Boogie’s cast 37inch WFO Hawaii

[Boogie-D]

aloha, my name is Boogie-D and I am going to build my first wood fired pizza oven and adjacent out door kitchen on Oahu , Hawaii... I live in a off grid farm house with my wife... We grow tomato, basil, oregano, thyme, pepper, rosemary, egg plant, taro and squash we also raise our own chickens... my wife and I often have dinner parties of 10 guest.. we don’t have an oven and we miss pizza, bread, cookies, pies, roasts, and any thing to do with oven cooking... so it’s time to start my project and get back to cooking things we love to eat... off grid style wood fired oven and kitchen.

step1) It all starts with the base... I have chose to build a concrete table to support my pizza oven... I will use 4 cmu cinder block table legs to support a 3 inch concrete table... ’ll make my footings and poor in place the cmu legs and table top... I’ll use rebar in the 4 cmu legs and bend them into the table center as well has place hog wire through the table top... I was super lucky to score a whole bunch of lava rock Vaneer for free to cover up my cmu legs... lava rock will be a nice natural finish to all my cmu in my out door pizza oven and kitchen...

step 2) the oven floor... this is a very important step... I have chose to use 2 inch insulating ceramic fire board, followed my a 4 inch perlicrete insulating coat.... and then thin coat of fire mortar to set my oven bricks... oven fire bricks rated for food contact are hard to find in Hawaii and may be my biggest obstacle.... The fire bricks that Tile Co Inc carry are fire bricks used for dome construction not food contact but they do carry 50 lb bags of fire clay... I have been calling Pacific Refractories Honolulu but no answer or call backs yet... from previous Hawaii builds here on FB Pacific Refractories has Mizzou hi temp castable cement... as well as fire brick... and insulating fire blankets... but since I can’t get in touch I don’t know if there bricks are for food contact... food contact bricks might be the hardest thing for me to get to Hawaii.. I understand that I should form my perlicrete insulating coat and cut my fire brick so that my cast dome fits over the oven floor for better insulation...

step 3) casting the oven / dome/ and tunnel... for this I chose a 37 inch diameter or 95 cm. circumference .. I felt this was the appropriate size for my wife and I, as well as our 10-12 people farm dinner parties... I have order a yoga ball 95 cm and it arrives today.... on a 3/4 inch sheet of ply wood 4x5ft I will form the ball... I’ll cut out the diameter on the form as well as mark a 2 1/2 inch guide line for the castable.... I am thinking to construct a form around the castable line around the ball and tunnel to make it easier to pour the home brew and go... It would be nice if my form/mold would be reusable so I will try to construct that way.. it sounds like my best option for casting in Hawaii is the FB home brew recipe found here 3:1:1:1 sand cement clay and lime... when I form my tunnel I will form in a vent box above the arch and that will just touch the ball to allow smoke to rise up from the dome into the vent box and out of the chimney... no smoke out the door.. I have a grand design for the chimney as I want it to be a highlight feature that will be artistically decorated... more on the chimney later..

step 4) insulating... after the cast home brew oven has set I will place the dome over my floor fire bricks and insulating perlicrete coat... then I will cover the entire oven with ceramic fire blanket... then I will cover the insulated dome with a 3-4 inch layer of insulating perlicrete with some chicken wire for reinforcement.... after that I will cover the entire exterior with a thin stucco and attach lava rocks over the entire surface of the oven... we have lots of lava rock in Hawaii and we want the oven to looks like it’s a cave we are cooking in.. with a cute little brick arch entry and a super decorative chimney with a mermaid and dolphins... Lolol ..

step 5) customize.... I am thinking to form in a pipe to the right side of the pizza oven wall that will attach to my wood fired 4 Burner range top stove, the range top stove doubles as an exterior burn box that can be be used to deliver cold smoke to the oven and for cold smoke cooking.. of corse I would have to form and pour some kind of plug for that and when using the oven.... was also thinking to form in a gas pipe... saw a build were a guy plumbed in a propane gas burner... I can imagine nights I don’t want to build a fire and this might be a nice added bonus to the wood fire oven??? Convenient cooking all the time??

I’ll guess I’ll stop here... nothing is set in stone... the reason I am posting this is to get your advice before I begin.. am I on the right track? Do I need to change anything? Right size for my needs? I have heard David s and others prefer a sand mold versus the yoga ball mold... ? any thing you can share from your experiences? I really want to do it right the first time!!! Thank you very much!!! Aloha

[UtahBeehiver]

Step 2, the ceramic board (aka CaSi) should be under the firebrick and the pcrete between the CaSi and the concrete table. The CaSi is the most thermally efficient insulation. Attached is ratios of p or vcrete and where they go.

