#1  
Old 06-22-2009, 11:15 AM
Serf
 
Join Date: Sep 2007
Location: manitoba, canada
Posts: 10
Default vermiculite insulation

i am in the process of building an alan scott design oven. i just poured the concrete over the dome this past weekend. my intentions are to eventually clad it with grapefruit size granite stones as a finished coat. my question is regarding the vermiculite insulation. is it best to pour the vermiculite dry first and then cover it with a vermiculite/portland mixture or just use a damp vermiculite/portland mixture with venting right off the bat? thank you in advance.

need real bread,
bernie
Reply With Quote
  #2  
Old 06-22-2009, 02:25 PM
cynon767's Avatar
Apprentice
 
Join Date: Dec 2008
Location: Sacramento, California
Posts: 230
Default Re: vermiculite insulation

General consensus around here is that it's best to mix the vermiculite and portland thouroughly while dry, add water, then apply the damp oatmeal-consistency mixture. Check out some of the other threads, and look at the photo section on insulation for some good illustrations.
__________________
-jamie


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #3  
Old 06-23-2009, 01:07 AM
Apprentice
 
Join Date: Feb 2009
Location: Australia
Posts: 118
Arrow Re: vermiculite insulation

Gee,
how much thermal mass do you want in your oven?
The bricks in your barrel vault are probably 4 1/2" thick, with a layer of concrete over that to increase the mass, you now need at least 4 to 5" vermiculite cement to insulate the vault AND then a cement layer to hold your rock in place. If you don't do this, you will need all day and a truck load of wood to get it hot and it will drain the heat out and cool down quicker than it took to get hot without being well insulated.
I would not have put the cement layer on, but a thermal superwool or similar insulating blanket or 4" vermiculite insulation straight onto your vault bricks and then your final finish to accommodate your rocks.

Rastys
Reply With Quote
  #4  
Old 06-23-2009, 06:28 PM
Neil2's Avatar
Il Pizzaiolo
 
Join Date: Oct 2006
Location: Vancouver Island
Posts: 1,374
Default Re: vermiculite insulation

The Alan Scott design is more of a bread oven, I think. They generally have more thermal mass that a pizza oven.
Reply With Quote
  #5  
Old 06-24-2009, 08:37 AM
Serf
 
Join Date: Sep 2007
Location: manitoba, canada
Posts: 10
Default Re: vermiculite insulation

thanks for your helpful replies. i was concerned about loosing insulating value when wetting the vermiculite. as for the thermal mass, i did not even think of the outer stonework adding thermal mass. i considered it cosmetic being on the outside of the insulation. up here in manitoba, canada it may be a blessing. soon, i should have some bread.

thanks again,
bernie
Reply With Quote
  #6  
Old 06-24-2009, 05:36 PM
Apprentice
 
Join Date: Feb 2009
Location: Australia
Posts: 118
Arrow Re: vermiculite insulation

Bernie,
if you don't insulate well your vault, then your decorative stone outer surface will add to your thermal mass, absorb your oven heat and release it to the atmosphere.
By all means do your rock finish layer but I would put at least 4" vermiculite cement under it to provide your insulation.
Mix your vermiculite 6 pts to Portland cement 1 pt to a porride/oatmeal consistency.
I mixed mine in a wheelbarrow with a flat bladed fork and then carefully added the water till it held together in a ball when squeezed, a bit like a snowball. Little if any water should be squeezed out of it when squeezed. It is quite unusual to mix as the added water washes the portland off the vermiculite but be careful not to put too much water into the mix and that it well mixed before applying it to your vault.

Rastys
Attached Thumbnails
vermiculite insulation-mixed-vermiculite-.jpg   vermiculite insulation-mixing-vermiculite.jpg  
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Vermiculite only insulation? shepster Pompeii Oven Construction 17 09-23-2013 03:24 PM
fiberglass insulation between concrete and vermiculite insulation layer pabsey Introductions 6 07-19-2009 11:47 AM
Insulation question - loose or solid vermiculite covering? jammyweb Newbie Forum 12 06-23-2009 04:57 AM
Vermiculite Concrete hearth insulation jrparks Pompeii Oven Construction 4 01-09-2009 04:35 PM
Bedding brick hearth to vermiculite insulation nissanneill Getting Started 5 05-22-2007 07:41 PM


All times are GMT -7. The time now is 09:19 PM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
© 2006/10 Forno Bravo, LLC