No announcement yet.

Mongo's 42" CT Build

  • Filter
  • Time
  • Show
Clear All
new posts

  • mongota
    Re: Mongo's 42" CT Build

    Chris, thanks.

    Russell, I appreciate the feedback. Multi-day cooking is indeed a goal.

    My elbow height is 45-1/2", I can get that with the 44" height as drawn plus I can get an additional inch or so by having the walking surface in front of the oven being lower than the oven's base slab.

    The info on the compressive strength of the insulboards will help in my research.

    Thanks, Mongo

    Leave a comment:

  • UtahBeehiver
    Re: Mongo's 42" CT Build

    Quite a post. But you appear to be thinking it out. IMHO here are my answers to you questions:

    I have 42" igloo.

    1. You can never over insulate but you can under insulate. I have a total of 3.5" of floor insulation. 2" of FoamGlas and 1.5" of ThermoGold 12 Ca Si Board. 4" would not be too extreme especially if you want multiday cooking.
    2. Elbow height is a good rule of thumb, you do not want to have to stoop over to load and unload your oven.
    3. Same as #1, I have 3" ceramic fiber blanket with 3" of Vcrete. You will have to spend some time fitting the CF blankets to your dome shape since you are not installing v or p crete. Using this helps take the irregular shape out of the blanket. You will only have 1" of stucco avail. for shaping.
    4. I used Thermgold 12 which has a compressive strength of .69Kpa, Insblok19 has .3Kpa, and FBs board has .5Kpa. I am sure there are others out there too but I choose one with a higher compressive strength.

    Good luck

    Leave a comment:

  • mongota
    Re: Mongo's 42" CT Build

    It's October and I'm juggling a few other projects. All I really hope to do this year is to get the base structure done. Footings to frost (42" here in CT), 12" wide CMU walls below grade to get to grade, then a slab-on-grade to cover the below-grade work. On top of that slab will go the hearth walls, then a slab to cap the hearth. The mortared stone walls are what will slow me down.

    The following spring I'll do the dome.

    Now for the oven plans...I drew these up over the past couple of days. I've used my eraser quite a bit, so there's a chance that dimensions in one drawing may not follow through perfectly to the next. It'll all be ironed out in the end. Or cast in concrete?

    Here's a rough view of the front of the oven:

    The slab-on-grade will be 76" square, with the top edge chamfered. The flat surface of the slab will be roughly 74" square. The corner posts will be set in 1" from the edge. The base structure will be roughly 72" square.

    The base will have 10" square cast concrete "corner posts". The front and back of the base will each have a 24" wide door, the doors will be surrounded by a cast concrete arch. Wood will be loaded through the "back door" and taken out of the "front door". That'll prevent me from having to drag wood through a couple of gardens and a couple of gates to load the base with wood.

    The walls will be CMU construction covered with a roughly 6" thick veneer of stone. I live in CT. I have no shortage of stone. lol

    The slab that the WFO will be built upon will be roughly 80" square and is right now pegged at being 5-1/2" thick, it'll overhang the walls below by about 4". I'd like the slab to have a bullnose edge, probably a covered bullnose.

    The oven will be an igloo design, right now I'm planning on covering the igloo with a veneer of stone bout 3" to 4" thick. More on that later. Because I won't have a doghouse full of perlite/vermiculite, I have this drawn with 4" of insulation around the dome oven.

    With 4" of board insulation under the oven floor brick, that gives me a cooking height of 44" above grade. I'm 6'4" tall.

    Question #1: Is 4" of board insulation overkill?

    Question #2: Is a 44" cooking surface too high?

    I can maintain the 4" of insulation and lower the cooking surface a bit. Or I can reduce the 4" and reduce the height of the cooking surface. Either/or, or leave it as is.

    More foundation detail, this shows the wall structure that makes up the base:

    The above should show the 10" square corner posts that are "notched" to receive the corners of the CMU wall. The notching reduces the volume of concrete needed to cast each post to exactly three 80-lb bags. Nothing is perfect in the world of concrete, but I'll take it where I can get it, even if it's just in the design phase.

    Combining the thickness of the roughly 6" mortared stone veneer and the 8" CMU wall, the foundation walls will be about 14" thick. That load will be carried through to the footings below grade. Overkill in so many ways. But my igloo will be heavy as planned.

    Next, the drawing below shows two separate things combined on one sheet of paper; on the left is a simple detail that shows the CMU wall meeting the corner post. The right side shows the rough scale and detail of the cast concrete corner posts.

    And finally, a cutaway of the oven dome structure and how it will sit on the slab:

    The dome has a 42" interior diameter. Dome bricks are 4-1/2" thick. Bricks are covered with four 1" layers of blanket insulation. Blanket insulation is covered with a ~1" thick rendering of lath and stucco/mortar. That may end up thicker. We'll see. That 1" thick render layer is covered by a stone veneer roughly 3" to 4" thick.

    Question #3: Is four one-inch layers of blanket insulation too much? Diminishing returns? Again, I'll have no vermiculite/perlite. So this will be it.

    The drawing shows the edges of the igloo veneer to be a couple of inches away from the edge of the lab. Realize that the slab in the above drawing is actually the 74" square slab-on-grade that the hearth is built upon. The 5-1/2" thick cap slab that the igloo will sit on will is 4" wider in each dimension than what is shown in the drawing. So if built as drawn, the igloo veneer will actually be about 6" from the edge of the slab. I hope that makes sense.

    The oven vent size and landing size are guesses at this point. They can be tweaked as needed.

    At the bottom of the drawing, what was drawn is a cutaway view of a cast concrete arch that will cover the raw edge of the firebrick arch and stone veneer.

    Question #4: Is one type of board insulation stronger than another regarding compressive strength?

    I'll have a roof over head. Might be built as a part of the oven. It might be built as an extension of my pergola roof. Either way, the chimney will be properly detailed.

    A long post, I know, Probably repetitive, I know. Time to get my wheelbarrow, my pickaxe and my shovel.

    Any comments are welcome.

    Best to all, Mongo
    Last edited by mongota; 08-03-2018, 07:46 PM.

    Leave a comment:

  • hodgey1
    Re: Mongo's 42" CT Build

    Nice space, love the pool and patio. Best of luck with your build.

    Leave a comment:

  • mongota
    started a topic Mongo's 42" CT Build

    Mongo's 42" CT Build

    I figure if I start a build thread, then it'll make it real. Or force me in to action. lol

    Planning a 42" build out by my pool. The pool setting is fairly subdued with regards to the color palette. Natural setting, neutral colors. Some stone, weathered cedar fencing, weathered wood pergola, etc. The entire pool area is DIY with the exception of the pool shell.

    In the following photo, the currently mulched area between the slate patio and the stone retaining wall is where my "cooking area" will go. The mulch will eventually be a hard surface. I'll remove the sloped section of fence on the left and the oven footprint will straddle the fence line, with 4' outside of the fence (to the left) and 2' of it inside of the fence, with the oven opening facing to the right.

    If you can make out a "campfire area" recessed into that retaining wall, that'll be replaced with a roughly 6'-8' long raised firebrick hearth, to accommodate a rotisserie for pig roasts, etc. That hearth will still be able to serve as a campfire area. The area to the right, where the edge of the patio is curved, will be where my grill will go.

    Overall the cooking area will have a "U" shape; the wood oven on the left, the 6-8' long raised firebrick hearth in the center, and the grill to the right.

    I got nixed when trying to post this for having six linked images, so I'll start the thread with this "generic pool area" post and include the oven design in the next post.

    Cut and paste had better