Oven#2 - this time its modular

[nixie]

Back after a long time off the forum (I've been reading but haven't posted since our last oven was left at our old house). After lots of negotiation a new oven was approved, though despite having a nice pile of bricks for a Pompeii build we compromised on me building the base and buying a kit oven (wife worried about the smell which came from smouldering insulation on the first oven). We now have a stone baked oven Mezzo sat in a crate in the garage waiting for a base. I've made good progress and am hoping to get the oven finished before the winter is really here.

I'm working roughly from the plans listed on the stone baked site with adjustments to fit the space available (oven cannot go any further to the right as our bi-fold doors open right next to it). I alos decided to go for and arch instead of the lintel for the wood store entrance. This is a copy of the design used on the house windows.

Cutting a hole in the decking (this area was a bit rotten).

IMG_20150830_172614954 by nixie_me, on Flickr

Cleaned up with shuttering in place.

IMG_20150906_144919721 by nixie_me, on Flickr

Ready to pour

IMG_20150907_141811083 by nixie_me, on Flickr

Half way

IMG_20150907_151723872 by nixie_me, on Flickr

Done and set (including 2015 dated coin)

IMG_20150911_132933907 by nixie_me, on Flickr

Start of bricks and blocks

IMG_20150911_183146453 by nixie_me, on Flickr

Going well

IMG_20150920_181710809 by nixie_me, on Flickr

Wood store arch

IMG_20151015_152737214_HDR by nixie_me, on Flickr

Finished the bricks

IMG_20151019_084410521 by nixie_me, on Flickr

[nixie]

As you can see the first 2 brick courses where a smaller size. This should be hidden once complete though.

Next up is the oven slab. I'm hoping to get this poured this weekend but currently have a dilemma. The plans (https://www.thestonebakeovencompany.co.uk/wp/wp-content/uploads/Mezzo-76-Render-Manual.pdf) show the bricks coming to full courses above the blocks. A 12mm board is placed on the blocks and then concrete poured on top. My bricks don't protrude by 2 full courses, I've got 11cm between the top of the blocks and top of the bricks. What I can't work out is if this is going to make the slab thick enough or if it really needs to be thicker. Anyone got any thoughts?

[purrcat]

In building mine I decided that I didn't need the full depth of the base for storage and put a dummy wall about half way back - have a look here

ukwoodfiredovenforum.proboards.com/thread/2293/modular-oven-surrey

You could use a dummy wall to provide central support.

Or/and you could add lintels mid way back and at the front to add more support.

My base is about 6 inches thick and 12mm of that is marine ply. To be honest, if you follow the mix instructions (I used 5:1) and really float it well and with plenty of rebar in the core I think you will be fine - but I would add that central support in the middle though.

[nixie]

I had a good read of your thread yesterday. Looks like a nice oven you've built there.

I'm trying to avoid the central wall if at all possible. We really need as much wood storage space as possible as we don't have the room for other wood stacks really. I had though about getting an acroprop an placing it permanently in the centre.

On the good news front I spoke yesterday with the technical department at Stone baked oven and they indicated the 110mm I've got will be enough. Just need to use removable shuttering instead of left in place cement board. Fortunately I've got some old fire doors in the garage and there is a wood recycling project 2 minutes from my office (cheap scaffold board offcuts).

[kstronach]

110mm of concrete in my opinion will be fine with reinforcing in, you wont need to leave an acro in there. whats wrong with the leave in place concrete board? once its set with the reinforcing in, making sure the rebars go over the walls you're casting on to, the board won't e doing anything anyway, i can't see what harm it will do!

keith

[nixie]

Nothing wrong with the leave in place board apart from the fact it will take up some (approx 12mm) of the available depth. If the base wasn't already so high I'd add 1 more course of bricks and use it but I think that will make the oven too high up.

[nixie]

Good progress this weekend. Hearth slab now done.

Woodwork to support. 4 3"x2" posts in the corners with the same on top of each to make platforms for the top boards. Thin bits of cross bracing to hold posts in. Thin shims under each to aid removal. The stack of old thermolights in the middle is for extra support and to make removal easier (will move posts first then central stack).

IMG_20151025_112939578 by nixie_me, on Flickr

Old scaffold boards cut to fit the gap (Rip cut in scaffold board by hand not fun). These are set 2cm below top of blocks to compensate for thickness. Probably unnecessary but makes me feel better.

IMG_20151025_112947019 by nixie_me, on Flickr

Plastic membrane to seal the gaps. I might cut this out afterwards depending on how it looks from below. The bit of rebar fit really nicely in the the width, hardly had to cut it at all .

