My first WFO build...

[Mooveebuff]

Hi Everybody! I have been reading on here for a long time, but finally registered today so I could post. This is a really big first post, so I apologize for all of the pictures. This has become more of a project than I thought it would be originally, although it's actually been easier than expected (so far!). All I can say is I'm glad I waited until the 100 degree-plus days were over before I started.

Reading all of the posts here have been very helpful, but I figured it would be even better to interact for a change and learn more as I go along here.

Anyhow, here's what I've done so far:

Well, things started off with what was probably one of the most difficult parts so far...digging a hole (a little over a foot deep)! I didn't get a picture of the actual hole, but here it is with about 5 inches of gravel to help with drainage for the rare occasion that it rains out here.




I covered the gravel with about 5 inches of concrete just to have a somewhat solid base. Just laying my bricks out here to make sure I made the slab big enough:




Put in some cinder blocks for support and started building the wall:

[Mooveebuff]

Re: My first WFO build...

Continued...




Filled in all the gaps with broken up concrete I got from a guy on Craigslist:




Covered the mess with concrete to get everything cemented in place and give myself a more level surface to work on:

[Mooveebuff]

Re: My first WFO build...

Continued...

Built the wall up a little higher to make room for my insulation layer:







Insulation layer - empty bottles set in a mixture of perlite and wood shavings:

[Mooveebuff]

Re: My first WFO build...

Continued...

I wasn't a big fan of working with the wood shavings and clay slip, so I switched to perlite and clay slip for the layer covering the bottles:







Evened off the top...just barely covering the bottles:

[Mooveebuff]

Re: My first WFO build...

And continued (last one, I promise!)

Filled the remainder of the base with a mixture of 3 parts sand to 1 part fire clay and set the firebricks in that slab to make my floor:










That's all I have so far. The bricks are set in place really well, but I just want to let the slab dry out a bit more before continuing. Next up is my brick arch and then building the dome. Getting close now! Thanks for looking!

[Les]

Re: My first WFO build...

Wow - interesting approach. Not sure what the bottles are going to buy you since solid glass is a poor insulator. Also, I believe it's recommended that the hearth brick can float. This will be fun to watch...

[shuboyje]

Re: My first WFO build...

If you are going to go to the effort of building up a brick dome I would HIGHLY recommend pulling up the floor and putting in better insulating layer. It looks like the hearth is pretty low right now anyway, so it would kill two birds with one stone. Insulation like you have are common in third world countries, and cob ovens muddled together from scrap, but if you are going to the effort to build an a brick dome, and you've already built a very permanent base, you want real insulation.

Sometimes posts like this aren't popular, they can come across as opinionated, snobbish, or even elitist. That's certainly not the motivation. Helping someone have an oven they are gonna love is the motivation.

[Mooveebuff]

Re: My first WFO build...

You're right, glass is a poor insulator. Air, however, is a great insulator. The purpose of the bottles is to create air pockets between the oven floor and the base. This is a techniques used to build cob ovens for years.

The base is just about waist-high. I don't want to go any higher, or it will make it too difficult for me to build the dome. I'm not building a brick dome...I'm making the dome out of clay. This will be more representative of "cob ovens muddled together from scrap".

The upside of doing it this way is that if I end up not being happy with it, the dome, floor, etc. will come apart easily enough and I can add on to the base and try again. This is my first go-round, so it's more of an experiment at this point. I learn better with hands-on, so I figured this would be a good way to go. Plus I didn't want to go to all the expense of that many bricks. This has been pretty inexpensive, just a lot of work.

Thanks for the input. I didn't take your post as being snobbish, and I appreciate your opinion. If I end up doing another one down the road or modifying this one, I may go the brick dome route.

[Mooveebuff]

Re: My first WFO build...

Well, I was going to go with a nice round brick arch, but discovered quickly that with my lack of knowledge and any real skill, I was going to have a problem getting it done....and I was worried about it holding up over time. Instead I went with this...stacked brick on either side, with steel bars running across the top with bricks set on top of those:





Beginning of sand form:


Sand form done....this took a LOT longer than I expected. Almost everything so far has!

[Mooveebuff]

Re: My first WFO build...





Covering with wet newspaper:

[Mooveebuff]

Re: My first WFO build...

Building the clay dome:

[Mooveebuff]

Re: My first WFO build...









If nothing else, at least I get to take a break for a while, which my back will greatly appreciate. Now all there is to do is wait...wait for it to dry, empty the sand, and fire it a little at a time to cure it. Then insulation and finishing plaster. Hopefully I'll have good news and more photos in a couple of weeks. Thanks for looking!

[david s]

Re: My first WFO build...

Because the clay will shrink, you need to remove the sand ASAP or the dome will crack because it has no room to move. It will take a long time to dry.Normally pottery needs a week to dry before firing, your walls are many times thicker, so will need way longer.Did you use any straw or sand in the mix?

[Mooveebuff]

Re: My first WFO build...

I was hoping to let it dry for a few days just to ensure it will hold its shape before removing the sand and letting it dry completely...is that still going to cause me problems? I expect some cracks, I'm just hoping to avoid it splitting in half. Of course, it rains like 3 times a year here and it just has to be cloudy and raining since I finished the dome! Two good sunny days in a row and I imagine I could clear the sand out.

The mixture is actually more sand than clay, although it looks like it's mostly clay. It's Muddox fire clay mixed with 3 parts sand (fine, medium, and coarse). I did not use any straw with this attempt.

[david s]

Re: My first WFO build...

The sand in the mix will reduce the shrinkage, but it will also reduce the drying rate. As soon as it begins to dry and the surface feels firm it will be shrinking. It won't collapse because of its form. Get the sand out ASAP. If it were mine I'd be leaving it three weeks before thinking about any fires.