The hearth questions and progress pictures

[asudavew]

Originally Posted by George T

Thanks Guys. I have looked at lots of pictures
First the FB board seems price at an insane price if I am understanding....I have a 42 inch oven and the directions say 4 pieces....$280 plus shipping.

I bought my perlite for $54 and two bags of portland $17 or total $71. I have seen some say it was almost the same price for FB board....but I could not see it.

Asudavew....do you think building the form was worth the time? What were the advantages from your perspective.

Thanks.

To me it was.
I didn't want the huge hearth... I like the three and a half inch hearth.
I have yet to finish it all out, but if I had a do over.. I would have taken more time curing. Cut the arch bricks for a really tight fit. And made the insulating layer 5.5 inches instead of 3.5

Hope this helps

Dave

[mfiore]

Dave, if you could do it over, would you still have used the perlite/concrete, or an insulation board?

[asudavew]

Originally Posted by mfiore

Dave, if you could do it over, would you still have used the perlite/concrete, or an insulation board?

THE more insulation the better.

Insulation board...that's how I would go..............I seem to lose heat from the hearth.

ie. So the tops cook fast... and the bottoms.. not so fast.

More insulation on the hearth is the way to go.

MORE>>> MORE>>> MORE

I don't think you can do to much on the bottom of you WFO

[RTflorida]

Although I've not really had any issues, I will second Dave's comments. I too only used Vermiculete under the hearth - 4" in my case. Never an issue making pizza, but the next day when I am slow roasting or smoking - the variance between dome and hearth is usually about 50 degrees (the hearth being cooler). I think using the board or simply more verm. under the hearth would go a long way in having closer temps.

RT

[SpringJim]

I will also comment on the original question....if you can do both the structural and insulating pours on the same day, do it....I think you will have a better structure....keep it wet! (and only one cleanup event)

....might also be good to have Daves form ready to place on the structural layer to make that second pour easier!

XJ

[dmun]

Most things in life are a time/money compromise. Since vermiculite and portland aren't free, I think the advantage tilts to insulation boards. You might look into insblock19, which may be available locally. That's what I used, and it works fine.

Check with local pottery and kiln suppliers, they might have it for less money than Harbison-Walker sells it for.

[DrakeRemoray]

I did not have any trouble getting a level floor using a wet fireclay mix troweled on with a tile setting trowel on top of my vermiculite layer. That said, I am sure it would be even easier using FB board.

Originally Posted by RTflorida

Although I've not really had any issues, I will second Dave's comments. I too only used Vermiculete under the hearth - 4" in my case. Never an issue making pizza, but the next day when I am slow roasting or smoking - the variance between dome and hearth is usually about 50 degrees (the hearth being cooler). I think using the board or simply more verm. under the hearth would go a long way in having closer temps.
RT

Ditto! I used vermiculite only and do find that my floor is about 50 degrees cooler the next day, but I have always attributed that to the fact that the floor has less mass than the dome...

Drake

[George T]

Thanks for the thoughts. I poured my Perlcrete today. I was thinking....only the thinkess of a 2x4...or 3.5 inches. Should I be concerned regarding not having a full 4 inches of Perlcrete? It seemed somewhat crumbly I hope it sets up. I think I got it good and level!

Thanks again for all the ideas. The forum is a great help. I will post some more pictures tomorrow. Work on the fireplace tomorrow.....hopefully start my igloo on Sunday.

[thebadger]

George T,

I only used a 2x4 as well (3.5") but I also used the cal sil board on top. I don't think you want to go to much less than 4 if you only using perlcrete... Not that it wouldn't be okay but you want to retain as much heat in the floor as possible.

It is strange stuff. As long as you stick to the formula you should be fine.

Look up the thread on hearth height. I have 4 courses of block plus an add'l 12" of material on top for a total height of ~41" and I wish my hearth was a little higher (I stand 5'10")

Thanks
Dick

[George T]

Test Photo.

<a href="http://picasaweb.google.com/ghtaylo/GeorgeTSPizzaOven/photo#5211852083667468338"><img src="http://lh5.ggpht.com/ghtaylo/SFQ320ThADI/AAAAAAAAAEs/iiVc9XTxfBI/s144/IMGP1871.JPG" /></a>