IMG_20151025_133955846 by nixie_me, on Flickr

And done. Bit of wood on the right is to compensate for the right hand wall being a bit lower. I will level the wall/slab interface using the mortar for the decorative finish.

IMG_20151025_155805960 by nixie_me, on Flickr

The former wood is going to be reused as a false floor for the wood store. Mid week I'm going to take the former out and then hopefully next Saturday the oven will be lifted into place.

[kstronach]

good job! what are you using for insulation under the oven?

[nixie]

Thanks. The kit came with some calcium silicate board so will be using that.

[nixie]

Got the oven in this weekend despite a over tired threenager and house full of colds. It was hard work though and everyone ended up with trapped fingers at some point!

I decided to wrap the calcium silicate boards in tin foil to attempt to keep moisture out. I was very glad of this after the first placing of the base pieces as we had to space the rear piece using sand to get the cooking and contact surfaces level. There is still a bit of a lip over the join however I will sand this out. The main part of the dome was really hard work to position, could have done with more space around the base so to allow more flexibility in holding on to it.

IMG_20151101_165555596 by nixie_me, on Flickr

[purrcat]

That really is probably the most worrying bit completed. The modular ovens offer some distinct advantages in that the build is rapid. However, people under estimate the work involved in positioning them. It's one thing lifting a heavy weight a few inches off the ground but quite another lifting it up by several feet.

Wrapping in tin foil is definitely a good move as these boards are a problem if they get wet.

If you have an archway you may want to consider doing what I did: I separated the arch from the dome by about half an inch and attached it via a few brick ties to the dome. That way the arch wont act as a heat sink and take away precious heat from the dome. I have inserted open door rope in the cavity so as to plug the gap.

Nice brickwork by the way!

[nixie]

The fine adjustments are also not so easy! The force level required to shift it makes it very, very easy to over shoot!

The kit came with an archway however I don't like it that much (it gets rendered over apart from the outward facing edge, I prefer the brick look). I still have some bricks left (though they need a fair bit of cleaning) and also quite a few half bricks. I thinking of making an arch roughly the same size as the kit arch with a single 'layer' of half bricks, then using full bricks to form a second layer with these being offset either a quarter or half bricks depth from the first layer. This should give a nice entry I think and link in with the base. This would also provide a location for a secondary door (you can just see the ridge in the dome piece for the primary door that was supplied with the kit).

First though I should really trim the insulating board back! Perhaps should have done it before wrapping, too late for that now though. I may be lazy instead and put a waterproof membrane over it before cement and tile finish.

Thanks, the photo makes the brick work look neater than it is, side on it looks a lot more rustic! Part of the fun of reclaimed bricks and no previous brick laying experience .

[cherrycolavodka]

How is it nixie? As good as your first or better? I too have left my oven behind and I'm thinking modular for my second. Would love to know if you've found any differences?

[james34]

We are just commencing putting our mezzo oven in. Your pictures and information are great. Do you have any images of the oven insulated? Assuming that you have done this.
Also did you manage to get the internal floor of the oven flat between the two pieces when put together?
Thanks

[nixie]

Sorry not been on here much for a little while. I'm frantically trying to get a load of DIY done before arrival of our second monster! We have found time to use the oven a reasonable amount and I'm now getting much more comfortable with it.

Overall I prefer it to my first. It heats up a lot quicker and is easier to light (though I might just have improved my technique). I'd prefer the larger floor I had before however I've now started keeping the fire at the back while cooking (previously had it to the side and then move it periodically to keep the base warm). This makes it much easier to manage two pizzas in the oven at the same time. I had no issues cooking for 25 people this weekend gone with only a single base reheat (by move the fire over the whole floor and increasing its size) during that time. We have also done a roast in it which came out well. My wife things it was a bit too smokey in flavour, I have my suspicion this may be down to having to use more fuel in the fire to keep the temperature right due to not yet having insulated the oven.

The build however is not yet finished and other than stacking bricks to plan the outer arch I've not progressed at all, its not even insulated yet! Our new baby is due soon and I'm hoping to sneak a little bit of work in whilst on paternity leave.

james34, no I didn't get them perfectly flat though the are pretty close. I used a thin sand layer between the base pieces and insulation board and spent some time adjusting this till they were close. I've notice that the height difference does vary a little while firing. Before I started using the oven I thought the step would be a pain, but in use you don't notice it and it doesn't cause any issues.