Newbie from Eastern Washington State

[combustix]

Lill Dave thanks for the tip, may have to come out and see as this will be a major project that I have not tried before. First stab at masonry did not come out so well, but at least I have some experience now. On the vermiculite or perlite, I take it you smear this over the dome? Is this before the FB planket or after. Thanks for being a resource and will be in touch once I get the project under way.

[azpizzanut]

Hi combustix,

Properly mixed vermicrete or perlcrete is wet but unlike concrete or mortar. It is more like milk over dry cereal. It even sounds crunchy when you mix and apply it.

Here are some tips that I picked up from the forum. 1. You don't "pour" perlcrete or vermicrete and you don't smear it because it will compress. The texture is not really pourable. You shovel it onto the base or pack it by the handful against the finished dome. 2. you can get too much water in the mix and notice it washing away the Portland cement from the perlite or vermiculite. If there is a pool of water in the bottom of your mixing tub then you added too much. You can also vary the ratio of insulation to Portland cement, 5:1 for the base and up to 10:1 for covering the dome. It will be crumbly but eventually set-up strong. It has acceptable compressive strength but is not like cured concrete at all.

There are a couple of options for applying perlcrete/vermicrete insulation on a finished dome. You can place 3"-4" over the dome bricks like an igloo and then apply blanket or other roll insulation or, you can apply the blanket first then a layer of chicken wire over the blanket to hold 3"-4" perlcrete. Folks who opt to do the blanket/perlcrete method also cover the dome with stucco as a way to complete the building project. On my build #1, I put perlcrete over the dome then a layer of commercial rockwool insulation then built an enclosure around the base and filled it with loose perlite.

Another option would be to wrap the dome in FB blanket then build an enclosure around the dome and fill it with loose perlite or vermiculite. You don't really need cement based insulation on the dome at all and some might argue that all you need is 3" of blanket then a weather cover like stucco or a frame enclosure. More insulation doesn't hurt a thing though.

Cheers,

[Lill Dave]

Originally Posted by azpizzanut

Hi All,

OOOOOH ! A new build.

I used block fill Perlite and didn't know there was supposed to be a problem. It mixed with Portland cement just fine. The package gave information about masonry block filling so I am sure that was its intended purpose. If the package also says something about a coating to improve flow characteristics then you may want to try a batch to see if it mixes ok.

Look at landscaper websites to source Perlite. It is used at golf courses and other large users including plant nurseries. I covered the dome of my 36" Pompeii with vermiculite from a landscaper supply. It is twice the price of Perlite but I wanted to try it. I saved on cost by enclosing the dome with aluminum window screen with a 4"-6" spacing. No point in filling the far off voids in the corners, etc. when it doesn't do any good there. See my build #2. View it as a slide show.

Cheers,

I mentioned the oatmeal question to my wife and she said that always means wet, now I know.
Thanks for the info, my second oven too is having it's second fire today for it's breaking in period.My first oven was a barell type and not insluated enough , didn't make that mustake on number 2.

[Lill Dave]

Originally Posted by combustix

Lill Dave thanks for the tip, may have to come out and see as this will be a major project that I have not tried before. First stab at masonry did not come out so well, but at least I have some experience now. On the vermiculite or perlite, I take it you smear this over the dome? Is this before the FB planket or after. Thanks for being a resource and will be in touch once I get the project under way.

Actualy with 3to4 inches of one of these products you don't really need the blanket, but everyone says you can't realy use to much insulation.My floor has 5and one half inches of perlite.

[combustix]

Thanks for the info, I think when I get home from work next week I am going to start sourcing my materials, I do have a brick place in burlington I need to check out. Nicce to know there are resources to fall back on if my dome comes out square
Dave

[Lill Dave]

I think I told you Seattle sand and gravel for supplies , It' salmon bay cement in the Ballard area.
For bricks , Lime for one of the ingrediants to mix your own refractory cement, sand and they also have fire clay.