pompeii oven construction began today

[Marcel]

# 73

(M) Paul, I'm not really concerned about the "slip plane" but about a water shield and to a lesser degree, a smoke shield. Had I worried about a slip plane, I would have placed the foil between the bricks and the refractory cladding layer where cracking could have structural ramifications. If the perlcrete cracks, and I doubt that it will, there is no real harm done. Still, that's a rhetorical response as I may need to give up on the foil anyway for lack of adhesion. I want to "move forward" but I need to await at least 3-4 days of predicted dry weather.

Ciao,

Marcel

[aikitarik]

Originally Posted by Marcel

(M) Tarik, if your last post was not a typo, I think 12:1 would not offer enough adhesion. I used perhaps a 7:1 and could not get it to stick to the aluminum foil (hardly a surprise); but even after adding Paul's chicken wire, it fell off. Cement is cheap but perhaps you simply want your cladding to be as "insulatory" as possible.

Marcel,

I am basing the decision for using a 12:1 ratio on a post from Alan wherein he suggests it (for the Bread Builders oven) IFF you have enough structural support.

Since I am merely coating the oven, I figure this will be no problem. If I go with this approach, I don't believe I will have the adhesion problem you're describing as I will simply use some hardiboard forms in addition to the chicken wire.

Tarik

[paulages]

but I need to await at least 3-4 days of predicted dry weather.

good luck! ... so you'll be "moving on" next july?

[james]

What about renting a big tent to go over the oven so you won't have to wait for the impossible?

James

[Marcel]

#74

(M) What can I say to Jim and Paul
Who build their ovens dry and tall
Not like mine, so wet and small

Our weather here is not like Gaul
It rains like Hell here in the Fall
But even then I'll have a ball

It's wet here now, and that's my call
Back to work, I musn't stall!
Round the dome I'll build a wall.

Burma Shave


Ciao, Marcel

[ColonelCorn76]

Originally Posted by aikitarik

Jim,

I'm just about at this stage... would it really be more efficient to do the loose fill and no perlite concrete layering? I was planning on a 12:1 mix, about 4-5 inches thick and than using loose fill around that.

My main concern was to prevent perlite dust from getting into the oven and to add a little more structural support around the chimney.

Tarik

Using a foil wrap in between the perlite mix & the dome should keep any perlite dust from getting in the oven (shouldn't be a problem anyway but no big deal to eliminate the possibility). The 12:1 mix is probably too dry to use -- 6:1 or 8:1 is fine. Using loose fill on that is probably counter-productive (or at least past the point of diminishing returns). 5" of perlite concrete is the insulating equivalent of about 9' of concrete. For all practical purposes you're not going to need more then that to be able to store enough heat to cook - even overnight.

Jim

[ColonelCorn76]

Originally Posted by Marcel

(M) In the quote above, that builder, I believe, suggests putting the foil between the firebricks and the layer of refractory mortar. In my case, I will have an insulating layer of perlcrete so I do want to reflect heat back to the firebrick. I'm not sure that foil would work as a heat reflector, absent light but the thermal engineers who read this may be able to shed light on that question.

The foil can be a slip plane between the outer mortar "butter" and the insulating layer and the dome due to the differing thermal reactivity of the two materials. If you're using a mix of materials for the insulating layer (e.g. a layer of refractory cement and then one of perlite/vermiculite) then the foil can be used between the refractory layer and the perlite/vermiculite layer simply due to the thermal shock resistance (to cracking) of the refractory cement.

Foil is an optional component by the way and not really necessary. More useful for the fully exposed igloo style oven then the doghouse style.

Jim

[paulages]

the roof is ready to plant...just gotta put some soil up there.

after framing the wooden roof on top of the durarock, i used 2" x 8" lumber to frame in a "curb" around the edges. then i layed pond liner in, cutting a hole for the chimney, using a #8 metal roof style hi temp. chimney flashing to seal around it. folding the liner over the edges, i tacked it to the outside of the frame with roofing nails, and used gable flashing to hide it. at the bottom, the pond liner just spills over into the gutter, and i used a piece of "trex" (recycled plastic 2" x 4") as a soil barrier. a 1/2" gap was left at the bottom for drainage, and aluminum screen was nailed to the trex to help keep soil from eroding through. this was backed with gravel.



top view of gutter line:


showing new overhang...


...by the way the wooden part on the left is not new, but rather part of the pre-existing kiwi arbor, that will now function also as a rain shelter from the backdoor to the oven overhang.

[aikitarik]

I must say, very sexy!

[paulages]

perhaps the best multi-use function i have found yet for a giant stone structure in the backyard. seriously, i have to keep convincing myself i'm not crazy everytime i walk up and think, "holy "@^%#" that thing is huge!"