The Fresh Loaf

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Oven Floor

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Roo's picture
Roo

Oven Floor

It never stops amazing me when trying to find materials for the build of my wood fire oven that folks just seem to have a better way of doing things.  They take the plans look at it for a second and dismiss them as nonsense.  Happend just recently to me when trying to track down some materials but I did take pause with something a supplier of refractory cements, insulations and bricks mentioned or as he put "if I were doing this I would . . . ."


He mentioned a refractory concrete they use for shotcrete that rates up to 2500 degrees.  Instead of laying firebrick he feels that building a form and pouring the refractory concrete would make more sense.  On the face of it, it does seem to make sense, would be cheaper ( 50 bucks for 100# needing 130 # per cubic foot).  Firebricks are going for 1.75-2.50 areound here.  It rates to 2500 degrees F. and may be faster than putting down over 152 firebricks.  Never having done a WFO I have reservations about deviating from the plans however.  But in the long run I already am as I am using different insulators and the like. 


Has anybody poured their oven floor?  If so how has it been working for you?  Would you do it again?


How about the other side, why wouldn't you?  What are the cons? 


 


Tom

janij's picture
janij

I had one built last spring.  That is a really good question.  I wonder if it would really matter?  I don't have an answer for you.  But I am sure someone here does.  What plans are you using by the way?

Roo's picture
Roo

It is an Alan Scott oven.


Only thing I have thought of is if the floor fails (don't know if that is possible) the whole thing would be lost.  With Brick, you could replace that which was lost.


 


Tom


 

ClimbHi's picture
ClimbHi

"if the floor fails (don't know if that is possible) the whole thing would be lost"


'Nuff said.


It is possible. I'd ask the guy how refactory cement will hold up to damp mopping when it's at 1000 deg. F. ;-(


ClimbHi
Pittsburgh, PA

Faith in Virginia's picture
Faith in Virginia

I think the question is long term use of how refractory cement will hold up over time. The advantages to using brick is that if a brick breaks you can replace it. If your cement breaks now your patching and patching and patching every-time you get a break. I also think that brick or the small space between the brick will allow for the uneven expansion during firing to work itself out.  The cement even if you put in relief cuts will have the stress of uneven heating at firing then any stress from moping out the oven or spraying in water for steam.


Now the math average price of the brick is 2.12@152=322 ...2 bags a 50 =100 so for a difference of  222 bucks.  Do you want to risk a tried and true method for a some one suggested method.  If this does not work well then 222 bucks will be a WFO that lasts for years or one that is a headache or worse need to tear down and rebuild.


My other thought is will the cement heat at the same rate as the dome?


I know they have WFO kits that have a one piece floor but I don't know what it is made of or the process to make it strong.


I don't have the answer but I would take the 222 bucks on a % of total cost as another factor and see if it's worth the risk.

Roo's picture
Roo

Thank you ClimbHi and Faith in Virginia all very good points and taken. 


I guess I was "battling" this guy on the need for so much insulation that when he tossd out the cement idea it made some sense on the face of it.  Luckily I have the experience of you folks to sound ideas off of.


Build starts this afternoon as we have a break in the rain.  Hopefully all wil run smoothly.


Thanks again!


Tom


 

CaperAsh's picture
CaperAsh

I didn't do it but talked to some people at RHI who have built large commercial wood-fired ovens of brick and refractory mortar and the refractory poured mortar can work according to them.

Not sure about toxicity, but that is also an issue with modern firebricks, most of which are now made in China even when sold under the name of a US or Canadian firm.

Not sure about the effects of thermal cycling over time but if certain parts do break, you can get some sort of 'Green' product used in kilns to repair cracked firebrick or cement so I don't think that's an issue. If this refractory is over a normal slab, or is a large slab itself re-inforced, there is no more reason for it to collapse - I don't think - than a normal slab. Certainly if over a normal slab I suspect it's a non issue.

One advantage of refractory is that you can literally pour the whole oven, floor, sides and vault.