SC Chris's 42" WFO build

[SCChris]

Re: SC Chris's 42" WFO build

Question on the IB. I'm figuring on mixing some thin set to attach the IB to the base. I’m guessing that this is what others have done but haven’t really found any mentioning of this. If I didn't live in earthquake country I might just assume that the weight and surrounding structure would hold things together.

Chris

[SCChris]

Re: SC Chris's 42" WFO build

Thanks Dino and Papa.. I'll give the shoulder cuts a try and see how it goes.. If I cut a few and throw in the towel on cutting the rest of the shoulders on the soldier course, it'll be with first hand knowledge. I'll know a bunch more by Sunday afternoon.

Chris

[papavino]

Re: SC Chris's 42" WFO build

I didn't cut the sides of my soldier course for my 36" oven. There was an awful lot of mortar used to fill the gaps. If that's a concern for you, then I'd go ahead and try it, but like Dino said, I was more interested in going vertical than minimizing the pie shape for my soldier course.

[Dino_Pizza]

Re: SC Chris's 42" WFO build

Hi Chris, I know you'll be happy with the 2" of Insulating Board. And your oven height will be just right too.

RE Soldier Course Tapering:
As you saw on my threads drawing this morning, I did NOT taper my soldiers wide side. On a 42" WFO it leaves a 9/16" gap at the outside that gets smaller across the 4.5" brick face until they touch. I think this is quite tolerable of a gap. I WAS a bit shocked though by how much of my $$$ Refmix went to fill those gaps. A smaller oven diameter would have increased the gap and I would recommend tapering. However I think this gap for a 42" is fine. And, if you did taper, that's about 40 bricks and a lot of cutting and flipping and cutting on your tile saw at a time that I'm sure you'd rather be placing your first oven ring and tackling the bigger question of "V" gaps and compound tapers!

After my 1st few ring courses that came out surprisingly tight with little mortar, I had wished I'd tapered the soldiers too, but after doing my arches, vent and the slooowwww race to the dome keystone/plug, I'm glad I didn't spend that time. BUT, that's just me. The pics of others tapered soldiers is beautiful and I envy them. So, good luck, hope this helps, -Dino

[SCChris]

Re: SC Chris's 42" WFO build

I've ordered my insulating board from Foundry Supply in Santa Fe Springs. The bad news is that it's not cheap. The good news is that I'm comfortable that it'll better insulate than would Vermiculite Concrete and because of this I should use less wood. Additionally, since I didn't get the V.C. done when I did the structure slab, It'll save time on the build. My other plus is that the slab height stands at 38". When I add 2 for IB and 2.5 for the firebrick floor I'm at 42.5 for the oven floor rather than 44.5 inches. Some have indicated 5" of VC and this would have put me close to 46" as a floor height. I wasn't comfortable getting this high.

Now that the decision to use IB has been made, my next decision is to cut the sides of the soldier course or not. I'm cutting the top of the soldier course, it makes structural sense to me to do these cuts. I want to minimize the occurance of pie shaped grout lines as well as doing my best to stagger the joints. But I see many who don't bother to bevel the sides of the soldiers to minimize grout. I'm leaning toward making these cuts even though brick saw blades don't grow on trees.

Chris

[SCChris]

Re: SC Chris's 42" WFO build

Here is a photo of the oven in progress.

Chris

[SCChris]

Re: SC Chris's 42" WFO build

I'd like to keep the slab as cool as possible understanding that the heat will push into the slab. Warm is ok hot isn't and I guess if the bottom of the slab remains comfortably touchable, hours after a running to Pizza temps on the inside I'm ok with that. Is the insblock14 more like a soft insulating firebrick, "SIFB"? I can get these all day long, not cheap but about the same as IB. I have wondered how IB and SIFB compair as insulators.

Chris

[dmun]

Re: SC Chris's 42" WFO build

I used two-and-a-half inch insblock14 under my brick floor. I plunked the boards down into the wet concrete after I poured the slab, and tapped them into the wet concrete. I understand this trick won't work with cal-sil boards, as they are very absorbent of water. My brick floor went directly on top of the boards. My support slab remains cool on the bottom at full pizza heat, although it's warmed up a bit by the next morning. (that heat has to go somewhere)

[dbhansen]

Re: SC Chris's 42" WFO build

Yes, directly on the 4" concrete slab.

Daren

[SCChris]

Re: SC Chris's 42" WFO build

DBHansen, So you went with IB directly on your slab, correct?

Thanks

Chris

[dbhansen]

Re: SC Chris's 42" WFO build

I'm happy with 2" of IB, but I suppose it all depends on how much heat loss you can accept. The roof of my wood storage area is warm to the touch the morning after pizza, but I can still bake Sunday's dinner after a Friday fire, and I haven't fully insulated the dome yet. I considered 3-4" of IB, but it would have raised the oven floor too high for my liking.

[SCChris]

Re: SC Chris's 42" WFO build

The last thing I want to do is to under insulate. I'd rather have too much and use less wood and have the oven stay hot longer.

Chris

[wlively]

Re: SC Chris's 42" WFO build

IMHO with 2" of IB or FB board you will not need the vermiculite concrete. I have 1" sitting on top of 3 inches of vermcrete. If I were to do again I would not bother with the vermcrete and use the board alone.

Also remember that insulation is very important and is money well spent. You almost never have enough of either.

[SCChris]

Re: SC Chris's 42" WFO build

7/20/09 - My hearth was poured yesterday. I had a pallet of Quikrete delivered by Lowes earlier in the week and figured I might need as much as 30 90# bags. The block and rebar were in place but because of the amount of concrete that needed to be mixed and bags to be moved to the mixing site I needed help. Dan came by at 8am and by noon we had the pour finished. I had hoped we could get it done by noon. The oven site starts to get full sun at about 12:30 and with the hot weather right now, sun and concrete work are not what I consider a great match. About 3 in the afternoon I was comfortable with getting the slab covered with burlap and wetting things down. With the weather so hot and the slab getting full sun in the afternoon I really want to keep things wet for the next few days.
The oven structure presented a few challenges that I could have avoided had I been able to focus on the oven project when the concrete contractor was pouring the patio slab, but it?ll all work out just fine in the end. The biggest challenge was avoiding a finished oven floor height that going to be workable while still gaining some value from the space under the hearth slab. I integrated a lintel into the hearth slab by using several lengths of 5/8 rebar over the structure openings and going 1/2 rebar on an 8? grid. Every core in the block structure was filled with every other core with rebar to the foundation, and rebar at the openings. Steel and Concrete are cheap the labor involved isn?t, so I over built.
I?m now at the stage where I need to choose Vermiculite and concrete, ?VC?, or insulating board, ?IB?. It sounds like 4 inches of the vermiculite mixture will still allow a great deal of heat to escape through the floor. I see some recommending at least 5? to minimize the heat loss. I think I?ve seen some recommending 2? of the VC in conjunction with 2? IB. I think I see that Dino used the 2? board alone. Does anyone have some feel for R-Value of IB compared to VC. Can I do better with 2? of IB then 4? of VC?

Thanks

Chris

[SCChris]

Re: SC Chris's 42" WFO build

When I spoke to one of the sales people last week he indicated that he'd had 2 people come by for materials the previous week. I know how projects take many trips to the building supply, but it sounds like I have more than a few neighbors who have built who are building and will be soon. I can't help but think that if SL carried Refmix or HS50 and the Fiber board and blanket it wouldn't have time to get stale.

Chris