Paul's Canberra build

[brung99]

Re: Paul's Canberra build

Hi Paul,

Congratulation on your new arrivals, they are beautiful babies. They will be the most important "project" of your life, so God bless you on your family's journey.

Thanks for the updated photo's - it looks to be coming along nicely. I havent started my build yet, but i have bought my bricks in preparation. I also found some 2nd hand kiln bricks (on Ebay - Newbold brand) which although a bit "rustic", I couldnt knock them back for the price. I Really cant wait to start.

Keep the updates coming !!.

Regards,
Bruno.

[Mahootna]

Re: Paul's Canberra build

and so on it continued.

The first couple of courses went fairly smoothly. Whilst the angle remained low, it was easy to lay an entire ring every day or so. But, once the angles got steeper, it was more like a couple of bricks each day. I didn't use any of the specialist brackets used by others around here. I just stacked up a bunch of bricks inside the dome for the newly laid bricks to rest against. I also found I had to cut little wedges to fit in the gaps between the bricks as the circles got smaller and the gaps bigger. I cut a couple of custom bricks for the keystone(s).

Dome complete on 1 January 2011

I had intended providing a blow by blow description of the dome construction because I found I learnt a lot during the construction. I'm sure most others have found this as well. In a way it's a pity these things are so solid. If you've never worked with bricks and mortar before, the learning curve can be quite steep. The theory is all fine - it's the actual working with the material where the real learning takes place - getting to know how the mortar feels and works, seeing how the bricks stick (or don't), not to mention the myriad of ways you wish you'd changed your design the moment after the concrete set.

[Mahootna]

Re: Paul's Canberra build

First fires. mmmm pretty

[Mahootna]

Re: Paul's Canberra build

I pretty much followed the standard curing fire regime - start small and build up with thicker pieces of wood, longer and hotter burn times.

It was pretty nerve wracking getting that first super hot fire going. I still didn't have any insulation on, so I was able to watch in horror as the cracks opened up. At one stage I had a crack right up the back that got wider as the dome got hotter. At its peak I could see flames through the crack. I thought the whole thing was just gonna collapse in on itself, showering the backyard with hot coals and dust. Thankfully that never eventuated. I let the oven cool down and the crack closed up. I reheated several times, and the crack seemed to calm down. It always grew as the oven heated up, but never to the extent of the first occasion.

Incidentally, that first big fire was the perfect occasion to throw in some vegies for a roast lunch.

[Mahootna]

Re: Paul's Canberra build

In those previous photos, you can see the entry and outer arch built. This was another area I wasn't sure about. The arch itself wasn't too difficult. I cut the bricks using a standard 125mm (5") hand-held angle grinder with with masonry blade attached. The bricks cut like butter, so it was simple to work out the angles I needed and slice off the bits I didn't want.

I wasn't sure what to do about the supporting walls in the entryway. I was paranoid of a collapse. Anyway, I got a bit distracted with the arch and was so pleased with the way it looked, I went ahead and cemented them in place ... only to realise the bricks in the supporting walls were just sitting there ... no cement, nothing holding them in place ... whoops.

So, i got the idea to put some brackets in to stop any outwards movement. You can see the metal bracks - essentially two inverted U-shapes bolted together. I have them held in place using a heat proof adhesive. I don't expect the adhesive to stand up to the heat it will likely be subjected to, so to boost the holding power, I have wire running over the arch holding the two bracket pieces together. The whole lot will be further supported by the thick render layer I'm going to cover the lot with.

Here's a close up of the left hand bracket. It's just the three vertical bricks that make up the entry wall. The other brick is just sitting there.

[Mahootna]

Re: Paul's Canberra build

Next step, insulation. I found working with the insulating blanket quite easy. As many have said before, it's easy to cut, and it tends to stay in place where you put it. It was harder getting the wire mesh to do the same. It'll do what it wants until you wire and bend it into submission.

To cover up the insulation, I used a good thick layer of standard render. I used by hands a fair bit to massage the render into the wire mesh, get it to stick and smooth it to the shape I wanted.

For anyone who hasn't worked with concrete before, lime burns really do hurt. Early on I had stuck my bare hands into wet cement to mix and so on. You don't realise it's burning. Any small cuts or scrapes are worst - they pick bits of cement and it sets, burning further in. The next day you'll feel it. Had to take a day off work coz I couldn't button a shirt alone drive a mouse or keyboard (yeah, I'm a desk jockey). So, whilst using you hands is a good way to mould the render into the shape you want, use rubber gloves. And, the gloves will wear through quite quickly. Change them.

Anyhoo, here's some photos for your viewing pleasure.

[Mahootna]

Re: Paul's Canberra build

... and render going on ...

Here you can see that I have covered the dome, placed the flue and covered the top and sides of the entry arch. At this stage I have not touched the base surrounding the dome nor the front face of the arch. I did have aspirations of covering these parts with some tile, brick or stone covering. I shopped around and could never really find what I wanted. Actually, I did find some really nice black limestone that would have looked pretty good, but at a squillion dollars per cubic centimetre, and being almost impossible to cut into a curve, I quickly changed my mind.

In these photos I still had no idea how I was going to finish it off.

[Mahootna]

Re: Paul's Canberra build

Then I thought "that render was pretty easy to work with, so why not finish the lot off with render?"

I whipped up a wooden frame for formwork for an outer entry arch and wedged it into place. I then attached some more mesh into place for the render to stick to. The outer arch has a lip at the top to divert more of the smoke up the flue rather than out the front.

I gotta say, I was pretty chuffed with the outcome.

[Mahootna]

Re: Paul's Canberra build

Now, shield your eyes ... don sunglasses ... and put on a hat

Covering the render was another dilemma. I first thought I could use some waterproof render coat that could take some heat and expand/contract. After doing some hunting around, I came to the conclusion that no such product existed. I dunno what others have used, but once I explained what I needed to a guy at a specialist paint store, he suggested I just use paint. It wasn't structural, so didn't need to be thick. It just needed to be waterproof and somewhat flexible.

Because I wanted the sandstone look, I went for a textured paint product. I didn't have to do that, because the render already had the sandstone feel, but the textured paint went on thicker than a standard paint would, providing extra flexibility.

As for colour ... hmmmm. How do I describe it. Bright? Perhaps. At one point the space shuttle tried to land in my backyard. Low flying aircraft have complained about blinding lights. And bees ... bees have tried to mate with it.

Ok, so the colour is a little brighter than I expected. You really don't get a proper idea of a colour from those silly little swatches they make. I thought it'd be a little more sandstoney than bumblebee, but bumblebee we got. I even thought about painting black stripes around the dome to complete the look.

[Mahootna]

Re: Paul's Canberra build

In the next instalment, I shall take you through making the bench top ... oh and show you how thankfully the dome has toned down somewhat. It has faded into a more respectable pale yellow with a nice black smokey mouth indicating plenty of use.

[david s]

Re: Paul's Canberra build

If you glue some glossy tiles around the front of your arch any smoke staining will easily wipe off with some damp newspaper.Use a black grout.