Boogie’s cast 37inch WFO Hawaii

[Boogie-D]

Aloha gang... update:: so I really appreciate all the help and feed back with my build... my biggest concern has been securing the brick for my oven floor.... I doesn’t look promising for me to get the pilot dp super duty bricks shipped to me in Hawaii from Los Angeles... however, as many have pointed out, they use regular light duty clay fire place bricks for there oven floor.... I can get this type of clay fire place brick here in Honolulu... so if this is a viable back up option for my oven floor then I can begin to build my stand and concrete table...

I’ll be going with a 4 post base of cinder blocks acting as sono tubes... no floor slab... and no walls... just 4 concrete corner post... similar to neils flying saucer .. I’ll get started and going with this soon... we have a lot of rain in the forecast (dumping right now)... the holidays are upon us... and I have a bunch of bookings this week... also I need to get a picture downsize program for your site... I’ll keep you updated on stand progress and if I can get the super duty’s.. Merry Christmas!!!! mahalo

[Boogie-D]

Aloha FB crew... thanks for all your help and input.. and thanks to all who have shared there journey... I have been reading like crazy... there so much info here sometimes it’s hard to find the info and then there so much info it gets confusing... but I am thankful and thinking through the process... absorbing all the input... and trying to make the best decisions... part of my reasons for being here is to really help other builders in the islands find the supplies they need to be successful... the best Christmas present I got was the news my friend will help me ship the Pilot DP super duty fire bricks to Hawaii... very stoked on that...

I can get the super duty bricks in 12x12x3 and 18x18x3 sizes.... it makes sense that I design my oven and oven floor around these sizes... to eliminate cost, cutting, shipping, and waste... these dimensions leave me with 36” and 48” layout options... for my oven floor I am leaning toward just 4 @ 18x18 fire bricks and cutting out a 36” outer diameter out of these 4 bricks.... thus creating an inner diameter of 33 1/2” -,34”....

david s what do you think? smaller than my original 37inch concept... but cost efficient and waste efficient? And a question for you sir. What’s is your recommended thickness for casting the home brew dome? 2 inch? or 2 1/2 inch?

I get conflicting info.. I was under this impression please correct me where needed

2 1/2 inch cast home brew
2 inches @ 2 layers of 1 inch CFB
2 inches perlicrete
chicken wire
2 inches perlicrete
1 inch stucco

MAHALO!!!

[david s]

Brick builders are really stuck with a 4” thick dome because of the bond required between the bricks. Some have tried to mortar thinner bricks and found the mortar fails because there is insufficient width in the joints. The same applies if you were to build a house with joints that are less than 4”. Because a cast does not have mortar joints, or very few if cast in a few sections, this limitation does not apply. The thickness of the casting needs to be thick enough to make it strong enough but also thick enough to provide sufficient thermal mass for retained heat cooking. Most cast manufactured ovens are 2” thick and this provides sufficient thermal mass combined with reasonable heat up times. As your floor bricks are 3” thick you may be better off with a 2.5” thick dome.

Is there a reason you want chicken wire in between the two vermicrete layers? As insulation a lean vermicrete is very weak, strength is not required there and adding conductive steel wire to the layer is counter productive IMO, others may disagree.

[Boogie-D]

Thanks David... I think I’ll go with the 2 1/2 inch thickness for my dome... I’ve read so much info it’s getting confusing... and people just do things differently... I am under the impression if my outer diameter is 36 inches and I am casting a 2 1/2 inch dome... this would make my inner diameter 33 1/2 inches correct?... this way the cast goes right to the outer edge of the floor bricks and when I insulate with the CFB it will cover the dome and floor bricks in one shot..?? Is this proper?

david s I am surprised you didn’t chime in on my 4 @ 18 inch x 18 inch floor bricks... I’ve been thinking... these 4 big bricks are only a total of 35$ cheaper but the dome would basically sit squarely on all 4 bricks thus creating the dreaded replacement issue you mention... if I went with 9 @ 12”x12” floor bricks the dome would sit better on the bricks/ with more seams... but there would be one center brick that would be easier to replace and the others bricks appear to be easier to replace according to my sloppy sketch... David these floor brick are the biggest challenge I face in Hawaii... it’s been a real pain in the arse!! what floor bricks do you recommend for me.. either 4@ 18x18x3 or 9@ 12x12x3... thanks I can’t wait to put floor bricks behind me and to get them on the barge...

