Clay Oven on Verandah

[BackyardPermaculture]

Re: Clay Oven on Verandah

Thanks for the tip David - I'll be especially careful with the drying.

I got the sand out of there the following morning, and put 2 x 200 watt halogens in there for 24 hours - lots of steam was coming off overnight and it's much drier now. But I'm planning on progressing to some heatbead fires.

Also planning to insulate with thick layer of rockwool and then vermicrete, so the dome should have freedom to move.

Cheers,
Mick

[david s]

Re: Clay Oven on Verandah

Mick,
With the high percentage of unfired clay in your mix you will get a lot of shrinkage which means cracking unless the dome can shrink. You should remove the sand in the middle as soon as the dome is self-supporting , which is probably straight away. Some lime in the mix would probably have helped make a stronger and more refractory brew, but I'm sure what you have done will work, but take a long time to let it dry before you cover it with anything else. The clay in the middle will take ages to dry although the outside may appear dry. Ask any potter who has to fire thick sculptural work. We're talking weeks.

[factoryrat]

Re: Clay Oven on Verandah

250 kgs = 550 lbs

[BackyardPermaculture]

Clay Dome Formed

We formed up the clay dome on Saturday:

- Formed up the archway with an MDF tunnel and lots of foam boxes and sand to form the dome.
- 1:1:1 dry mix of ball clay, brickies sand, crusher dust. Added quite a bit of natural rope fibers, small amount of Portland cement. Didn't make it wet enough for first layer, but the second and third were good.
- Used less clay than expected; only used 1 bag (25kg).
- Removed the flue pipe for now, just so I can keep a tarp over it - rain expected this week.

Very happy with the results - so far it's taken 4 weekends to get to here.

[david s]

Re: Clay Oven on Verandah

It is all a matter of how much weight is going to be on your deck. My oven is 250 Kgs because it is small and therefore ok to put on a deck. You guys are thinking that all ovens weigh tons.250 kgs would be the equivalent of four big guys standing together on the deck having a quiet drink.

[BackyardPermaculture]

Tiling Complete

I got the tiling finished - these are the free charcoal-coloured glazed porcelain tiles that were left in our shed. The "French Vanilla" grout goes well with them - not finished cleaning them up yet.

Also mortared the row of pavers and grouted the hearth pavers with fire mortar. The 1kg (2 lb) tub was just enough to do the whole lot.

Next weekend we begin on the dome - will be mixing clay, sand and crusher dust and forming it over a sand mound which will be removed through the door opening afterwards.

Cheers,
Mick

[Archena]

Re: Clay Oven on Verandah

Hmm, just a thought but you might want to seal the deck if it's due before you start the oven. That will protect the underneath until enclosed and hopefully keep you from enclosing wet boards - which would be a very bad thing.

Then again, I imagine that depends on the climate in Brisbane - if it's dry there shouldn't be a problem. Here in Alabama there's no such thing as a 'dry' day - high humidity, anyone?

[BackyardPermaculture]

Re: Clay Oven on Verandah

Decks are not built to the same loading standard as inside floors and the connections are exposed to the weather and thus deteriorate with time.

That's probably my biggest concern with it, actually.

[BackyardPermaculture]

Re: Clay Oven on Verandah

Lots of scary pictures

You got that right!

But in this case, I'm increasingly confident it's OK based on the structure of the deck and the forecast weight of the oven.

The weight of the oven should not be more than the weight of 4 or 5 adults. My oven will be a slightly-larger version of this one (but with the chimney OUTSIDE the door); the dome will contain less than 150kg (300 lbs) of clay/sand, and I estimate a total weight of 350kg.

The thing about all of the decks in those pictures is they were attached to the back of the house. My deck isn't at all like that - the joists come right through from the house, and the back wall of the house sits on the same joists. I really can't see that 350kg of oven should be a concern on there.

Cheers,
Mick

[Neil2]

Re: Clay Oven on Verandah

"It seems that people are killed every year in deck failures."

Decks are not built to the same loading standard as inside floors and the connections are exposed to the weather and thus deteriorate with time. Worst still, many decks are built by homeowners with no building permit, therefore no inspection, therefore an accident (and lawsuit) waiting to happen.

[Neil2]

Re: Clay Oven on Verandah

"The safe method is to build from proper footings on the ground next to the deck. I know it's a lot of masonry, but haven't you always wanted a brick garden shed?"

And you will still have the use of that part of the deck that would be taken up by the oven.

[dmun]

Re: Clay Oven on Verandah

I have to agree. One of the links in Neil's suggested search is:

http://www.mosbybuildingarts.com/blo...deck-collapse/

Lots of scary pictures. It seems that people are killed every year in deck failures.

The safe method is to build from proper footings on the ground next to the deck. I know it's a lot of masonry, but haven't you always wanted a brick garden shed?

[Neil2]

Re: Clay Oven on Verandah

Don't build an oven on your deck.

Do a google search on "deck collapse".

[BackyardPermaculture]

Re: Clay Oven on Verandah

Something I'm not too keen on being the first to do!

[Archena]

Re: Clay Oven on Verandah

Our state had a holiday today so I was able to cut all the tiles and the few bricks that needed cutting. The tiles are really nice - someone left them in a shed when we bought our last house; not enough of them to use for a regular project but plenty for an oven!

Cool! My favorite kind of supplies - free!

I've checked out a few more things, and concluded the following:

- The deck-to-house connection is fine; the joists sit on the same bearer as the back wall of the house.
- Decided to sacrifice most of the landing area at the front, and move the whole dome forward on the base. Then I can move the base back towards the end of the deck.

- Also reduced the width of the oven by one brick; brings it to the size of the original plans, about 30 x 26 inches. I did this to leave plenty of room all round for lots and lots of insulation - just so I don't set the house on fire

Cheers,
Mick

Awww, come on - no one's burned down a house around here. Don'tcha wanna be the first?