42 inch WFO build in Utah

[natetanr]

I've been a lurker for a couple years admiring your builds and dreaming of a pizza oven. I had a bunch of CMU block left over from raised garden beds and decided to jump in and start building. I met with Russell and got a great deal on some ceramic blanket and checked out his fine work of art he calls a pizza oven. Wow pictures dont do that thing justice. Anyway I have lots of questions as I continue building. I have my pad poured, support wall up and reinforced structural hearth complete as well as cut my form for the interior arch. I think im going to do 6" of pcrete as I found 4 cu ft bags of perlite at J and J nursery for about $17 per bag.

A few questions that I'm trying to answer now at the moment. Many other questions to follow im sure.

1. Where do I get decent firebrick in utah?
I've called around to numerous places and most just resale interstate brick firebrick and up charge. Harbeson Walkier International sales there own brick but its quite a bit more expensive. Interstate brick sales there firebrick for about $2 a piece but .... they told me the brick size is 2.25" not 2.5" I spoke with someone from ksl that was offering used kiln brick (which would require grinding off mortar from each brick and was in kindof rough shape for $1.50 each) he was surprised I found fire brick for $2 a piece so he said he called interstate and they said there brick was rated at only 1000F? I plan on calling and confirming temp rating on the brick (seems very low) hopefully thats incorrect but the 2.25" brick height is a bummer, it would mean more bricks to build the oven then I planned for and adjusting my IT as I made it to be centered on at 2.5" brick height. Other places I see mentioned in Utah threads talk about interpace which is out of business and buehner block which is also out of business. Is there another place to find brick that Im not thinking of? Im frequenting KSL classifieds daily and am considering the used kiln brick that is a higher duty firebrick and sized normally but seems like it will take lots of work and time to grind off old mortar?

2. How deep of a "tunnel" or exterior arch do I build?
My hearth is quite deep and Im about to pour my pcrete. I centered the forms on my hearth but then second guessed it a I had lots of space behind and in front of the dome. I moved it back but then that felt like quite the reach. Do you guys like your oven to be closer to the front of the hearth or do you have a big landing or long tunnel? The long tunnel seems bad as it might make it more difficult to work things in the oven.

3. CalSil or stick with pcrete?
I'm planning to use 6" of pcrete to insulate the hearth and have it formed up. Will I wish I spent more money on calSil? What are drawbacks of pcrete besides height required to insulate similar to CalSil. EJ Bartells tells me they dont have calsil board but could get me a 1.5" by 12" by 36" tile and Its works out to about $6 dollars a sq ft and I would need to buy at least 36 sq ft for them to ship it to there Utah office. Its a weekend and I really want to work on this so will likely go with 6" pcrete.

[UtahBeehiver]

I am glad, with a little prodding, that Nate has posted pics of his build. It was nice to meet him in person. I understand his urgency on getting his build going. I was up at the ski resort yesterday and there was about 9-10 inches on snow already. IMHO, having a landing out front vs a deep vent chamber is better. I help to have a staging area for tools, food, BEER, etc. In your search for fire brick, if possible try to avoid Super Duty bricks (which I used, not because they are any less effective, they are really hard to cut and you will go through a lot of diamond blades). That said at the right price vs blade usage cost may even out. I know builders only having to use a blade or two on medium and low duty bricks.

[natetanr]

I ended up driving out to Heriman and picking up the used kiln bricks. My guess is they are super duty hard bricks. The seller had demoed 3 or 4 kilns with plans to make the stuff into his own kiln. Unfortunately most of the brick had been picked through and sold by the time I arrived and another builder was there purchasing brick who was also making a pompei oven and the seller ended up not having enough of the standard brick sizes. I had to make due with some odds and ends like wedges and larger square bricks to have enough for the the floor. The floor will have to have 3" height bricks. Its gonna be tricky putting the floor together with all the wierd sizes but I think I can make it work.

Lots of grinding of old mortar to do but picked up a diamond cup grinder and it goes pretty quick but is dusty. The seller also had a bunch of busted up insulating fire bricks he was getting rid of. I had started my pcrete with some stuff I had on hand but ran out of cement and only had a 2 inch layer or so. I ended up puting the insulated fire brick in a pcrete sandwich as I heard insulated firebricks work well for the insulated hearth. Ended the day by finishing up my insulated layer and cleaning up some of the brick. Still need to pickup some fireclay and lime and borrow or buy a 10" saw.

Anxious to start laying brick before the snowfalls.

[david s]

Brick dust is quite dangerous to inhale. Rig up a water mister and wear a decent respirator.

[natetanr]

Thanks for the advice David. I used an el cheapo dust mask but probably should upgrade to a reusable respirator. Attached some more pics showing the pcrete sanwich and testing out layouts for the floor brick.