I have chose to use perlite versus vermiculite for my insulation needs as it is readily available in Hawaii, I believe it is more water resistant and is stronger then vermiculite.... but I can get vermiculite... because both the perlite and vermiculite at those 10:1 insulating rations make for a week material I was under the impressions the chicken wire would give it some strength... my plan was to mold and shape my chicken wire first... then cast 2 inches of perlicrete, place the chicken wire on, then cast 2 more inches of perlicrete all in one shot... ??

I really appreciate the advice David as you are one of the best... it’s been raining everyday so my wfo work site is all muddy... and I have rubbish there that needs to be burned that’s all wet too... I am anxious to start my base but need to wait till everything dries up... for now i just continue to read and think it through... and most importantly my priority is to place my floor brick order by next week Monday... Happy New Year everyone especially mark, Russell, NC man, and David I really appreciate all your input on my build... CHEERS!!!!! \uuu/

[Boogie-D]

Some of the building stuff I am getting ready

[Boogie-D]

[Boogie-D]

this is a lava rock oven in Kona... I really like the finished look of this oven... we have a lot of lava rocks and in the pictures you can see we have a lot of faux lava rock pavers to cover the cmu base... I also have access to a bunch of free granite... so this is the look I am going for on the entire out door kitchen... very earthy looking... like we are cooking in a natural cave in the ground and used all lava rocks to build the kitchen....

[Boogie-D]

But for now, and until the rain stops this is my very humble beginnings...

[UtahBeehiver]

Since you can get vermiculite in the islands and you are planning on using it on the dome why not use it under the floor versa having CaSi sent from the mainland, at a 5 to 1 ratio you would need a min 4" thickness, 6" better. Vcrete is not as good as CaSi but it is an adequate option, just requires more thickness (rule of thumb, twice the thickness of CaSi)

[Boogie-D]

Aloha Russel... I wasn’t planning to actually use any vermiculite... I have been under the impression that in the Perlite vs Vermiculite battle Perlite wins in strength and water resistants (Hawaii)... however vermiculite is a better insulator?? Is that a correct assumption??..

@ david s after reading a lot of David s input I am seeing he prefers a mix of both perlite and vermiculite with a dash of clay... this makes a lot of sense as you get the benefits of both some strength/water resistance and insulation... and workability?? That’s assuming my assumptions are correct... Lolol.. insulating home brew? since David is the resident cast expert I am hoping he can set me straight as to what will be the best insulation home brew for me...

my hearth plan is to pour at least a 4 inch insulating home brew layer... followed by the 2” calcium Silicate board or it may have to be a ceramic fire board cost wise... I can get the CaSi board from PTI.. it’s a bit spendy but I think it will be worth it... my shipping cost out of LA are .45 cents a pound...

my dome plan is similar... 2 1/2 inches of the casting home brew... followed by 2 layers of 1 inch ceramic fiber blanket (2 inch total).. then I will cover that whole thing with 4 inches of the insulating home brew... with most likely chicken wire installed at 2 inches into the insulating home brew... please correct me or give me input if this doesn’t sound right...

at the moment still waiting for the rain to stop... it’s just enough to make it muddy and unable to burn the rubbish on site... so focusing on ordering my pilot dp super duty fires bricks... as well as getting my insulation material in order.... Thanks everyone for all your input feeling pretty good moving forward

[david s]

Perlite is a slightly better insulator than vermiculite when used dry on its own. However, as soon as you add cement to it to create either perlcrete or vermicrete the insulation value drops and there'll be no difference in the insulation value between the two. Perlite has annoying dust that is an irritant if you breathe in and cement seems to stick better to grains of vermiculite. Also the grade you use alters the uptake of water. Fine grade requires more water, which means more to eliminate, while coarse grade won't hold together quite as well. I pitch for the middle and use medium grade.

Refer to the table Russell posted to help explanation. Pumice is a free option for you if you're not too far from a beach as there are often pumice rafts depositing on beaches. You'd need to crush it a bit to get max grain size down to around 6mm.

