#1  
Old 02-27-2011, 03:07 AM
cleverdick's Avatar
Laborer
 
Join Date: Mar 2010
Location: Essex, UK
Posts: 55
Question Insulating Firebricks

I'm wondering about using 76mm insulating firebricks between the slab and cooking floor. It seems to me that it might be good because: (1) That's 3" of insulation, and (2) it avoids any risk from hazardous fibres that might exist in proprietary insulating board. My only concern is whether insulating firebrick will be strong enough to support the dome and cooking floor without crumbling, particularly when subjected to the expanding/contracting of the dome assembly.
Also, what about using insulating firebricks for the arch? I figure that would be good for keeping the front wall of the enclosure cool, but otherwise I'm not sure....
Reply With Quote
  #2  
Old 02-27-2011, 06:49 AM
GianniFocaccia's Avatar
Il Pizzaiolo
 
Join Date: Jun 2009
Location: Disneyland, CA
Posts: 1,399
Default Re: Insulating Firebricks

Insulating firebricks are plenty strong enough to support the floor, but at $3-$4 apiece it'll cost you $250 (give or take). Vermicrete has the same insulating value, can be poured thicker than 3", can support a floor and dome, and is a quarter of the cost of bricks.

Insulating bricks are very light (full of air holes) and easily abrade. They are not suitable for any part of your dome.
Reply With Quote
  #3  
Old 02-27-2011, 06:51 AM
Lburou's Avatar
Il Pizzaiolo
 
Join Date: Dec 2010
Location: DFW area, USA
Posts: 1,110
Default Re: Insulating Firebricks

Quote:
Originally Posted by GianniFocaccia View Post
Insulating firebricks are plenty strong enough to support the floor, but at $3-$4 apiece it'll cost you $250 (give or take). Vermicrete has the same insulating value, can be poured thicker than 3", can support a floor and dome, and is a quarter of the cost of bricks.

Insulating bricks are very light (full of air holes) and easily abrade. They are not suitable for any part of your dome.
I discovered one more thing about insulating firebricks....They float in water!
__________________
Lee B.
DFW area, Texas, USA

If you are thinking about building a brick oven, my advice is
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Our One Meter Pompeii Oven album is
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

An album showing our Thermal Breaks is
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


I try to learn from my mistakes, and from yours when you give me a heads up.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #4  
Old 02-27-2011, 08:43 AM
dmun's Avatar
Moderator
 
Join Date: Jul 2005
Location: New Jersey USA
Posts: 4,216
Default Re: Insulating Firebricks

Insulating fire bricks are about equal in insulating value to vermiculite concrete, meaning that you will need at least four inches below your floor. As GianniFocaccia points out, They work fine but they are not for the cost sensitive build. Like all insulation materials, they have plenty of compressive strength.

You don't need to worry about the safety of cutting insulation materials if you are using a respirator, as you should for all masonry cutting, including insulating fire bricks.

No insulation material should be exposed to the interior of your oven.
__________________
My geodesic oven project:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #5  
Old 02-27-2011, 10:17 AM
cleverdick's Avatar
Laborer
 
Join Date: Mar 2010
Location: Essex, UK
Posts: 55
Smile Re: Insulating Firebricks

Mmmm...

It's looking more and more like vermicrete is the way to go...

I suppose my initial reservation was because I always thought that heat + aerated concrete would result in an explosion!

Presumably the vermiculite gives a cushioning effect and stops it shattering!

Is that a fair assumption?
Reply With Quote
  #6  
Old 02-27-2011, 02:12 PM
eprante's Avatar
Journeyman
 
Join Date: May 2009
Location: El Cajon CA
Posts: 282
Default Re: Insulating Firebricks

Dick,
It works and its cheap, and no one will ever see it. This stage becomes almost a sickness because you can't stop thinking about the oven. No need to reinvent the wheel here. Get beyond this stage into the fun part- building the dome
Enjoy,
Eric
Reply With Quote
  #7  
Old 02-27-2011, 07:21 PM
dmun's Avatar
Moderator
 
Join Date: Jul 2005
Location: New Jersey USA
Posts: 4,216
Default Re: Insulating Firebricks

Quote:
Insulation Fire Bricks if Vermicrete is as good, they would certainly use it in furnaces but they don't.
They certainly would use it in furnaces if they fired them to 1000f. Different temperatures, different insulation.
Quote:
insulating fire bricks is that they do not expand with heat
Everything expands with heat except ice.
Quote:
anything with Portland cement has a tendersy to move with heat causing cracking in what is built on top of it.
Vermiculite concrete is perfectly stable at the temperatures we use it. Is it the best insulation? It's the best value if you're on a budget.
Quote:
in other words don't mortar your first course to the vermicrete.
Exactly right, nor your floor either. An oven is an object in motion.
__________________
My geodesic oven project:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #8  
Old 02-27-2011, 08:39 PM
Journeyman
 
Join Date: Jun 2008
Location: Melbourne Australia
Posts: 399
Default Re: Insulating Firebricks

Vermiculite is rated well over 1000f, in fact it is exfoliated at 1200c, so 1000f is a walk in the park, you just have to get the binder right, that is where cement fodue comes in to the equation at the higher temperature requirements.
The reason vermicrete is mainly used is lightness AND insulting qualities.
Reply With Quote
  #9  
Old 02-27-2011, 08:41 PM
Journeyman
 
Join Date: Jun 2008
Location: Melbourne Australia
Posts: 399
Default Re: Insulating Firebricks

Quote:
Originally Posted by Karangi Dude View Post
The one thing about insulating fire bricks is that they do not expand with heat anything with Portland cement has a tendersy to move with heat causing cracking in what is built on top of it. You need to have a floating floor and build your dome on that in other words don't mortar your first course to the vermicrete. I also beg to differ on the insulation qualities of the Insulation Fire Bricks if Vermicrete is as good, they would certainly use it in furnaces but they don't.

Doug
Vermiculite IS used extensivly in furnaces as an insulation product. It is used in both sheet form and loose fill.
Reply With Quote
  #10  
Old 02-27-2011, 08:47 PM
GianniFocaccia's Avatar
Il Pizzaiolo
 
Join Date: Jun 2009
Location: Disneyland, CA
Posts: 1,399
Default Re: Insulating Firebricks

A UK firm (Vitcas) manufactures vermiculite board as insulation and strangely enough, firebrick replacements in wood stoves. Rated to 1000*C, I think this board is a little overkill for our application but the fact that we can manufacture such a cost-effective
insulative layer from common materials purchased from our local box store is way cool.
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
Why not insulating firebricks for hearth insulation? kebwi Tools, Tips and Techniques 20 12-12-2009 04:52 PM
FB insulating board AND insulating concrete? Wineguy Pompeii Oven Construction 1 10-25-2009 11:44 AM
Are these firebricks the right weight? Nick Pompeii Oven Construction 2 09-27-2007 09:40 AM
Super Isol vs insulating firebricks readie Getting Started 2 06-15-2007 10:25 AM
How they make insulating firebricks james Getting Started 4 10-09-2006 09:51 AM


All times are GMT -7. The time now is 01:39 AM.

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