Vermicucrete above or below Kaowool

[jcg31]

Having learned the miracle of insulation these last two weekends with the curing fires, I have decided to add a layer of vermicucrete to the outside of the dome. I see in posts that some add it directly to the dome, while others are laying down the ceramic blanket first and then putting down the vermicucrete over the blanket. Does anyone know the relative benefits of either approach. Does applying directly to the dome provide more structural support?

Thanks for any thoughts.

Jim

[dmun]

Re: Vermicucrete above or below Kaowool

I put the blanket outside the brick dome, and covered it with vermiculite concrete. The perlcrete has no structural strength, so I don't think it will help with anything structural, except maybe supporting the stucco on the outside of the dome. Besides, the blanket is the much better insulator, and you want it where it will do the most good.

[NanyukiTom]

Re: Vermicucrete above or below Kaowool

Hi JCG31,

I live in Kenya and have been unable to find any sort of insulating blanket to put around the dome. I finally opted for 6 inches of vermicucrete. It seems to be working fairly well. I was a bit concerned about expansion and the need for a woven insulation blanket but the vermicucrete seems to be working just fine.

I agree that it adds no structural elements to the whole program. It's acutally a bit of mess to work with. I ended up "sculpting" a layer of chicken wire (1/2" opening) about 6 inches above the dome outer face and then filling the space between the dome and the chicken wire with the vermicucrete. I don't see how it ever would have stuck without the chicken wire to hold it in place.

Tom T

[gjbingham]

Re: Vermicucrete above or below Kaowool

I think dmun has it correct. Blanket first, then vermicrete.

[CanuckJim]

Re: Vermicucrete above or below Kaowool

JCG,

Have to add my assent to what Dmun and George have said. All the FB installations I've done are assembled with the blanket(s) first, then chicken wire, then wet insulation coating, whether vermic/cement or something else.

You won't get any structural advantage by using the wet coat first, and the blanket(s) is/are the better insulator to have directly against the dome.

Jim

[jcg31]

Re: Vermicucrete above or below Kaowool

Blanket first, then vermicucrete. Done! Thanks all.
Jim

[RCLake]

Re: Vermicucrete above or below Kaowool

Jim, I know you are installing 50sf of 2" blanket which probably means you will have 3" coverage over your dome. If you are planning on adding vermiculite over it is it because More Is Better or have you noticed what you have so far is lacking?
As you know I have 50sf of 3"(4-5" of coverage) that I'm hoping will be enough, but I don't know.

[jcg31]

Re: Vermicucrete above or below Kaowool

No, I am just buying the "you can never have enough insulation" thinking. But I had the top outer surface of the dome to 725 degrees this weekend (inside top was 850-derees). The wool on top of the dome was merely warm, I am certain if I had two layers in place the wool would have been entirly cool to the touch. You should be fine with what you have.

Jim

[RCLake]

Re: Vermicucrete above or below Kaowool

Jim, thanks for the info.

If you are at 850 in the dome and day 5 goal is 700 have you started cooking yet?

[mfiore]

Re: Vermicucrete above or below Kaowool

Perhaps a silly question from one who hasn't started building yet, but if the blanket is a superior insulator, why skip the vermiculite and put down more blanket? Does the vermiculite serve some other purpose?

[thebadger]

Re: Vermicucrete above or below Kaowool

Mfiore,

You have a lot of options:

All Blanket,
All vermiculite or an equivalent
A mixture of both - the route I'm going to use.

I think it really boils down to cost but my understanding is the blanket is superior (the plans detail which ratio to use of each). James cells a new less expensive FB blanked that I just purchased.

I'm actually planning on using 2 inches of blanket then vermiculite to fill the void. I'll prob end up using way more vermiculite but I would rather have too much.

Thanks
Dick

Hey, I haven't built yet but I feel comfortable answering some questions given I've read the plans so many times. Don't ask where I keep my copy.

[dmun]

Re: Vermicucrete above or below Kaowool

The vermiculite concrete is about a quarter the price of high-tech insulating materials. It also fits into cracks and voids, and forms a smooth surface, which the overlapped blanket does not.

[Frances]

Re: Vermicucrete above or below Kaowool

Don't ask where I keep my copy.

...bedside table, right?

Using the digital version as a screen saver at work would be pretty good, too.

[Frances]

Re: Vermicucrete above or below Kaowool

Hey, I just noticed, I'm master builder now!!! Wow, when did THAT happen??!

[asudavew]

Re: Vermicucrete above or below Kaowool

Hey, I just noticed, I'm master builder now!!! Wow, when did THAT happen??!

About 9 posts ago! give or take...

Congrats Frances, but I already knew you were a master builder.

(and Chef, I might add)

dave