A Newbie's photo documentary Page 01
If you are a Newbie, know that there are many ways to build a successful wood burning oven. The documentation that follows is only one way and you will probably find ways to improve upon the suggestions that follow. I hope to remember to put the mistakes in red font but read them anyway so you don't have to repeat mine.
This "monologue" is for building what is commonly called a Pompeii oven. It has a circular foot print and is essentially a modified hemisphere dome. It looks a bit like an igloo. I chose that design over the rectangular footprint because as built it uses less thermal mass and so it heats more quickly.
This forum allows only 5 images &/or URLs per posting so because I reference 2 URLs below, I can only offer 3 images with this page. If you want to view all of the images, you will need to click on an external link:
But there are only images and no comments there so that is less helpful.
This first image shows the excavation for the foundation slab. My first mistake occurred with the grading. You can see spaces under the wood frame. If I had graded the earth more carefully I would have saved quite a bit of concrete.
In image #02 it shows that I laid out some vinyl sheeting prior to the pour to minimize water seepage into the foundation slab. The pipes sticking up are an elective if you want to bring in water &/or electricity at some later date. The size of this foundation is 10’ x 10’ and is much larger than the minimum.
If you want only enough of a foundation to support your “stand”, consider a minimum of 6’ x 6’. The thickness of the slab is 5 ½ inches so most builders use nominal 2”x6” boards. Re-bar was added to the slab but doesn’t show here.
If you can count the concrete blocks in the 3rd image you’ll see that there are 4 ½ blocks on a side. This is large enough to accommodate a hearth slab of almost 6 feet on a side. That Hearth Slab will support a 42 inch dome. I filled alternate cores with vertical re-bar, and standard ready-mix concrete. My design differs from that of most builders in that in stead of using a piece of angle iron to span the wood storage area and locate it under the 4th course of blocks, I chose to locate my support at the very top of the Hearth Stand.
I'll post additional pages if I get any favorable responses from Newbies.
Yes, Marcel, please post more images and your step by step progress report. This is extremely helpful!
I hope to both build my own Pompeii oven AND figure out why the horn is inside your chimney. Patience required on both fronts, I anticipate.
Many thanks again,
A Newbie's photo documentary Page 02
(M) Maria, since you requested more postings, here come 5? 4 ? more URLs with commentary IF the images are viewable?
The first image is a close up of the reinforcing steel rectangular "tube" over the wood storage area. This is the point of a fairly important decision. Using no L shaped angle iron to support the 4th row of concrete blocks helped me gain easier access to the wood storage area, and saved the weight of those bricks but it made the construction of the plywood supports for the Hearth Slab a bit trickier; I had to notch the plywood to allow it to extend to the front of the front wall, something which would not have been necessary had I opted to use L angle iron and the extra concrete blocks. If you support the span from the top, as I did, you probably won't need as heavy a steel support as I used. I was able to easily find one at a nearby scrap steel yard. You could probably get by with 1/4" flat steel.
The next image shows some of the begining support for the plywood - particle board - wafer board - or whatver. I had read in someone else's posting, his regret that he had not sloped the wood storage area, to prevent rain water build up, until after he poured his hearth slab! 'Good', I thought, I'll learn from his mistake not realizing I overlooked the resulting angle cuts needed by my vertical 2x4 supports where they rest on a now sloped floor! You are probably going to have less trouble in the long run by first pouring the Hearth Slab, building your block stand, and then crawling under it and only then pouring a 1/2" slope to the front, even as awkward as that would be.
This image skips a few from PhotoBucket and shows the nominal 2"x6" boards that will support the Hearth Slab pour. If you look closely at the left board (it actually measures closer to 1- 1/2" x 5- 1/2") you will see that it bows out. Here I made another "mistake". I decided it would be easier for me to rest the side boards about 1/2" on top of the concrete blocks. If I had it to do over I would have invested a few more dollars and bought 2" x 8" side boards and rested them against the vertical concrete block walls. Later, I had to do some time consuming mortar patch work to fill the lip created by the boards resting on the blocks rather than supported from underneath!
The fourth image shows some unnecessarily long side boards framing the Hearth pad floor. I purposely used these long ones as
1- I hoped to later use them in their full length on another project, &
2- I was unsure at that point of I was going to have a cantilevered - overhanging section where the baker would stand.
The last image in this posting, and the last until I get another request for more, shows one way to have supported the boards without resting them on top of the concrete blocks. If you choose to use a similar system you may find it easier and perhaps stronger, to angle the supporting 2x4 and use at least 2 or 3 for each length.
(M) P.S. There is so much information that a Newbie might want that is impractical to include. As an example, the red and black lines on the facing board are guide lines, suggested by Jim Hatch, or James Bairey to help the builder with a 2 part pour, and the location of very important Re-Bar!
(M) The lines need to be on the inside, but I drew them on both sides for clarity of reference.
(M) The order of the 2 different pours is still under discussion as is their respective thickness. I went the conventional route of first pouring the insulating concrete (write me for proportions if you don't find it elsewhere) and then topping off with the stronger Thermal layer of Refractory mortar. Space, here, precludes the practicality of a thorough explanation of each step.
Page 03 of A Newbie's Photo Documentary
(M) I had to leave out the image to the descriptive text which follows here, next. The easiest work-around was to simply include that image as a new post with a Copy-Paste from the preceding. So here it comes, I hope!
