#11  
Old 09-06-2008, 06:55 PM
brokencookie's Avatar
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Location: Pacific Northwest
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Default Re: Greetings from NY

Here is a calculation straight from the horse's mouth - James ( not to be confused with the horses other end )

"For oven width, take the exterior width of your oven (oven floor, plus oven wall width), then add 10" for your insulation (1" insulfrax and 4" vermiculite), then add the thickness of your enclosure walls (1/2" for an Igloo, 2" for a metal stud wall, 4" for a concrete block split, etc.)"

"Standard" fire bricks come in a wide variety of sizes. I believe the most common size in the US is 9 x 4 x 2.5 inches

Check with your local supplier for exact dimensions.
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Last edited by brokencookie; 09-06-2008 at 06:56 PM. Reason: fat fingers, small keys
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  #12  
Old 09-21-2008, 07:10 PM
Serf
 
Join Date: Sep 2008
Location: New York
Posts: 21
Unhappy Re: Greetings from NY

I need a bit of help folks.... James? Anyone?*Vermiculite Related Question *

I have just completed the Hearth in two stages. First stage was the 3.5" Rebar Reinforced Concrete which cured for a week. Then I added the 4" Vermiculite Slab. I am a little concerned however in respect to the Vermiculte slab and need someones advise.

I laid the Vermiculite Slab on a Saturday Morning and it is now Sunday Evening and the Slab still feels "Damp and Moist" unlike the Concrete Slab which had dryed out by the next morning. Further, in looking at the photo's from the Pompeii Plans, the Vermicultie was gray and lumpy. My Slab is light brown (((a sand color ))) and has a smoother texture.

Just to make sure I give you all the information you need, the plans called for 5 Parts Vermiculate and 1 Part Portland Cement. My interpertation was 5 Buckets of Vermiculate to 1 Bucket of Portland Cement. A

Also the plans called for 2 x 4 cu ft Bags of Vermiculate and one bag of 94 lb. of Portland. I ended up needing 3.5 Bags of Vermiculate and 1.5 Bags of Portland for a 62" x 62" x 4" Slab. Not sure if these details are important but I thought I would share.

Can someone put my mind at ease??? The last thing I want is to take the forms off only to discover that the Vermiculate Slab is not Strong enough to support my oven.
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Greetings from NY-vermiculite-1.jpg   Greetings from NY-vermiculite-2.jpg  
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  #13  
Old 09-21-2008, 08:27 PM
Il Pizzaiolo
 
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Location: Tampa, FL
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Default Re: Greetings from NY

Your mix sounds fine, I too used a bucket to measure (the same 5-1 ratio).

As for the color, not sure of variations.....portland is usually grey, vermiculite a sandy brown (at least mine was) so I would think any hue between light grey and light brown would be possible.

the consistency - it will feel damp and moist for several days and the glossy/slick look will dissipate along with the moisture - looking even more crumbly as it drys out. From your pics, things look fine to me (just a little more brown in color than mine).

I have two questions - 1) Did you use agricultural grade vermiculite? That is the one you want. There is a type of vermiculite that is treated with silicone to be used as wall insulation...not good, as the silicone does not allow adhesion with the portland cement. 2) What size vermiculite - fine, medium, or course? Naturally, this would effect the the appearance; I don't think it affects the strength or insulating value. In my shopping I found medium to be the most readily available (and what I used).

One last point, don't be in a rush to take off the forms. Give the vermicrete at least a week to cure before proceeding and you should be good to go.

RT
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  #14  
Old 09-22-2008, 02:06 PM
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Location: New York
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Default Re: Greetings from NY

OK.... here it is...

The Bag of Vermiculite has the following information, and for the life of my I don't understand why I didn't pay closer attention to this sooner.

A-TOPS Vermiculite Masonary Insulation
Water Repelant For Block & Cavity Walls

No mention of any of the other information you requested...

From your last posting I would say i am screwed for lack of better words.

