Monday, 12 November 2007
Saturday, 27 October 2007
The blocks suck up water like a sponge, so I'll need to get a cover over this pretty soon. Next comes the fun part - building the oven.
Saturday, 13 October 2007
The poured hearth slab will end up being about 5" deep in the middle (over the three block piers, and tied to them with the bent rebar), and at the 6" near the edge it will slope up to the edge of the form where there's still space for about 2" of pour.
Sunday, 16 September 2007
I felt I should do some real work too, so I mixed three barrows of concrete, bent up some rebar into right angles, and filled the cores of my support blocks, using a couple of bars in each.It all looks pretty ugly inside at the moment. The rebar will tie the cores to the hearth slab, which will be the next thing to be poured. First I need to figure out the best way to hold the concrete in over those very uneven stones.
Saturday, 8 September 2007
That's one of the blocks in the background, which got the hot end of my blowtorch for ten minutes. The spot I heated glowed red after a few minutes, then a satisfying yellow colour after ten minutes. I turned off the blowtorch after ten minutes and started my highly scientific test. The block was still cold on the back, so I tested to see how close I could put my thumb to the spot that I'd heated without screaming in pain. Told you this was scientific.
I could hold my thumb comfortably at about 4cm from the spot that was glowing yellow - this was about twenty seconds after I'd stopped the blow torch. The block was paler where it had been heated, although still pretty tough. I scraped a hole in the block, and the discolouration was only for the first mm or so.
I think these look promising - as insulation they'll never need to take this sort of direct heat, so my test was way over the top. They're clearly good insulators - I think I'll use these under the heath. I'm impressed that they're a recycled product themselves, which fits nicely into the ethos of my oven build.
The fire burned for about 3 hours (a lot of stuff to get rid of), then burned down overnight. The embers were still red and glowing after 6 hours, so those bricks got pretty hot. 24h later they were still too hot too touch, and were almost too hot to hold with my thick welding gloves on. The bricks survived fine - didn't seem any worse for wear after their cooking. That's a cooked one on the left - the one on the right is uncooked. I think they'll be fine for my doorway arch - the chopped off bit should allow the inner door to fit nice and tightly. And they're free!
Sunday, 2 September 2007
I had some help from a very enthusiastic three year old with the last few lumps of rubble (thanks Thomas!), but still had a fair bit left. No matter, simply bung it in the spaces around the concrete support pillars - I can use it to help support the hearth when I pour it.
I'll fill the last foot or so with more rubble once the mortar's set on the top stones. I'm pretty pleased with that for a first effort - the uneven levels on the walls will be taken care of when I pour the (level!) hearth. If anyone else asks me how I'm going to get the pizzas to fit in that little brick hole, I'm going to hit them.
Tuesday, 28 August 2007
The slab is there to help judge the height - the oven front will be inside the summer house, which will have a pebble mosaic floor, so the floor will be about 2-3" higher than the slab. I'm stopping for a rest now - hopefully I'll get some more done next weekend.
Monday, 27 August 2007
You can see I've added a triangle of concrete blocks in the middle for support. I plan to fill the gaps in these (and the triangular gap in the middle) with poured concrete, and insert bent rebar into them to tie these columns into the hearth slab. This should provide all the support the slab needs - leaving my outer walls only supporting a small fraction of the weight. The hearth slab will be reinforced as well - I feel sorry for anyone who tries to demolish this future...
Saturday, 25 August 2007
This is slow work, and it's fiddly trying to get stones to fit in gaps. I'll probably fill the spare space in the base with rubble and subsoil from elsewhere in the garden. I'm saving doubly here - to get rid of all this concrete and subsoil I'd need to hire a skip, and the cheapest you can get a decent sized one for round here is £130!
Friday, 24 August 2007
Here's the slab, all marked out ready to go. I'm only building within the big circle, so my maximum diameter will be 1550 mm. Hope that's enough space - we'll see.
Thursday, 23 August 2007
The picture here shows the site, taken in May 2005. My plan is to have half the oven enclosed in the summer house, which will be set at a 45 degree angle in this corner. The bit behind the fence has my polytunnel and veggie garden - must remember to get a decent spark arrester for the chimney to save melting holes in the plastic... The plants up the fence are siberian kiwis - they've already started to cover that ugly fence pretty quickly.