(M) "The first image is a close up of the reinforcing steel rectangular "tube" over the wood storage area. This is the point of a fairly important decision. Using no L shaped angle iron to support the 4th row of concrete blocks helped me gain easier access to the wood storage area, and saved the weight of those bricks but it made the construction of the plywood supports for the Hearth Slab a bit trickier; I had to notch the plywood to allow it to extend to the front of the front wall, something which would not have been necessary had I opted to use L angle iron and the extra concrete blocks. If you support the span from the top, as I did, you probably won't need as heavy a steel support as I used. I was able to easily find one at a nearby scrap steel yard. You could probably get by with 1/4" flat steel." (M) Or perhaps several lengths of re-bar across that opening:
cinder block bases
OK I have one question, why do a lot of you seem to dry stack your cinder blocks? I dont understand other than it is easy to level. I dont have that option as mine is going to be tied into my wall that intersects the oven base.
Filled alternate cores are not really dry stacked. #70
(M) Hey, Chad!
What you see is only the begining of a chronological pictorial documentary of my oven building process. Later, if other Newbie's (or you) so request, I'll add images to address such questions as you posed below:
(C) "OK I have one question, why do a lot of you seem to dry stack your cinder blocks?"
(M) The operant word in your post is probably "seem". I filled alternate cores with re-bar and concrete. That isn't evident in my documentation to this point. I believe that virtually everyone who builds a hearth stand omits the mortar line between concrete block courses but then fills many cores with re-bar and concrete. IMHO the mortar lines such as found in standard brick work for chimneys would contribute little to the overall stability of the wall if the cores were already filled with concrete.
(M) Do I take it that you would like me to post an additional 4 or 5 images?
dry stacking and filled cores
I think I have looked at your pics before Marcel, but please post them, it is always good to see how others do their stuff.
OK I see now how you are tying it all together. That works for me. Still does not work for my application, but that is OK too.
I'll add 4-5 more images #71
(M) Your last post, Chad gave me the idea that a builder could have the vertical rebar used in alternate cores stick up about 4-5 inches over the tops of the concrete blocks. These re-bar extensions would help to locj everything together after the Hearth Slab pour.
(M) I found the next sentence in the text of the 3rd photo: "I filled alternate cores with vertical re-bar, and standard ready-mix concrete."
(M) Since you requested:
(C) "I think I have looked at your pics before Marcel, but please post them, it is always good to see how others do their stuff."
(M) I'll try some more, below. This is a fair amount of work so only when I get requests for more will I add. This is supposed to be helpful and if Newbies don't want or need it, I have no investment in developing this
The next four images are located elsewhere on this Forum. It may be redundent to reproduce them but for those who appreciate convenience through continuity, I'll get them.
Here it is Copy-Pasted:
As simple as possible? #25
(M) While setting up my first course of dome bricks I wondered about the rationale for changing the plane of orientation for only that bottom course.
(M) I could not understand why that would be necessary since the 4.5" depth was a constant in every course ring, irrespective of the plane of orientation.
(M) I temporarily set up a few bricks with the "traditional" orientation of the first course on it's 2.5" edge, and 4.5" deep. That first image is a front
(M) The second picture will show a similar sized front view arc of a 42" circle but this time the first course is oriented the same as every other course in the dome, i.e., lying on one of it's two 4.5" sides and also being 4.5" deep.
(In that 2nd picture you will see one errant 1/2 brick purposely butted against the first 2 courses. It is there to show that 2 bricks of 2.5" are 1/2" (i.e. 5" height) taller than the "traditional" orientation of the first row which is only 4.5" height. I make this as a positive argument in favor of all bricks having the same orientation. The additional 1/2" will provide that much more height to the desired parabola profile and therefor provide more stability and resistance to horizontal pressures.)
(M) The third picture shows the back of the "traditional" orientation. Note that the support areas of the top of the first row are not equally distributed; some bricks have almost no support from the bricks left and right, and some are supported almost entirely by just one brick. I realize that mortar will fill those voids, but in terms of balance I suspect that a uniform orientation will help the Newbie consistently place his bricks in a staggered pattern with the distribution as uniform as the eye can make them.
(M) The fourth picture shows the back of the proposed new orientation. If you compare this fourth picture with picture #3 you will notice the even supports offered by a consistent orientation.
My arguments in favor of the new orientation are four-fold:
1- It simplifies instruction for the Newbie. S/he doesn't have to try to figure out what is meant by "side", "short", "long", etc. All that builder needs to know is that every brick lays on it's 4.5 by 4.5 side with the rough cut facing out for the mortar.
2- It is inherently more stable as there is almost twice the surface area on the hearth in that orientation as in the "traditional" orientation.
3- The added 1/2" (presupposes the same size circumference for the first two courses) works in favor of a higher parabola.
4- It is easier for an unskilled mason to see how to place the bricks when viewed from the back.
My argument against this arrangement is that the first course will not be as smooth a curve. That should not really matter as every subsequent course on even the "traditional" orientation will be a more "angular" curve.
(M) Einstien said that "Everything should be made as simple as possible; .... but no simpler!" Is this simpler than possible?
Marcel - I tend to agree with you and I questioned the placement of the first coarse as well. Although, when I laid this out on CAD, having the first coarse at 4.5 in. the bricks laid in there perfectly with a dome height of 21 in. James, can you please comment on this.
I think that this has to be the decision of the builder, and how you are comfortable getting shape you have laid out on your template on the ground. There isn't a way of saying one or the other is "right".
As a reference point, take a look at two professionally built Italian ovens:
The Artigiano, that we sell, has the first course upright:
My neighbor's oven in San Gimignano, which is made in Bari, has the first course flat:
My SWAG estimate is that a higher percentage have the first course upright, and all Naples ovens have a higher wall, followed by a steeper dome curve (Volta Bassa is the Italian name of our Casa oven -- low vault). Still, if it is easier and more secure to build the first course flat, and not pull your arch in too quickly with the second course, that works too.
Food for thought.
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