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Longmont, CO new WFO build - casted over sand

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  • cnegrelli
    replied
    Thanks for the feedback of Vermicrete and Stucco. I'm going to make sure I have some wiggle-room of a few inches either way, as I may change my mind on the final finish (Stucco igloo vs. enclosure).

    I'm doing a 2" inner dome, but also still was considering a little thicker for extra mass. But I think I will go with 2".

    My insulation is the FireMaster FastWrap+, which is 1.5" thick. I will do 2 layers minimum, but would like feedback of doing a third.

    My use model:
    Mainly Pizza - heat up time, fuel usage minimized. Based on experience, I will make them one at a time. So a huge oven is not necessary.
    However, I am trying to balance that to allow for some cooking roasts and bread. So I'd like the size to accommodate this use model.
    I currently believe a 32" Internal Diameter (ID) is sufficient. Comments?


    My other assumption is that while the 2" casted dome (with firebrick floor) will not provide maximum thermal mass, if I can super-insulate it, I should have good results in retaining heat for bread, etc.
    I plan on a thermal break right where the dome meets the gallery (inner arch). I will build a very good thermally resistive door. I have the blanket to go 4.5" thick, plus vermicrete. I plan on 2" of FoamGlas under 2" of CaSi board under the oven floor.

    Comments and discussion requested!


    Leave a comment:


  • david s
    replied
    You will need to decide how thick you want to make the inner dome first. Most cast ovens are 2" thick. The Primevera 60 is 1.5" thick. You then need to decide how much thickness of blanket you want. Two layers of 1" blanket and a 1.5" layer of10:1 vermicrete is about normal, then the thickness of the outer shell. I do mine around 12 mm which is probably about the min. Add up all your numbers to get the outside diameter.

    Leave a comment:


  • cnegrelli
    replied
    I know I've seen discussion here on this top, but for planning purposes, assuming my igloo has 3" of insulation and a minimal amount of Perlcrete/Vermicrete to smooth that out and reshape, and then Stucco (with some water resistance additive in final coat), how much thickness should I plan for from the insulation layer out?

    Leave a comment:


  • david s
    replied
    Yes, that'll be good. The stuff sets fast, particularly in hot weather so don't mix up too much in one go. I use chilled water in hot weather which gives you extended working time.

    Leave a comment:


  • cnegrelli
    replied
    I've been searching for the best castable source and I finally found one that is both stocked locally and at a more reasonable price. Would this be the right stuff here?

    The "foundry guy" suggested this product for troweling on over a sand mold and for casting a flue. It's 145 lb/cu.ft. density.
    Contents is:
    Al2O3 45.0% SiO2 48.0% Fe2O3 <1.0%

    http://www.pryorgiggey.com/TDS/Castm...28%20HR-td.pdf

    Leave a comment:


  • david s
    replied
    I just do the corners.

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  • cnegrelli
    replied
    I can do that! Every block or just 4 corners or so?

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  • david s
    replied
    It sounds plenty strong enough. I usually pin the stand to the foundation slab. You can do this by drilling into it and hammering in a short length of bar.

    Leave a comment:


  • cnegrelli
    replied
    Bumping - anyone care to join in and comment on the existing pad reuse? Please?

    Leave a comment:


  • cnegrelli
    started a topic Longmont, CO new WFO build - casted over sand

    Longmont, CO new WFO build - casted over sand

    After 4.5 years of lurking, I'm now about to build the WFO. I've worked out most of the materials and found pretty much everything I need. Some useful info on where to get materials came from DrakeRemoray and Coloradoredusa. In the end, Russel's advise of EJ Bartells (now Distribution International) for insulation products and Threewit (firebrick, castable, etc), along with our host site, have been the best sources.

    I will post plans soon, have been accumulating a lot of knowledge, especially from david s UtahBeehiver Gulf and others. My basic plan is to build a standard stand. I plan to cast a dome that will be a 28-32" I.D, over sand mold. Insulating base layer of 2" of FoamGlas and 2" of CaSi board (as seen UtahBeehiver), to alleviate moisture concern.

    Firebrick floor (cheapest source found is $1.95 USD per brick, after much searching. Gave up on pursuit of used, as they were all in questionable condition and heritage.
    Casted dome over sand mold using a commercial castable (likely Heatcast 40 - again not cheap here). With SS needles if I can find them. Will also cast an entry/flue area. Thermal break likely between inner arch and casted entry.

    Insulated with Ceramic blanket. 48" high 6" Inner Diameter duravent chimney. Plan is to stick with a stucco igloo design, uncovered. I plan to vent the shell with david s chimney vent designs.

    Before I begin, I have the first question for the board. I am hoping to re-use the concrete pad that held a 4000 lb hot tub for 10+ years. It's reinforced concrete that is 4" deep. It held the hot tub for 10+ years (fully loaded) and this past winter without a load, with no heaving or cracking. I plan to dry stack cinder block, filling every other hole or so with concrete and rebar. No plan to tie the rebar into the pad.

    Any concerns with this pad?
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