[Boogie-D]

david s Is perlicrete stronger and more water resistant then vermicrete??? If they have the same insulation value then it makes sense to go with something that’s stronger and more water resistance..

please David can you elaborate on your insulating home brew mix..?? The mix you use of a split of both perlite and vermiculite... and a dash of clay?? You say it’s easier to work and obviously it has the values needed... and it binds together better?

I will not go look for pumice stone on the beach... we do have it but would be an effort to gather... we try not to ever take stuff from the beach.. David I live in a heavy AG area... there are several big AG distributors all around me... I use a lot of perlite on my farm and some vermiculite... I have a big bag out there now of perlite.. it’s very easy and cheap to get big bags of vermiculite too... there would not be any waste of either product as any left over would be used on the farm... in winter we use perlite for water drainage... in summer we use vermiculite for water storage...

in my farm experience vermiculite holds water and perlite expels water.... also in my farm experience perlite is a stronger substance... if we don’t want steam and water and rain (Hawaii) to absorb into the vermiculite then perlite seemed to be an obvious choice... if perlite alone is harder to work with and harder to get to bond together then I understand the benefit of using a half vermiculite mix half perlite mix and a dash of clay... wondering why your not recommending your insulating home brew to me? Thanks man.. my motto is do it right the first time...

[Boogie-D]

david s sorry David... I didn’t know you posted this in the materials air Crete thread... I’ll take this as you answer to my questions above sorry to be such a hound...

The insulating slab under the floor bricks requires a richer mix (5:1) for strength. I make batches of 5L vermiculite, 5 L perlite, 2 L cement powder and 3 L water. Because it contains a fair amount of cement you don't need the clay to make it stickier. For the brew over the dome, where strength is not an issue and you want good insulation, go leaner and use 10:1, in which case you need the clay to make the mix more workable.

The attached vermicrete insulating slab doc is useful as is the attached table of strength/insulating values for various vermicrete mixes.

Some holes cast into the supporting slab greatly assist the drying and draining of the vermicrete slab.Moisture under the cooking floor is the most difficult to eliminate.


Attached Files

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• Vermicrete insulating slab copy.pdf (20.8 KB, 0 views)

[Boogie-D]

Today stopped raining enough to burn the huge rubbish pile of halekoa trees behind the build site, as well as collect more lava rock, start laying out the cmu footers, and even made my scribe tool and marked out a piece of plywood with the layout... so in the end settling on a 33 1/2 inch radius... gives me an oven height of 16 3/4 inch ... it good to see the layout.. it should be just enough room for us... I snapped a few pics before dark... just need to adjust the rear footers deeper down.. then should be ready to form up the table.. a long way to go but making progress and Plastered mailed out the CalSil blocks...

[Boogie-D]

Aloha FB crew... a quick update on what’s happening... I am still awaiting materials in Hawaii... the CalSil blocks from plastered are still showing In transit from USPS arriving late from the 19th.. my buddy’s son, who runs the Los Angeles warehouse, decided to stay in Hawaii longer due to the LA Covid surge, till the 23rd now, and as of yet I have not got to meet with him 1 on 1 here on Oahu.. So still waiting to place my oven floor fire brick order and my roll of ceramic fiber blanket.. also after thinking it through going to install a ground slab under my cmu stand/walls... so need to do a lot of digging first to achieve that... we have had a lot of wet weather, and good surf that slowed me down as well as farm and health priorities... sometimes life on the farm takes over...

the progress has been to the farm and the large area directly behind the WFO and out door kitchen... I have 10 grafted fruit trees that need to go into the ground and these fruit trees will be planted in a line directly behind the WFO area... so I have cleared the land of rubbish shrub trees and burned it all... just need to dig the holes and get them in the ground soon..

the other progress as been the gathering of all the other materials... I have a line on and/or purchased the sand, lyme, clay, cement, perlite, and vermiculite...

the only thing I can think of is to improve my homebrew cast recipe...?? I see that some people are adding a ceramic fiber to there casting recipe? I have time to order something like this if it will be beneficial to me.. hope 2021 is going good.. aloha