Vesuvio 90 Replica Build

[Golfpro2301]

Got stand built and will be doing molds and perlite mix today. I am assuming based on how thick this stuff is no need to aerate and its probably not possible.

regarding the inner portion of oven what is easier? A mold or use bricks? I am very handy so either wouldnt be a problem but I dont see many DIY cast projects. I am assuming that is for a reason.

[david s]

I’m not clear on what you are trying to build, in style method and materials, but there are many well documented builds on this site, both cast and brick. Delve a bit deeper and most of your questions will be answered by previous builder’s threads.

[Gulf]

How about a pic of your oven stand and structural hearth. Many times we can spot things that are easily corrected at this stage, but may be difficult to impossible later.

[Golfpro2301]

For some reason photo if stand is to large size. Its a corner stand at 40” tall. Plan was to put 4” concrete on top and leave void in middle for perlite but because I am maximizing my space I poured the whole thing with 5:1 ratio. Plan was to do high temp mortar on top and aides in a few days to get smooth surface and lock in crumbles. After oven built 2” countertop will be on top bringing total height 46”

if I took outer ring of oven to absolute edge I can get a 48” circle. I was going to do a 30” oven floor and build the rest out the same as vesuvio/napolino style with center flue and tiled exterior. For dome I am doing firebrick and will create a styro template as I dont want a perfect dome using IT. Going to shape it as close to casa kit as possible

[Golfpro2301]

Got
photo to work. This is before perlite pour and joint sealing

[david s]

A timber frame, out in the weather will move with fluctuating moisture content. I’d expect it to be up for replacement, if that’s possible, after two decades.
A 5:1 vermicrete or perlcrete slab has a compressive strength of around 200 psi. Standard concrete by contrast has a compressive strength of around 4500psi. Not sure how thick you’ve made your slab or whether you’ve added reinforcing steel, but remember that the strength of a concrete slab is directly proportional to the square of its thickness. ie a 2” thick slab is 1/4 the strength of a 4” one.
So you have seriously underestimated the required strength. It may be possible to mortar some masonry blocks under the slab so it is permanently supported.
Have you calculated or estimated the weight of your oven that the slab is required to support?
I sense your current build could be an accident waiting to happen.

[Golfpro2301]

Timber frame will eventually be sealed up. Last metal frame kitchen I did lasted 5 years in FL. The one I did in midwest out of wood still going strong after 17 years.

The slab thickness is 4” with 3/8” rebar reinforcement. I estimate oven to be around 1900-2100 pounds. I was using 150psi on calculation but I like your numbers better.

the refractory mortar/cement was going to be used on top to create smooth surface and likely only /8” thick.

i have had co
workers run engineering simulation. On weight capactity of stand as well as hurricane force winds and all is good. By doing quick math of psi of perlite mix and oven weight/footprint I dont see this being an issue either

am I missing something?

[Golfpro2301]

Updated
photo showing perlite pour

[david s]

It looks like you've added a further 4" layer of perlcrete. Was that intended for increased strength or increased insulation? Have you calculated the weight of the oven that will sit on top? I'm still really concerned about the durability of your timber frame which will presumably be vulnerable to water seeping in at the paver level. Also concerned about fixings on diagonals. Are they nails, screws or bolts and are they corrosion resistant?
Regarding vermicrete or perlcrete slabs, their advantage over calcium silicate board for insulation is the much lower cost if you mix yourself. The disadvantage is the huge quantity of water required when mixing the stuff. Water is both our friend and enemy, but if the insulation is wet it won't work. This means any vermicrete or perlcrete slab should be dried before building over it otherwise the water will be locked in and its removal by heat will take much much longer. I did a test of drying a vermicrete slab which explains this principle that you might find helpful. Of course the thicker the slab the more difficult the drying.

Vermicrete insulating slab PDF copy.pdf

[Golfpro2301]

The first picture only had 1/2” cement board. Next photo was with 4” concrete. What you cant see is all the cross
members and supports under the top. Engineering analysis has a capacity of over 8k pounds.

no water will come into contact with wood framing. It is sitting on 1” composite boards and eventually all wood will be covered. It is pressure treated ground contact. I had it covered over night and pulled it off today to let it dry. It is setting up well.

I plan to leave as is for atleast 7 days before do anything on top. Ill take a look at documents you sent over. Thanks

[david s]

Ok, thanks for that clarification. So you have on top of your stand 1/2” cement board with 4” perlcrete over that, but no decision on oven plan or weight that your structure is required to hold. Because of the mathematics of volume a small increase in oven diameter results in a massive increase in volume and hence weight of materials. You need to carefully calculate the weight.
Given that you should allow plenty of time to dry the perlcrete, you should use this time to carefully plan exactly what sits on top rather than surging ahead.

[Golfpro2301]

Im going with fire brick build with tile finish. I estimate weight to be right at 2000 pounds. Based on outer ring area of a 48” oven I estimate majority of weight will be around 350sq in or around 6lbs per sq inch

[Gulf]

.......Given that you should allow plenty of time to dry the perlcrete, you should use this time to carefully plan exactly what sits on top rather than surging ahead......

A very BIG +1 on David's statement. Along the lines of what David advises about the size of the oven: In an given space can only sit a certain size oven that can be properly insulated and given a shell that will protect it from the elements. Whether that be an enclosure or an igloo style finished oven. As important as driving the water out of fresh vermicrete/perlcrete, is keeping the water out!

When you decide the size and style finish of your oven, it will be good for us to know the exact dimensions of your stand. That will help us with future advice.

[Golfpro2301]

Easiest way to describe would be a slimmed down vesuvio 80. I plan a 30” floor with a 46-48” exterior. I can put a 48” circle on the stand and it goes right to the edges. I plan use 3” insulation on edges and 4” on top like FB does. One modification I may have to make is depth of throat going into oven

its going to take me at least 3 weeks to gather materials and create dome forms. After how many days do you think I can remove forms on perlcrete I poured?

[Gulf]

Ok. I'm guessing a little here. So it's a 48" square form with a diagonal cut to make it like a "corner build". Yes that may leave you very little room for an entry. One idea is to add some corbels to the front to accommodate the size entry that you wish.