38" build in Slovenia

[gorazdr]

Hi,

after finding this forum a year ago I had to start my own build .
Cement block base is 120cm x 120cm (47" x47") and top slab is 152xm x 168cm (60" x 66"). Height so far is 90cm (35.5").

I am thinking of doing 20cm (8") vermiculite concrete for floor insulation. What do you guys think? Will that be enough?

I can get vermiculite V3 (1-3mm) and V6 (1-6mm) which one is better?

Looking forward to your comments.

Gorazd

[v12spirit]

Re: 38" build in Slovenia

Hi Gorazd,
According to the FB plans, 4" of vermiculite concrete will be enough. However, the plans also tell that there is nothing that is too much insulation. You can add as more insulation as you like and the result is a slower-to-cool-down oven, which means a more fuel consumption efficient oven that can cook for 2 or 3 days from a single firing, which is a significant advantage of WFOs. The plans say that you mix the vermiculite with hands instead of a mixer in order not to break the vermiculite and reduce its insulation efficiency. So IMHO the bigger the vermiculite crystals are the better it insulates. This is just my opinion.
I would recommend that you download and read the plans before you start your build. They are so helpful and inspiring, and they are available in this site for free.
Good luck with your build.

[gorazdr]

Re: 38" build in Slovenia

I have FB plans and I know that more insulation is better but I don't know if vermiculite concrete will be strong enough in compression, if I double it's thickness?

I'am also thinking that perhaps I could revise my plan a little and place 3" AAC blocks on the bottom and 5" vermiculite over that. This option is cheaper but it should also work? (AAC is 0.11 W/m2K).

What is optimal oven cooking floor height?

Gorazd

[stonecutter]

Re: 38" build in Slovenia

I have FB plans and I know that more insulation is better but I don't know if vermiculite concrete will be strong enough in compression, if I double it's thickness?

I'am also thinking that perhaps I could revise my plan a little and place 3" AAC blocks on the bottom and 5" vermiculite over that. This option is cheaper but it should also work? (AAC is 0.11 W/m2K).

What is optimal oven cooking floor height?

Gorazd

5-8:1 for the insulation slab. A comfortable height for the hearth is just above elbow...but don't get hung up on a number for the final height, it's a preference thing, not a performance one.

[v12spirit]

Re: 38" build in Slovenia

I cannot expect how a thicker slab would perform, but if It were my oven I would go with your second choice of using AAC blocks underneath the slab.

[gorazdr]

insulation layer complete

I made insulation layer from 3" of AAC block and 5" of vermiculite concrete.
AAC block are really easy to work with but vermiculite concrete was pain in my back

I mixed it all using garden showel as I read I should't use power tools. It sucked water like crazy but I tried to use it as little as posible adding only when I could't mix it any more.

Vermiculite cement mix was 6:1 only the last layer of 1/2" is 3.5:1 because I ran out of vermiculite.



Gorazd

[gorazdr]

My DIY brick cutter

I decided to build my own brick cutter.

I used ordinary 9" angle grinder mounted to my diy linear guide.
Linear guide is made from 3cm chrome square tube and 8 ball bearings.

It is adjustable for height and angle. When blade is at 90 degress you can cut 6.3cm thick brick.

Water cooling of the blade is achived by mini garden water sprinkler. Water is supplied directly from water mains because reusing water often leads to clogs.

Total costs without angle grinder 20? + 2 hours of work.

[gorazdr]

hearth complete

I laid hearth bricks on top of 3/4" of quartz sand.

[gorazdr]

By brick laying technique

This is how I lay my bricks. I have no idea if this is the correct way so please comment.

[gorazdr]

Second row done

After two weeks of bad weather I finally managed to lay some bricks.



Gorazd

[gorazdr]

Entry arch complete

Today I decided I am going to make entry arch. I sketched entry in Corel Draw so that I would't get big mortar gaps.

I dry stacked bricks and they looked sort of OK.


but after I mortared them the gap between two top bricks was to big so i used thin brick wedge to minimize gap. I hope this will work even if it looks a bit off.



I hope I did't post to many photos

Gorazd

[ugnsnisse]

Re: 38" build in Slovenia

Amazing rig you've built for your grinder. A solid build in all.

[stonecutter]

Re: 38" build in Slovenia

Did you cut those keys in the arch voussoirs or was that how the brick was moulded?

[gorazdr]

Re: 38" build in Slovenia

I cut those arch bricks.
Keys? Do you mean black bars on top? They are brick markings.

Gorazd

[Tscarborough]

Re: 38" build in Slovenia

The key to making arches work is to lay up both sides at the same time then cut the keystone (or 2) to fit. You have to be a master mason to be able to pre-cut an arch that will work. I have tried many times and have always had to recut the final 1 or 2 pieces.