[Boogie-D]

Hey thanks Russell.... was just looking through your photos (sweet)... so its concrete table, perlicrete, then the ceramic board then the fire brick for the oven floor.???.. mahalo... maybe you can help me decipher the table graph you sent me and suggest the best ratios for my floor and dome.... also for the perlicrete insulating floor my diameter is 37inches... on a 48 inch table.... would it be acceptable to just pour the perlicrete across my whole 4x5,table... that seams easier then making an exact form of the floor?? Or does this create the dreaded heat sink... appreciate it... did you make a you tube video of your wfo build? thought I saw one very similar to those pictures... and your family in Maui? Do you get to spend any time in the islands? I bought a bunch of cmu and cement yesterday from home depo... getting ready to start step 1

[Boogie-D]

I’ve been really looking closely at your build pictures Russell, in particular the floor pics and the one with the arrows... you use a foam glass layer... then the CaSi layer... what I like is the way you made that jig and the ease of cutting that foam glass and the CaSi... this seams a lot easier then making a form and pouring the perlicrete... hmmm... a lot to think about...

by the way you oven is really incredible.... mahalo

[UtahBeehiver]

correct on layers. Floor ratio by volume is 5 part perlite or vermiculite to 1 part cement, dome insulation 8 to 10 to one. You can lay down floor insulation full floor or circular but note CaSi is very soft and not very abrasive resistant so I would cut to meet the "OD" of the oven. We insulation is one of the most common problems of poor oven performance.. The key is to make sure all parts of the dome and floor have insulation under them so the concrete hearth does not become a heat sink. I usually get to Oahu or Maui every couple years for family reunions but not this year due to the pandemic.

[NCMan]

Hello Boogie-D and welcome!! Sounds like an interesting project you have underway there. Keep us all posted w/your progress. Best of luck to you, also.

[UtahBeehiver]

There have been a ton on innovations since I built my oven in 2012. FoamGlas is very difficult to obtain but it is nonhydrophobic (won't absorb water) so great to protect CaSi from water on hearth. There are some new CaSi and Perlite hard boards that are water resistant and have good thermal conductivity (k value) and compressive strength. Again it may be hard for you to obtain in the islands, they are not big box store items. where as perlite or vemiculite may be more readily available, k values are not as good so need more thickness but a decent insulation option.

[Boogie-D]

Mahalo Russel and NC man... I like it, believe you can and your half way there... that’s my motto... hey Russell I tried to shoot you a pm and give you my phone # but didn’t go through...

I think I have something wrong,,,, I was planning to have my dome surround the floor.... but it looks as if I want it to sit on top of the floor... got it....

I am leaning toward just perlicrete my whole concrete table... then cut the CaSi to oven size... but also like the look of the foam glass and cutting that to fit... Russell would you happen to have links on the best place to purchase the CaSi and Foam Glas.. or maybe this info is in the materials section? Would like to calculate the cost of shipping foam gas to Hawaii.... pretty sure I will have to ship in the CaSi as well as my oven floor bricks... no way around that..

thanks again for setting me straight

[UtahBeehiver]

You can have the dome sit around the floor or on top does not matter as long as neither the floor or the dome sit directly on the concrete table, in other words insulation under both. It is easier to set the dome on bricks rather then cut the floor to sit inside, lots of tedious tangent cuts. Distribution International is a place you can check out, they have offices all over the mainland (the Forum, does not allow direct commercial links so just Google name). I would check for any local "refractory suppliers" on Oahu first. Like I said, Foamglas is a great product but difficult to procur.

[Boogie-D]

Mahalo... I guess I am jumping the gun a bit.. getting excited... I probably should focus on one step at at time beginning with my base.... I think I should state that the farm and house that I am building my wfo on is not my land I just lease it... so hence I am trying to be as cheap as possible and hopefully with the option to at least be able to take my cast dome and floor bricks with me when I move (highly unlikely?)... I don’t want to cut corners but need to be thrifty on cost.. especially on the base/ table as in all likelihood that will remain... focus focus...

step 1) questions... for my base... in an effort to cut down the cost of what I leave behind... I have chose to just make a 4 corner base out of cmu.. I see a lot of builds with base walls in a u shape with 3 complete walls... I just want to have 4 columns in each corner out of cmu that will kind of act like a sonotube form... so basically my concrete table will be set on 4 legs of cmu... my question is will this be a strong enough solution? And is a 3 1/2 thick concrete table adequate.? Thanks again for the advice...

[Boogie-D]

After searching the forum for 4 corners stand I see that neil2 and kebwi both have the type of stand I am trying to design... just 4 legs... no bottom foundation... my entire house sits on piers so I know this can be done... on footings of course... kebwi used 2 cinder blocks to build each of the 4 corners up... where as Neil2 used 4 sonotubes... I’ll keep searching the forum for this type of 4 corner stand...

[Boogie-D]

[Boogie-D]

[Boogie-D]

Looks like Neil2 got away with 3 sono tubes

[david s]

By cantilevering the slab over the piers the span between them can be reduced as well as the supporting slab thickness. Using this method also places the weight of the oven directly over the piers.