Can anyone tell me if I will need to REMOVE this layer and reapply?
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  #15  
Old 09-22-2008, 04:10 PM
Il Pizzaiolo
 
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Location: Tampa, FL
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Default Re: Greetings from NY

I wish I could guide you further, the water repellent vermiculite is beyond my area of expertise. I followed the recommendations of several other forum members and stayed away from it. Hopefully someone who has actually used it can share their experience.
My latest guess is this is the reason your insulating layer appears more brown than grey....the portland not binding to the vermiculite has allowed most of the portland to settle to the bottom allowing the vermiculite (which is more brown in color) to rise to the top. Again, having no experience with this situation, I don't know how detrimental this is...I will stop short of telling you to do it over, until someone else chimes in...but I would consider it.

RT
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  #16  
Old 09-22-2008, 08:38 PM
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Join Date: Sep 2008
Location: New York
Posts: 21
Default Re: Greetings from NY

Thanks...

If anyone can give any information that will clear up the below questions it would be most helpful. I have the same questions posted in other areas and wishing someone can assist.

After I poured my hearth, I noticed that the the Bag of Vermiculite has the following information. I'm upset that I didn't notice prior to pouring.

BRAND:

A-TOPS Vermiculite Masonary Insulation
Water Repelant For Block & Cavity Walls

Need a little help here guys...


1) Did I screw up and use the wrong material?
2) Will the insulating Hearth function as designed?
3) Will this material HOLD or will it crumble?
3) There is no mention of Asbestos but bag does say to wear a mask?
4) Will I need to REMOVE this layer and reapply? ((YIKES))
5) Does anyone have any other solutions should Hearh be a flop?
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  #17  
Old 09-23-2008, 02:44 AM
Frances's Avatar
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Location: Allschwil, Switzerland
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Default Re: Greetings from NY

I think the answer here would have to be that we just don't know... I don't think anyone has used the treated vermiculite before.

The question is, how can you test your vermcrete layer to see if you have to do it over or not.


I would suggest you wait for a couple of days and then maybe walk around on it, to see how it holds up. Check how crumbly the top is. It should feel something like cork. Then ... light a fire on it? Hold a blow torch to it? How do you test insulation for oven buildability?
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  #18  
Old 09-23-2008, 06:50 AM
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Location: New York
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Default Re: Greetings from NY

Ok... it's my turn to give back on this one...

I contacted the Vermiculite Manufacturer (( A-TOPS in PA )) and asked the questions and would like to share the answers with the Forum to keep some other poor sap from having their oven dreams turn into a nightmare. TFYI there is also another manufacturer of Vermiculite called SCHUNDLER in NJ.

1) ASBESTOS: Per A-TOPS and SCHUNDLER products are Asbestos Free

2) TYPE and GRADE: From what I was told by the manufacturer, The Pool Mix is the best mix for the oven project, however the only difference between the Pool Mix and the mix that I purchased ((Vermiculite Masonary Insulation - Water Repelant For Block & Cavity Walls)) is the Grade. Pool Mix is fine and the Block & Cavity mix is coarse. A-TOPS also told me that the name is misleading "..Water Repelant for Block & Cavity..." and that the vermiculite is Untreated. I wouldn't risk it again.

What is VERY IMPORTANT is that the Vermiculite Mix that you purchase is UNTREATED and PURE in form.

Hope this helps everyone.

If I where anyone else reading this string for information, I wouldn't risk purchasing the mix that I bought. Take the time to read the fine print and ask the questions in respect to the application you need. Contact the manufacturer and triple check. The manufacturer told me that my mix would work ... that is to be seen.

Thanks to you all.
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  #19  
Old 09-23-2008, 08:32 AM
egalecki's Avatar
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Location: Virginia
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Default Re: Greetings from NY

Whew, glad your mix didn't have the silicone treatment.

Vermiculite concrete is weird looking stuff, and the texture is strange too. It never, ever gets to looking or feeling like the other concrete, so don't expect it to. At best, it looks sort of like solid oatmeal. You can pick little crumbly bits up and smash them with your fingers. You can worry around the edges like a mouse and break it up. BUT, when you start laying things on the top, it's tough stuff in compression.

I'll try to get a picture of mine for you, but I have to find the camera first. I cleaned and now I can't find anything...
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  #20  
Old 09-23-2008, 09:04 AM
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Default Re: Greetings from NY

Oh hey, good news!

Don't worry a bit then - for some reason I ended up with the coarse grade too, and it works a treat.
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