Oven floor tiles - appropriate size

[BelgianBuilder]

Hi everyone!

It's with sadness that I have to admit I let my favorite project unattended for such a long time. I think we all know the feeling just not getting to do the thing we'd like to do the most.

Anyway, next weekend we plan to finish the brickwork (of the dome). I have a few questions before winter kicks in.

- I assume it is a good idea to cover the dome immediately with the insulation blanket and then put a waterproof canvas over it, even when damp curing has yet to be completed? Would that help prevent the frost reaching the brickwork in the event it would freeze?

- For the perlite/vermiculite render: what do I use best, perlite or vermiculite? I can choose between different sizes of grains (1,5 mm (0,6inch) ; 3mm (0,11 inch); 5mm (0,20 inch)). Whats conventional wisdom here and is it a good idea to add hydrated lime to the mix?

- Toiletman Thanks for the lead to kachelmaterialenshop, they have a lot on offer! My oven is 34 inches, so for a flue I was considering a 150mm diameter and 1000mm length. But how do I connect the flue to the brick vent? This most resembles the anchor plate I view in different threads, is this the thing I need?

- Building the vent will be for another time, but I am wondering if anyone can link to a thread with a clear explanation of the design? It seems complicated since the arch is curved and you need to build a level base. Probably this is a newby question since no one seems to have any problems with it.

Thanks a lot for responding!

[Toiletman]

Hi everyone!
It's with sadness that I have to admit I let my favorite project unattended for such a long time. I think we all know the feeling just not getting to do the thing we'd like to do the most.

Same here: other obligations and winter weather has paused my build as well. Planning to do some indoor molding work during the Xmas holiday.

Anyway, next weekend we plan to finish the brickwork (of the dome). I have a few questions before winter kicks in.

- I assume it is a good idea to cover the dome immediately with the insulation blanket and then put a waterproof canvas over it, even when damp curing has yet to be completed? Would that help prevent the frost reaching the brickwork in the event it would freeze?

Not sure if this response is still in time, but for what it's worth: I've left mine without the insulation and under a tarp. But for me the mortarwork was done well before it started freezing at night. If you still have wet masonry it might indeed be good to insulate it and possibly provide a heat source inside of the oven as well (ie. builders lamp). Make sure to test that it doesn't get a risk of fire ofc. I'm not sure if you would like to use the high temperature blankets, or just any kind of insulation material, as you might not want your final insulation to soak up any excess moisture in case of small leaks.

- For the perlite/vermiculite render: what do I use best, perlite or vermiculite? I can choose between different sizes of grains (1,5 mm (0,6inch) ; 3mm (0,11 inch); 5mm (0,20 inch)). Whats conventional wisdom here and is it a good idea to add hydrated lime to the mix?

Afaik you can exchange perlite for vermiculite 1:1 on volume basis. Afaik the current best ratio's are 10:1 vermiculite to cement for insulating concrete, mixing in water until 'the right consistency'. Traditionally it was 5:1 I think. In that 10:1 as mentioned you can exchange perlite for vermiculite as wanted. I'm planning on going 5:5:1 vermiculiteerlite:cement. I went with the 0-3mm vermiculite.
I'm sure there's more people that will add their €0,02.

- Toiletman Thanks for the lead to kachelmaterialenshop, they have a lot on offer! My oven is 34 inches, so for a flue I was considering a 150mm diameter and 1000mm length. But how do I connect the flue to the brick vent? This most resembles the anchor plate I view in different threads, is this the thing I need?

- Building the vent will be for another time, but I am wondering if anyone can link to a thread with a clear explanation of the design? It seems complicated since the arch is curved and you need to build a level base. Probably this is a newby question since no one seems to have any problems with it.

Have a look at my build thread. David A s provided some very helpful comments on how to build the vent connection yourself. I posted some sketches of how I understood his design and that's the way I'll go. There's also some idea's on how to connect to the gallery. daidensacha also did a very nice job with his design. basically casting two parts to first make the curved area flat, and then put the square to round connection on top of it.

[daidensacha]

Hi, I had similar questions about what sizes of the vermiculite and perlite to buy in Germany for my insulation. david s has a lot of experience with it and was really helpful.

V-P-crete
Here is what I used for my v-p-crete insulation mix over my dome. Note I also used ceramic fibre blanket over the dome before adding the v-p-crete but my goal was to retain heat for days to use the oven to cook other things the days after cooking pizza.

• 5 parts vermiculite (2-3mm)
• 5 parts perlite (2-6mm)
• 1 part portland cement
• 4 parts water (added 1/3 at a time and hand mixed in bucket or barrow) (in the end this was not fixed and I added water until it felt right by touch)
• 1 (generous) handful of clay powder per litre of cement added

You don‘t have to add clay powder but its not expensive, and i found it helped when pressing the wet v-p-crete over the dome, with the sticky factor to hold it together. I basically put handfuls at a time in rows, placing and pressing the handfuls in place before adding the next.

Arch vent
Over the arch I considered cutting and cementing bricks (I used schamotte) over the arch to build up a flat platform on which to mound my custom pre-cast vent. In the end I simply cut some formwork to sit on the arch flush with the top, and then filled it with refractory concrete. It was a quick and easy solution, done in a couple of hours. I documented with images in my oven thread, its very simple.

Casting the vent, if you want to do that is a process that takes a bit longer, with several steps. I did it so I could create a smooth transition from the rectangle vent in the arch to the inner 200mm diameter of the flue. The goal was to have a clear path for the smoke. I have to say it works like a charm, is like a vacuum and sucks 100% of the smoke directly up the chimney flue. While I cast my vent separately, ( before i even started on the oven), there’s no reason you couldn‘t apply the same technique to cast one directly in place on the arch. Simple need to make a form from 5:1 or 7:1 vermicrete, that would be the shape (make a block, then carve it back to the shape you want your vent to be) of your inner vent (this is scraped out after casting the refractory concrete around it). Then make up some formwork around the form, leaving space between it and the form to ensure you get a thick enough vent wall. Fill it with the refractory concrete, and wallah. When the concrete is set, scrape out the vermicrete and you have a vent gallery.

My alternative before deciding to cast my own vent was to brick it up, cutting the inside of the bricks that would be the inside of the vent gallery. I have no experience doing it this way.

I documented with lots of photos throughout the process of making my oven, if your looking for ideas, or something more visual so you can work out what works best for you.