[UtahBeehiver]

FYI,

K value of insulating fire brick is about 1.0 (imperial) and 5 to 1 vcrete is about 0.72 -0.75 so fairly close to each other, good use of repurposing materials. The vcrete contains a lot of water so you really need to let it dry out well before placing the brick floor on, yes it is raining today so cover it up.

[natetanr]

FYI - Drove out to ogden interstate brick to pickup fireclay. They told me it was fireclay but after loading it up and paying more then I should have for fireclay I looked at the ingredients and realized this was a refractory mortar that you just add water called firerock refractory mortar. Its $25 for a 25 lb bag. I called the Salt Lake interstate brick and they told me they cary fireclay and I made sure it was just clay powder and not any premixed mortar. So lessen learned, if you need fireclay you wont find it at the Ogden interstate brick only the SLC interstate brick caries the fireclay. I assume you could also pick it up from capital ceramics. Also borrowed an old 10" HF tile saw but found I forgot to get the tub that holds the water and some of the water hose parts were missing so no progress for me other then flipping floor bricks over and trying to figure out how to reduce the chips and gaps. I plan on making chipster's jig to cut the brick bevels and tried working on that last night but couldn't scrounge up a spare hinge.

On the floor how thick of a layer of sand/fireclay do you need to bed the floor brick in and what kind of ratio do you use? Can you use just sand? Will the fireclay/sand mix bond to the floor brick? I've got some floor bricks that are kind of warped or misshapen so Im hopping I can do a bed that will allow me to push some of the bricks down more then others to even out the floor.

A decent respirator should arrive today and hopefully I will have ingredients for homebrew and parts for the tile saw. Anxious to get moving on the brick cutting and laying.

[UtahBeehiver]

I used a 3/8" notched trowel for the fire/sand bed. The clay helps bind the sand, it is wet mix not a dry mix. Attached is a pic of what the fire clay from Interstate should look like. Again, let the vcrete dry out, once you lay the floor down, it will be much more difficult to get the water out. Be patient. On the wet saw, since the water tubing is missing, go to the big box store and buy a length so the pump can sit in a 5 gallon homer bucket for the water source and not in the tray, this way sediment will not mess the pump up.

[natetanr]

Yep I got some HC Mudox fireclay this morning, the sales rep tried talking me out of it saying the firerock mortar was 10 times better and that the homebrew stuff would fail and I would regret it. I dont hear anyone on the forum complaining and I didnt want to pay $25 per small bag so I ignored the sales person and went with plain old fireclay. Russel I see you used quartz for your homebrew? I read something about using coarser grit sand as you get bigger mortar joints. Did you stick with the fine quarts for your whole build?

Yeah I plan on using a 5 gallon bucket for the water pump. Also picked up some firebrick while I was out there at interstate for good measure. There firebrick is soft and easy to damage just loading it in the truck several corners got chipped off.

[UtahBeehiver]

I used the quartz the whole build, although smaller than masonry sand, it is sharp edge. Don't use playground sand, too small a grain and smooth. Home brew has been used on hundreds of builds on this site. Make sure the bricks are not insulated fire bricks (IFBs), ie light in weight and can be cut or scored easily with a hand saw. IFBs are NOT what you need for your oven. I wnet through more than one 50 lbs bag of fire clay. I dry premixed the homebrew in a 5 gallon homer bucket with lid then only mixed small batches in a small gallon bucket. Any extra or if it started to flash went on the outside of previously layed dome bricks,.

[natetanr]

Got most of the floor trimmed. Had to crawl with the brick cutting. I ended up with some very hard bricks. How do I know the pcrete is dry enough to lay the floor? Also I’m debating a full soldier or a half soldier for my first course. Is it better to do a half brick for the soldier? Also I’m worried about having enough brick so I have the new light duty firebrick that I’m trying to decide where to incorporate? Maybe the outer entry? Would it be bad to mix light duty brick for the soldier then use the harder heavy duty brick for subsequent courses?

[natetanr]

[UtahBeehiver]

I personally would not do a full soldier, the outward pressure at the top of the soldier and dome may require that you buttress the soldiers. I would do a half header or if set on a soldier course, a half height soldier. See attached pic.

[natetanr]

Ah that brick terminology guide is helpful. I never understood sailor versus soldier. I would do a half header but my floor brick is 3" thick where the rest of my brick is 2.5" thick so I would be half inch below the floor with a half header. Any opinions on mixing the hard used brick with the soft new brick. I think I will try to save the soft low duty brick for my outer entry.

[UtahBeehiver]

Actually that is okay and even better for the first course, then the second course seam extends below the surface of the floor.eliminating the chance of the peel sliding into the joint between the dome and the floor. Ideally it would be best to keep like bricks in one area rather than intermix, ie floor area, vent area, dome area. High duty bricks typically > 55% Alumina do not expand that same a low duty bricks so intermixing could cause some potential stresses. At our cooking temps does it matter, don't know.