900mm Pompeii build in Westleigh, Syd

[dariusk]

Hey there
I have finally made a start with my full size oven after many years of thinking, planning, procrastinating. I am glad I put off the start in previous years though, as we now have no plans to move house again for a long time, so should get many years from the oven. A part of the hesitation in starting the build was not being sure on the size to build, along with minimal brick and building skills, but I'm over that now and the plan is to just build it rather than spend months considering if each part of my plan is perfect or not. I realise there are a few pitfalls with this approach, but I'm confident it will come together in the end.

So here is the start, site selected, area cleared and prepared, forms and reo in and then slab poured. This was last weekend and now I'm playing with the design of the stand with loose blocks. The slab dimensions are 1900 x 1500mm and at the moment the stand is planned for 1750 x 1450mm. I realise this puts the side blocks quite close to the edge but I decided to try to maximise the width and will be inserting an extra 90mm block between the three 390's and one 190 blocks. Hope that makes sense. Yes, I already wish I made the slab a bit wider! Any thoughts on if 20mm space between blocks and edge is enough? I was originally planning for an 850mm internal floor, but have bumped this up.

I am more than happy throughout the build if anyone notices something I'm doing is not ideal or just plain stupid, to let me know in any way you like. I'm not sensitive and realise there is a lot I don't know. It would be much appreciated.

So I'll try and get a few pics up. These are ipad quality but will try for better ones as I go along..

Cheers
Darius

[david s]

It probably doesn't matter that much, but normally the blocks are laid the other way up ie. the thicker part at the top. I guess this is so it provides a wider part of the brick to take the mortar. If you are just dry stacking them it's a good idea to use masonary adhesive eg Selleys landscape adhesive.
You could also consider making the stand smaller and cantilevering the supporting slab over it. This has two advantages. Firstly it reduces the span and puts the support closer to where the main load will be and secondly it brings the load on you foundation slab away from its edges. The downside is that there is slightly more complex for work required for the cantilevered supporting slab.
Doing it this way also reduces materials required for the stand and IMO looks way better.

[dariusk]

Hey David
I'm guessing you are referring to 90mm wide blocks being the wrong wa up? They seem to be the only ones with any variation, having one solid surface, the other sizes are the same thickness both sides. Yes, planning to dry stack and core fill. I haven't seen of anyone using masonry adhesive on their stands here, but I'll look into it, thanks.
As for the stand, I'd rather not cantilever the top slab. I hoping I'll have enough width on the top without this and it will make my plan for the finish easier too.
Cheers
Darius

[david s]

Hi Darius,
As I said it probably doesn't matter that much if you are not using mortar anyway, but all concrete blocks I've seen are made with the inner core tapered so they can be removed from the mould easily. Maybe yours are made using a different process. My apologies if this got you worried. There maybe some little dags on the blocks that might make setting them level difficult, it's not a problem if laid with mortar because the mortar absorbs any minor inconsistencies. I knock them off with a trowel. Also if things get a little out of level I use some 5/16" washers to pack up the gaps and get back to level.

[Steady]

Looking forward to watching your build progress Darius

[dariusk]

Hi Darius,
As I said it probably doesn't matter that much if you are not using mortar anyway, but all concrete blocks I've seen are made with the inner core tapered so they can be removed from the mould easily. Maybe yours are made using a different process. My apologies if this got you worried.

Hey there David. No you didn't get me worried, just curious. I had a look at the full size 390mm and there appears to be minimal tapering, hardly noticeable whereas the half 190mm blocks are clearly wider on one foot. I didn't really pay much attention when laying them and agree I don't think it will make any difference which way they go. I did take your advice and used bth the masonry adhesive and used a washer here and there for levelling, worked great, thanks. After grinding for the angle iron the stand is pretty much up and staying up, as now plumb, level, square and stuck together! I'm pretty happy with the results to date. My wife even said 'it looks like a real one!'
I will core fill every second hole next and start working on the form work for the next slab.

Looking forward to watching your build progress Darius

Hey there Steady, welcome aboard mate, it could be quite a long ride though...!

[UtahBeehiver]

Great start on the base. Very good rebar layout in your base. Are you going to install any rebar in the cores to tie the hearth to the CMUs and the rebar in the hearth floor?

[cobblerdave]

G'day
Like the extra wood entrance... You've done your research well
Regards dave

[dariusk]

Thanks Cobblerdave. I figured having a side door will allow for better access to the rear space under the hearth slab. Also, the blocks running across the middle of the stand give me a sense of greater support for the slab above. I'm sure the reinforced concrete can handle that span, as I've seen a lot of builds here do it, but I just feel better having the extra blocks there holding up the centre. May be over engineered, but gives me peace of mind..

Great start on the base. Very good rebar layout in your base. Are you going to install any rebar in the cores to tie the hearth to the CMUs and the rebar in the hearth floor?

Thanks UtahBeehiver. I'm following the FB plans in general but happy to hear it is looking ok! Yes, there will be rebar in all the filled cores which will then tie into the rebar in the hearth floor. Sorry, not sure what CMU's stand for?
I've been wondering just how much need/value there is in tying in the foundation slab, stand and hearth slab? I understand it will make it all much stronger, but under what circumstances would this make the difference between survival and catastrophic failure....! Mine is in a residential backyard so I think the worst that's likely to happen is a bump with the lawnmower... I hope.. We are not prone to earthquakes and the like here. Anyway, a lot of work is going into it so I'm not going to skimp just in case!
Cheers
Darius

[UtahBeehiver]

Sorry, CMU is a Yankee term, stands for concrete masonry unit or concrete blocks. Since you are installing rebar in the cores no reason not to tie into hearth rebar, it is there anyway. Yes, I know what you mean about over engineering (I'm a retired engineer), I live in a earthquake area, my house will fall down during the "Big One" but my oven won't and I will be able to cook pizza....LOL.

[Steady]

Just checking in on progress - base looks good - I wish I had built in the side access like yours (next time I guess :-)

[dariusk]

Hey Steady, thanks mate. At this point I'm thinking this will be the only oven I ever make!

It's been pretty busy recently and I'm only managing to get a little time here and there over the last month or so. But a bit of progress has been made. Cores filled, gaps covered and now ready for the reo and form work for the hearth slab.
I'll spread pics over two posts...

Cheers
Darius

[dariusk]

And after today's efforts...

[oasiscdm]

Hi dariusk

Nice work, I too like the side access and will be doing that on my next oven that hopefully will start by year end.

[Steady]

Hey Steady, thanks mate. At this point I'm thinking this will be the only oven I ever make!
Cheers
Darius

It looks good Dariusk - I thought the same at a few points along my build but now I have finished.......