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Dry Stacked WFO V1.0 Drawings & Specs

01.06.11

I know from experience that any specifics on building wood ovens and grills is appreciated by those collecting ideas for their own build, so upon requests in the comments of previous posts about it, I’m providing drawings and additional information here for those that have  requested it. I’ll just keep adding to it as requests come in.

Total Cost: ~$30 + gas to haul the mostly free masonry. Not including my time, of course.

Total Time: 3 hours. From having piles of masonry around the yard to having a fire in the oven, including grill build.

A few key points.

First, the oven entrance is 3 bricks tall, while the oven top is 5, providing very close to the optimal ratio of door height to ‘dome’ height. That ratio was common regardless of which camp the builder fell into. “Yes, 63% is an imperative. Actually it can vary a little, maybe 60 – 65%, but that is what optimizes the exit gases to heat retention. You don’t want 100% because all your heat will go out the flue. Too small of an opening will not allow the combustion gases to flow properly. 63% is optimum.” – lwood @ fornobravo forum.

Second, this build is made possible by the pavers which are roughly 1′x2′x2″ – providing the ability to span the oven walls. Normally ovens are domed, which is better for both heat reflection and strength properties. To achieve a flat structure with some strength, all the pavers that span the oven roof are on edge, not on flat. I’m no engineer, but I figure it’d be far harder to break a paver on edge, and it can likely hold vastly more weight as well. It also provides a foot of thermal mass atop the oven, albeit unsealed between them. Conveniently, the paver roof of the entrance, if built flush with the adjacent bricks, provides for another paver to fit perfectly as a door. Works great.

Lastly, improvisation required. Your building materials may be different than mine or you may have a better idea on how to tackle it – and you’ll need to adapt accordingly.

Various photos of this particular setup will be available here. More to come if need be.

10 Responses

  1. Incredible. Love the specifics. Now, I DO see that the print on this site is your own… someday I will corner you and ask how you did that for your main font on this site… but, for now – my thoughts are your interface offered you this option… yet, your platform is wordpress… anyway. Don’t answer, unless it is a short answer. I just love that it enables such a personal touch.
    :)
    Valerie

  2. Valerie – short answer: they’re all scans of my handwriting, made the backgrounds transparent in photoshop, and imported them into the various graphic elements of the theme. They’re not fonts. Just a graphic design choice, for precisely the reason you mentioned.

  3. Mike says:

    Excellent, the nice thing about your setup is that it could be moved, repaired, or re-designed as necessary.

  4. Mike – that is a serious perk to the setup, no question.

  5. Chris says:

    Love the details Kevin! Thanks again for taking the time to post this up. Can’t wait for the snowy weather to break so I can get my space leveled off and setup. Got an old stainless steel ice machine that I’m converting into a smoker to add to the mix now too. Craigslist and Freecycle etc…. are your friend for these builds!

  6. Greg says:

    Valerie – have a look at http://cufon.shoqolate.com/generate/ or http://typekit.com/

    One piece I kept wishing I had when building a rocket stove (which this could be called) is a metal plate that would form the top-front of the ‘door’, which would then heat up and could act as a griddle. It could be made large enough to be useful. Perhaps if it extended into the chimney a bit, and just above that in the chimney were another such plate only there to force the hot air back over the top of that plate, too, then it would transmit even more heat into the metal. Sizzle!

  7. Kevin says:

    Chris – look forward to hearing more about your setup, and it’s always exciting to hear of folks using re-purposed ‘stuff’ from the waste stream to make functional cookery gear. LOVE it.

    Greg – nice griddle idea. If I took the top bricks off my oven, and put a steel plate on it, you could feasibly use that once it was good and hot? Right now, it’s hot enough to dry gloves on, so you’d have to remove some thermal mass. It also is a bigger area than the front lintel, and more exposed to direct heat. Just another idea for the collective. ;)

  8. Greg says:

    Yeah, I got the water bath canner boiling at the top of our little rocket stove ‘chimney’ one time. (The inevitable soot wipes off afterward.) Definitely a hot spot in the works. Also pondering porting over the lessons I’ve learned about restricting air flow to the fire-cum-embers in order to let it pitch off heat rather than burn away more quickly in the draft. And ideas for temporary mortar, perhaps wet sand or dirt? to cinch off air gaps in the otherwise dry-stacked bricks. Collective thought indeed!

  9. Kevin says:

    Greg – I used foil atop the pavers to prevent airflow out that direction. I’ve seen guys use it on permanent oven builds as well. Mine leaks a fair bit out the oven bricks when the fire’s at its max, but once it’s a mature fire the chimney pulls the vast majority of smoke and gases out the chimney, believe it or not. At least it looks that way. Temp mortar though…not sure. Mine has very obvious holes that blacken with soot – one could take some mortar and plug the obvious gaps I suppose. I’m not going to as I’ll be doing a mortared version soon enough. You’ve got me thinking though….

  10. [...] want an outdoor oven like Kevin Kossowan’s.  I’d love to have an oven like this to use while entertaining [...]

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