Hoping to choose & begin soon in Chch NZ. Thoughts required.

[uk_exile]

We decided we wanted a pizza oven after seeing a demo at a building expo but their commercially built oven was too expensive ($4-8k just for the oven). Then found The Shed magazine articles and began planning how to build our own. Even managed to score some house bricks free from the recent earthquakes. However more recently discovered this website & that The Shed design using standard house bricks isn?t likely to be long lasting, and doesn?t have insulated base etc. Given the time and expense we?d like something that will last and work really well so we?ll now looking to two options
1) Building a Pompeii, or
2) Using a precast kit
Precast would be something like Ovens - Welcome to the website of Hard Yards, manufacturers of Wood Fired Pizza Ovens, Ornamental Outdoor Furniture, and Wood & Gas Fired Braziers - Hard Yards, manufacturers of Wood Fired Pizza Ovens, Outdoor Furniture & Fire Pit Tables). The almost complete kit is tempting at $1850 inc GST as it?s quite likely cheaper than building a Pompeii with fire bricks being $5 each.
Any kiwi?s on this forum used the Hardyards kit ? Or similar ? Canterbury Clay Pavers have something very similar but not a complete kit. Dome & arch is $711.11 + GST & they estimated $1500ish for everything.
I contacted the NZ dealer for Do It Yourself - DIY Woodfired Pizza Oven Kits - Mediterranean Woodfired Ovens but that kit is $2900 inc GST
The other NZ one I?ve found is Pizza Oven Kitset List and Price at $2990 inc GST

Have tried contacting Forno Bravo NZ too but no success. Do they still exist ? Perhaps it just time of year, Summer holidays ?

The Pompeii could last decades or more but not sure about the cast domes. Any expereicnes with them long term ?

As far as design style goes we?re wanting contemporary. Most on here seem to be very traditional olde world, exposed brick, stone, curves etc. Ours will be housed in steel framed Hardie board box and lightly rendered. Straight edged to give contemporary look. Being near coast the easterly breeze is cool most evenings so we?ll be creating a protective courtyard using block walls. Maximum 2m high as above this needs building consent from city council. Wanted a partial roof too but that would need a resource consent requiring approval from all neighbours, etc hence decision to just have a fabric shade sail over it.

I?ve attached 2 photos of where it will go (1 prior to recent window & door replacement) and two sketches of our current ideas.

I can for see this project taking at least 12mths to complete????and costing somewhere in range of the first commercial oven we saw??..

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

Another question, concrete block walls 2m high, do I need to mortar each block together, reinforcing steel and fill, or can I just dry stack, reinforce and fill ? Will be rendered.

Bearing in mind we've had almost 4000 earth quakes in city since Sept 4th
Canterbury Quake Live

Does mortar between each make cracks less likely ?

[Lburou]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

Another question, concrete block walls 2m high, do I need to mortar each block together, reinforcing steel and fill, or can I just dry stack, reinforce and fill ? Will be rendered.

Bearing in mind we've had almost 4000 earth quakes in city since Sept 4th
Canterbury Quake Live

Does mortar between each make cracks less likely ?

Good looking back yard you have there. The windows made a big improvement in looks.

I'm sure dmun will chime in here, but what you need in those walls is steel reinforcement and a good footing. Then, fill enough cavities (with steel in them) to make it stable no matter what.

Somebody will chime in here real soon with a prescription for your wall construction. What size are your quakes?

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

Thanks re comment about our existing outdoors area. We were going for standalone pizza oven but have decided while doing it that it's about time the whole area got a makeover since we've changed the look of the house so much in the last two years. The house had been looking quite dated (built 1970) and I'd become fed up burning off old paint, sanding, priming, undercoating and top coating the wooden windows neglected by previuos owners. So we replaced the old arched wooden windows and french doors with double glazed aluminum windows and bifold doors. The bifolds make a huge difference. Very pleased with them. It's great being able to open up the whole dining room wall rather than just the two french doors in centre. The roof wasn't in great condtion either (old decromastic steel tiles where most stone chip had fallen off, badly faded and had been recoated sometime in past) so it was replaced with new Gerard tiles. Gutters replaced and colorsteel fascia added. Strangley an elderly neighbour wanted us to keep the old arched windows !!!! House has gone from 1970's to 2000s and from retro much closer to the contemporary style we prefer :-)

I knew I'd need decent foundations and plenty of steel reinforcing plus filling. My question related to need to mortar, or the labour saving method of just stacking all the blocks directly together (avoiding mortar).

Lived most of life (except 6yrs in UK) and only ever felt 3 small non damaging earthquakes. That was until Sept 4th 2010 when a previously unknown fault line appeared close to city with 7.1 magnitude quake, knocking down many buildings and causing large amounts of liquidfaction in some suburbs. I'm very lucky to be in suburb with good soil and only have very very minor interior plaster cracks. No lives lost though, mostly due to occuring at 4:30 in morning and our generally good building standards. In comparison the less 7.0 magnitude Haiti quake killed 250000+ people.
To further answer you question re size most aftershocks now magnitude 3 to 4 so the type you don't feel unless stationary.
Quake Years has some great graphs of what's happening.
Canterbury Quake Live
Canterbury Quake Live

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

I had a chat with a friendly structural engineer and he said definitely mortar between each block while laying them. Said the mortar does add a small amount of strength (but negible in overall context) but it's main reason is to prevent movement while filling and would be very difficult to get a vertical wall without mortar due to block tolerances

[Lburou]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

I had a chat with a friendly structural engineer and he said definitely mortar between each block while laying them. Said the mortar does add a small amount of strength (but negible in overall context) but it's main reason is to prevent movement while filling and would be very difficult to get a vertical wall without mortar due to block tolerances

I'd be interested to hear what his recommendation for steel reinforcment was.....?

