This construction won't draw as much. You can use plastic, but note that any wrinkles will make impressions in your concrete.

[Mullster]

Kvanbael you've got me wondering about the weight - think I’ll do some reinforcements!

[Mullster]

Kvanbael just found a weight calculator - looks like approx 477kg - so maybe 6 people

[Mullster]

Cool!

Note that you'll be pouring several hundreds of kilo's of concrete, so make sure the woodwork structures is sturdy enough to carry, let's say 10 people.

Plastic film is common when pouring floor-slabs, because the soil will draw a lot of water. This construction won't draw as much. You can use plastic, but note that any wrinkles will make impressions in your concrete.

Thinking I’ll only put plastic on the bottom then and not up the sides of the frame

[Mullster]

DavidS a question please. Am I right in thinking that instead of foamglas and casi I can create an insulation layer using a vermicrete mix for underneath the fire brick floor? My hearth will be poured next Tuesday and just thinking about acquiring the next set of materials. I know plenty of people use the foamglas and casi - I’m guessing because it’s a cleaner finish (easier to level)?

[UtahBeehiver]

Up to you and budget. P or Vcrete requires abt double the thickness for the same K value but quite a bit less expensive than high tech insulation (CaSi/AlSi/FoamGlas) also foamglas will not absorb or transmit water.Do search and research blog.

[aaronpizza]

DavidS a question please. Am I right in thinking that instead of foamglas and casi I can create an insulation layer using a vermicrete mix for underneath the fire brick floor? My hearth will be poured next Tuesday and just thinking about acquiring the next set of materials. I know plenty of people use the foamglas and casi - I’m guessing because it’s a cleaner finish (easier to level)?

I am going to do the 4 inch of V.crete myself the casi board is far too expensive!

Over 4 inches has diminishing returns - So I've read

[UtahBeehiver]

Not entirely true. 4" pcrete/vcrete equal to abt 2" of CaSi or equivalent which is the minimum suggested thickness for high tech insul. 4" of high tech insulation I would agree on diminishing returns but not pcrete. But it also depends on what you want to do with your oven. Pizza one night or long term multiday cooking.

[Mullster]

Progress pics from yesterday

[Mullster]

Right guys - due to the site hack many of the recent posts on this thread have been lost so I’m going to post a bit of info bringing you back up to speed with my build. I’m conscious that this site provides a great amount of value for me with a community who have experienced it all before and those who are going through it at a similar time and I love the fact we can ask questions of each other as we go along. If I miss detail out in this catch up please just ask.