Texman Build

[Mike D]

Re: Texman Build

-I did mine in a wheelbarrow. Mix the vermiculite withe the portland cement dry first, then mix in the water until it looks like oatmeal. It takes more water than you think. If you mix it too dry it won't hold together very well. Keep the forms on for a wile or as long as you can (there is no reason to take them off for a little wile anyway).

-I did the vermiculite mix under a layer of the FB board (just for extra insulation).

Mike

[DTHERR]

Re: Texman Build

I mixed mine in a old tub that was going to the scrap yard (knew it would come in handy one day) .. mix it by hand wear a elbow lenght glove and just fold it all together add water as needed

[Lburou]

Re: Texman Build

Tracy

I saw a couple good videos on youtube about mixing vermicrete, but did not go that route myself. Wheelbarrow mixing is often described here. Where you end the vermicrete is up to you.

[texman]

Re: Texman Build

I need some vermicrete advice, please. I have read the various posts regarding using the vcrete, seems fairly straight forward. Except, how do you mix this stuff? Wheelbarrow, bucket, in the form, etc? and should i use a mixing attachment in a drill like you would for thinset or sheetrock mud. I am thinking using a drill to mix will add air and may break down the vermiculite, which i think is not good. mixing in wheelbarrow seems to be the best and then transfer to slab with shovel?
I am thinking of using a 4:1 mix or 5:1 and maybe some sand to make a stronger mix. i am using fb board on top, so i can give away some insulating value for the strength. I am planning a 5.5" thickness of vcrete to gain height to get to a 44-45" hearth.

I did the "play like you are making pizza elbow test" and that seems about the correct height. Also, i need advice on where to end the vcrete. should it extend to the front entrance of the oven or stop at the point of the inner arch ? or is either way ok?
Tracy

[GianniFocaccia]

Re: Texman Build

Tracy,
I went the vermicrete route (3.5") under my Insboard 19. It's easy to install (8:1 vermiculiteortland) and inexpensive. 2" of vermicrete = 1" of fiber board. The compressive strength is good but the stuff dries crumbly and the edges need to be protected.

Don't worry about speed. I read about so many builders who rushed their builds and after completion say they wished they'd taken more time/care. Other than cutting my dome joints uniform (inside to outside), the single-biggest area of focus for me was maintaining consistent mortar hyration and pressing each brick into place with little or no adjustments. Yes, this takes time, but hopefully will eliminate cracking later on.
John

[texman]

Re: Texman Build

Thanks for the encouragement, guys. Besides increasing the floor insulation, i want to add some height. I am not familiar with the vermicrete and other options, but will do some research here on the forum. I know there are many options, including insulating firebrick, vermicrete, concrete and many others. Any suggestions?
Tracy
PS John, I remember reading that you removed your soldier course and started over on your oven. I had that whole thing cleaned and dismantled in about 2.5 hours. Wish i could put it back together that quick.

[GianniFocaccia]

Re: Texman Build

Tracy,
When it's all said and done your slight mishap will have translated into a quantum improvement (insulation) in the performance of your oven and you will be in a prime position to thank yourself.

I think even 1" of extra rigid insulation (50% increase) will go a long way to increasing heat retention.
John

[Lburou]

Re: Texman Build

Thanks Lee. The sun still shines and the sky is still blue. Wife isn't too POd either.
I know you added extra insulation on the floor or your oven, 3" i think.
What do you think about the going to 4" of ceramic board? I would like the added height to the oven as well as the extra insulation. I have the 2" FB board now. I have to get more mortar from Larkin and i could get extra floor board from them as well since i have to order anyway.

Tracy

If you do add the extra insulation, you and I are in the minority. Nice to have, but not essential. If you do decide to go with four inches like we did, be sure it is a rigid insulation. MY insulation was not sufficiently rigid to handle the weight of the oven without settling. My fault for not getting a proven insulator. FB board is proven. WRT oven height, higher is better for me!

[texman]

Re: Texman Build

Thanks Lee. The sun still shines and the sky is still blue. Wife isnt too POd either.
I know you added extra insulation on the floor or your oven, 3" i think.
What do you think about the going to 4" of ceramic board? I would like the added height to the oven as well as the extra inulation. I have the 2" FB board now. I have to get more mortar from Larkin and i could get extra floor board from them as well since i have to order anyway.

Tracy

[Lburou]

Re: Texman Build

Don't worry Tracy, you'll be a better person having gone through this humbling experience

I have cracks in my oven just like that right now and it works just fine. In a few days, it won't seem such a big deal.

[deejayoh]

Re: Texman Build

Tracy -
That sucks. I thought I had a bad evening - when I took off most of a chain to correct the angle error that Aidan's sharp eye caught. I always use a rubber mallet when I'm trying to get a brick out. Can't do too much damage with that!
As for the insulation - I have 2 inches of the FB board, plus an inch of this stuff under that. I think 4 inches of FB is overkill. The stuff I linked is probably a quarter the cost, and will easily handle whatever residual heat gets through the FB board.

[texman]

Re: Texman Build

oh no tracy - how frustrating - not sure i would have been able to display such stoicism if it happened to me. But as you say it will be better (and quicker) next time.

It is my own fault. I should (have) learned to leave well enough alone. Lesson for anyone reading this thread: " dont get a hammer anywhere near your dome. No matter what course you are on. If you absolutely must take a mortared brick out, cut it out with the grinder completely"

I think chipping mortar for about 2 1/2 hours helped vent the anger. It should go quick once i start again. I knocked a few chunks out of the face of some of the brick. I think i have plenty of brick if i want to replace, but i may use them as a testament to stupidity.

I think i like adding more floor insulation though, since i actually have the chance to do it again.

texidiot

[texman]

Re: Texman Build

how about just doubling the FB board and having 4"? I was reading the "what would you do different" thread and many of the post indicated that they would add more floor insulation.

[Amac]

Re: Texman Build

oh no tracy - how frustrating - not sure i would have been able to display such stoicism if it happened to me. But as you say it will be better (and quicker) next time.

[Gulf]

Re: Texman Build

That "viewer discretion" warning should have been to us all. Ouch!

2" of FB board is considered enough insulation although many have placed 2" of FB or CalSil on top of 4" of V- or P-crete.

Acid is not necessary. You have already knocked the mortar loose. Just brush off any loose particles or dust like you would with a new brick.