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

For foundation sizing, reinforcing in foundation & wall he simply recommended grabbing leaflet from local supplier or from their websites. Also suggested getting precast concrete slabs made off site and craned in might be a viable option for me rather than making walls with blocks.

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

These links might be of interest to many

Precast outdoor fires
http://www.firth.co.nz/media/101678/...ochure_web.pdf

Fences, foundations, blocks reinforcing etc
http://www.firth.co.nz/media/69837/F...20Oct%2009.pdf

Block specs
http://www.firth.co.nz/media/69313/H...0Sept%2009.pdf

[Lburou]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

For foundation sizing, reinforcing in foundation & wall he simply recommended grabbing leaflet from local supplier or from their websites. Also suggested getting precast concrete slabs made off site and craned in might be a viable option for me rather than making walls with blocks.

Sounds expensive to me, compared to doing it yourself.

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

He thought it may not be more expensive as I'd need to buy blocks, reinforcing rod & the materails for concrete fill all at full price whereas a precast contractor would get much better material deals, could use cheaper reinforcing mesh rather than rods & be able to easily use their factory formwork is keep to standard sizes. Being small panels could use delivery truck Hiab rather than mobile crane to place them too. Save me heaps of time. I'll definitely get a quote.

[DimTex]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

For the slab which is what I think you are talking about I scrounged around and found some old heavy gauge mesh shelves, the industrial kind and some lengths of angle iron and wired them together and made sure to suspend them in the concrete before the pour. The thing I learned before doing this was that curing makes a big difference in how strong the slab ends up. I poured the slab, kept it wet for about four days by soaking burlap on top of the slab. Then I let it cure for 3 weeks with no load before I started my construction. According to the Portland Cement Association (has a lot of data on this topic) the length of time for curing has a direct impact on the final strength. In short, take your time, lots of time.

As far as the build time after slab, unless you want it to, it should not take 12 months. I built mine on weekends and evenings and it took 3 months. Some folks build them faster but my son and I took our time.

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

Got a quote for a contractor to build the 11m of 2m high fence via precast concrete slabs. Aprrox $7500 !!!!! So it'll be concrete block.
I'll build the foundations for the fence & oven but will get a block layer to lay the blocks for the fence as would take me many days to lay 300 or so blocks with my lack of skills. Decent block layer will do it in a day ??? Better to pay someone skilled and save myself many many days labour.
I'll fill the fence blocks myself after block layer is finished and will then I'll lay the oven base since those blocks can be dry stacked.

[dmun]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

Decent block layer will do it in a day ??? Better to pay someone skilled and save myself many many days labour.

Yes, for something that's so commonly done, laying concrete block is surprisingly difficult. If you can get help with this, it will save your time (and your back)

[Neil2]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

I, too am in an earthquake zone. The trouble with using precast sections is the issue of tying the structure together to prevent sheer failure at the joints resulting from the horizontal acelleration in earth quakes.

An important detail is to tie your at grade slab (or foundation) rebar to your wall rebar and to tie your wall rebar to your suspended slab rebar.

For example, when pouring an at grade slab, have at least one, preferably two, rebar at each corner bent 90 degrees with about 18 inches sticking up vertically.

To these verticals, tie your wall rebar with that in turn having at least 18 inches bent horizontally to tie to your suspended slab rebar.

Use rebar (3/8 or 1/2 inch) not WWF (welded wire fabric or "mesh").

[uk_exile]

Re: Hoping to choose & begin soon in Chch NZ. Thoughts required.

Seems to me as a complete newbie that
Size = How many items you can cook at once and how even the heat will be. Larger diameter gives larger ?sweet spot? & more space if need to keep some fire going
Dome thickness = How long it takes to heat up. Thin gives fast heat up but not large energy storage for high volume cooking at near constant temperature
Insulation = How long it retains heat.

These 3 seem to be the overriding factors. Given that what I?m tempted to go for is larger size like a 42? but with thinner floor and dome, with a sensible amount of insulation. My selection is based on ideals that pizza will be frequent, often for just family, not always a party, and other cooking will be single baking overnight, not over many days, or big volumes for dozens of people. So 1/3 bricks rather than halves. Good plan ?

There are obviously other relationships between each
Thickness & Insulation = how much energy is stored & how well it?s retained = controls volume of food & duration of cooking i.e. lots of insulation isn?t going to allow long duration cooking if a large volume of food sucks all the stored energy out & large mass isn?t going to be complete answer if it all leaks out to air
Size & Thickness = bigger size allows bigger fire but it doesn?t mean a bigger fire gives shorter heat up time as mass of dome is not proportional to diameter
Other relationships too.