Insulation | Part 2

I fitted the insulation this morning. Took about an hour. The piece of rockwool I got was just a bit too small (should have got 3 square metres) so I had to scrounge a bit of roof insulation from a skip bin on a building site. I've checked the specs on-line and I'm confident it will stand up to the heat.

I draped the insulation over, cut out a few triangle sections to make it fit the dome, then used tie wire to 'suture' the joins.

I've covered the insulation in chicken wire, to give the external coats of render something to hang onto. The method for this is exactly the same as for the fitting of the insulation. I used scrounged chicken wire, but ran out and had to buy a bit more. This was finer wire (13mm mesh/0.56mm wire) and was much easier to work with.

At the door, I've folded the wire back around the insulation, then joined the two sides with a couple of lengths of tie wire. It doesn't matter about the edges of the insulation around the door as this will be covered up by the walls of the smoke chamber. This will be added after the dome has been rendered.

A bit of Cosmetic Work

Today my dad gave me a bit of a hand to start building a retaining wall at the back of the oven. This will become a herb garden where I can grow basil for my margherita pizzas.

I used the left over mortar to tidy up the outside of the dome. Because I'm not that fussy about how I split the bricks when making the dome, there was a few divots that needed filling up. There was also one small gap in the dome that I noticed smoke escaping from when I fired the oven up again last night. A screed of mortar has fixed that up. Now I've got a reasonably smooth dome ready for the insulation to be laid over.

I've learnt abit about applying (and removing!) make up as part of my work this year. I recon today's job on the dome is probably like applying a layer of foundation. Get this layer right and the finish should be fine.

Insulation

Managed to track down some insulation today. Big thanks to Gary at Right Homes for helping me out with this. Gary and Anna built my house. Great builders, and also just beaut people. Even six months after the build has finished, Gary was still keen to help me out.

Gary recommended that I use rockwool insulation in the wall cavity of the house as a way of maximising the effectiveness of its passive solar design elements.

This product is also spot on for insulating the oven. It's made from a mixture of rock and recycled building material. It's non-combustible and will withstand temps up to 650 degrees.

First Firing

Ducked home tonight and whipped out the mold. Dome looks good!

Scraped what sand I could off the roof of the dome and then cleaned up the floor. That did mean squeezing my top half into the oven to scrape the floor with a trowel.

Then it was time to light the first fire. Modest admittedly. Four sheets of newspaper...but the first fire none the less.

Timing

This is the third weekend that I have worked on this oven. The days have been pretty casual, still allowing for a sleep-in and lazy breaky whilst reading the paper.

On the first weekend I built the metal base frame and set it in place.

On the second weekend I finished off the base by laying the cement fibre sheeting and a layer of pavers.

During the week I did a few little jobs in the evenings to make sure that everything was ready to get the dome built this weekend

This weekend I whacked up the dome. It prob only took about 6 hours of actual time on the job.

Next week I'll have a bit more time on my hands. My plan is to have the oven finished by the end of next week. That will mean:

• Covering the dome in insulation, chicken wire and render
• Building the smoke chamber and installing a chimney
• Laying some slate around the outside of the dome.

We'll see how it goes!

Some thoughts on the Dome

As you can see, at this point things aren't looking very pretty.

I've used up left over mortar to start a render coat on the outside. I don't really think that this is necessary, as there is still a layer of insulation to go on prior to the finishing coat of render being applied.

A coat of render at this stage though,will

• use up left over mortar
• seal up any gaps between the bricks
• even out the dips and hollows of the bricks to provide a consistent thermal mass layer.

Sunday evening. The dome has been laid in a weekend, the dome mold is still in place to allow the mortar to set the bricks in place (I'll prob pull it out tomorrow night), and the sight has been cleaned up.

My back is aching, my hands are stinging and my hamstrings are feeling pretty tight from bending over all weekend. I'm feeling pretty content that I've created something useful and got some exercise at the same time!

Building the Dome | Part 3

Once the dome mold is set up, it's just a matter of setting the rest of the bricks in place. I kept going in concentric circles, setting each brick in place as I went.


When I got to the last few bricks, I had to knock a few edges off them to make them into wedge shapes so that they would lock together to support the dome. Then it was just a matter of getting as much mud in between them as I could to fill up the gaps.

I'll leave the mold in place overnight to allow the mortar to set the bricks nice and firmly in place.