Clay Oven on Verandah

[simonoz]

Hi Mick,

A couple of pictures of my Clay oven build.

[BackyardPermaculture]

Simon,

That looks really good! I like the paving you've got around the edges.

The more I look into rendering the clay, the more clear it seems that it's a bad idea to render it waterproof. Moisture needs to transpire through the clay and out through the render - which is why cob and adobe/mudbrick are usually rendered with lime renders and the like.

I've chosen to enclose mine in a steel-framed fibrous cement sheeting enclosure, which will be coated in a render paint from these guys:
http://www.appliedcoatingsystems.com.au/

I have the paint but haven't applied it yet - just finishing tiling around the top first. It's quite precarious trying to work on an oven on an upstairs deck!

Cheers, Mick

[simonoz]

Hi Mick,

Attached couple more photos during the build, note that the render is only applied after the vermiculite layers. The render I have used is a lime based render and I have used a Bondcrete additive in the render.

The cracks I have in the render I think is a result of using the bondcrete and not having sufficient thickness (6mm). Plan to reapply over current render without the bondcrete and additional lime ratio using thickness of approx 15mm.

Simon

[BackyardPermaculture]

Hi Simon,

I've not actually applied that kind of render before, but it sounds like it may be too thin. I actually owned a mudbrick house for a few years, and it had been rendered with a lime-based render with bondcrete added. That was a really nice surface (well protected from rain by a wide verandah) but since I didn't apply it I don't know too much about specific thicknesses etc.

Someone around this forum is bound to know something though...

Cheers,
Mick

[BackyardPermaculture]

Finally cooking

I've been running some fairly hot and long fires, and cooking chicken etc., but tonight was finally the night for pizza!

The top-down fire worked really well, except that in the middle tier I had some framing timber offcuts (untreated pine) that smoked like crazy.

I used Peter Reinhart's recipe for pizza dough; found the resulting dough a bit tricky to handle but it puffed up really well and tasted great. I burnt the edges on one side - need to get a turning peel at some point.

Cheers,
Mick

[Archena]

Oooh! Nice! Congrats on the pizza!


I read a website of a builder who does cob houses professionally and he was adamant that using concrete was an extremely bad idea. It doesn't allow evaporation fast enough and can cause water damage and eventual failure. I don't know if bondcrete overcomes that limitation or not but I wouldn't experiment with anything I cared that much about.

When I (finally) buy a place I plan on doing my doghouses in cob - I might try that with a doghouse as an experiment since it wouldn't bother me to have to rebuild it.

I can get you that link this afternoon if you like. I'm about to run the dog to the vet (this should be the end of 8 weeks of doggie bed rest during heart worm treatment - yay!) right now.

Oh, I did have a quick question, BP - did you use joist hangers in your base?

Later!

[BackyardPermaculture]

A cob dog house? Wow!

We found the adobe house we lived in to be "difficult" in the climate here, which is basically subtropical. The house was on the outskirts of the city, where it also gets frosts and cold nights (as in down near freezing, but not below freezing) in the winter. It was a huge (I mean it - huge) adobe house (12,000 bricks each weighing 15kg) and when it cooled down it took three days to heat back up running the fireplace at night. And when it got hot it was hot all night - like a hot summer day radiating out of the walls all night.

We installed a passive cooling system that vented out through the ceiling with venturi things on the roof - that improved things. However possums started falling through the vents. At 3AM it's not much fun to have a live possum drop 8 feet onto your bedroom floor; they are quite difficult to get out of the house. The happened about 5 times in various rooms before I had to start putting screws through the vents into the ceiling.

Oh, I did have a quick question, BP - did you use joist hangers in your base?

I didn't use joist hangers - I ran long screws through the timber (the kind of screws I've seen them use here on outdoor stairs etc.) and a large galv coach bolt on each leg as well. Would have made the base smaller if I knew I was locating on deck - should have reduced its size when I moved it up there.

[Archena]

Falling... possums...

Um, yeah... EEK!


Thanks for the info on the joists.

[BackyardPermaculture]

Well, I'm basically finished - only thing outstanding is a bead of silicone where the enclosure walls meet the tiling on the base. A bit of a scary job actually, since there's no room to work around the edge of the deck.

I painted the chimney with the same coating as used on the enclosure - it's got a really nice texture to it and doesn't look likes it's made from galvanized iron any more.

The roof is almost flat, with a slight slope towards the back. I tiled the roof with large (18") off-white tiles that were free leftovers.

Really happy with this oven, given the relative low cost, light weight, and speed of build.

Cheers,
Mick

[Archena]

Beautiful! Nice job!