The Picton Pizzeria

[ihughes]

After 3 weeks of weather finally got to finish the stand. Although when your 4-year-old is ''helping'' it may be more fun but it does take twice as long

Hoping to speed things up now but I have a question about the framing for the hearth.

• I was going to buy cheap pine from the local hardware store and burn it afterwards to cure the oven. The thing is that I can get recycled hardwood for the same price. Is there any problem burning pine in the oven as long as it isn't treated and properly dried? Or am I better off with the hardwood?

Or does it matter and I should just go with the closest option

• Also, we're planning on some moroccan tagine cooking. Is a higher dome better or should I go with a lower one as long as it accommodates the tagine? Any opinions/experience welcomed.

cheers, Ian

[wlively]

Re: The Picton Pizzeria

I used pine to frame mine. It was left over from tyhe patio project. The only pieces I have burned were a few 2x4 scraps and some 1x1/2 stakes and they were no problem at all.

My suggestion would be to go with what is cheaper, that being equal, what could you use later? Which would be better for finish out or other projects?

[maver]

Re: The Picton Pizzeria

Although pine is cheaper, it's not as nice to burn as hardwood (weak flames, lots of popping), so if they are equal (price and useability) I'd get the hardwood.

[RTflorida]

Re: The Picton Pizzeria

I would say long term burning of softwoods (pine) is not a good idea, fro the same reasons listed by Maver as well as creosote/tar build up in the chimney.
That said, burning a few 2x6 or 2x8 during the curring or in the initial larger fires shouldn't be a problem; just don't make a habit of it.

RT

[ihughes]

Re: The Picton Pizzeria

Thks. I thought the pine might not be as clean to burn.
I think I'll go with hardwood and use it after for benches etc

cheers
ian

[ihughes]

Re: The Picton Pizzeria

After a couple of weeks of bad weather finally got started on the framing for the hearth. Measured three times and still had a wrong measurement for the plywood base. In dividing the overall area in to 2 equal rectangles I ended up with 2 rectangles that would only cover half the area.
Luckily I picked up the mistake before getting the hardware guy to cut it for me so I've left that for another day after I recheck the measurements.
Measuring three times cutting once is a good idea but it looks like I need to do a bit more.
Anyway, got it half done today, hopefully the weather holds and tomorrow I'll get the frame finished and start calling friends to help pour the concrete and vermiculite.

[Archena]

Re: The Picton Pizzeria

Okay, I'm not clear on how you're calculating this thing. If you're trying to derive the area of your rectangles from the area of the circle that's where trouble started.

If you want two equal rectangles to overlap the oven then measure the diameter (length) and width of the oven. Multiply the length by 1/2 of the width (actually the radius). The result will be a rectangle that overlaps the exterior and is half the width of the oven. (In blue on the diagram).

If you want two equal rectangles that fit inside the oven you need to decide how you want them to fit. From the side touching the oven walls measure the length you want then measure the distance from the point touching the wall to the centerline of the oven. (In red in the diagram). You can adjust this to whatever dimensions you want - you might want to use a piece of cardboard to better visualize how the thing will fit. (In the diagram I used more than one possibility - all are rectangles, however). Then have two of them cut.

Basically, if you want them to fit inside it requires eyeballing then measuring. The area of the circle really won't help you much - it's the area of the rectangle that you need*.




Hope this helps! If not, forward any complaints to: www. quitannoyingme. pht**






*You can get closer using the derivative but who wants to do calculus? If you're trying to maximize the area then you'd need to do that - I'm not so good with calculus...
**No, it's not a real website...

[Unofornaio]

Re: The Picton Pizzeria

Thks. I thought the pine might not be as clean to burn.
I think I'll go with hardwood and use it after for benches etc

cheers
ian

If you want to re-use the form wood you can coat it with a very strong solution of liquid dish soap (I think you guys refer to it as washing up liquid) and water in a pump sprayer. Coat the forms several times, wait between coats a little bit (if it drys between coats it works better) I usually do it the day before the pour and then the same day.
This is just as effective as form oil but will not ruin the wood for later use like form oil or diesel will.

[ihughes]

Re: The Picton Pizzeria

Finally finished the framing for the hearth slab. Remind me next time to get someone to help hold the various bits of wood when putting it together (next time!!) Would have saved a lot of time. I've posted some pics in the hearth and stand photo gallery.
http://www.fornobravo.com/forum/photoplog/index.php?c=1

I've used builder's plastic on top of the plywood instead of oil or dish detergent. Is there any problem with that? I won't be pouring til next weekend at the earliest so I can always change it.

I've used 200x50 wood for the box. How essential is the cargo strap to keep the boxing in shape when I pour the concrete? Could I nail a 100x50 across the top instead? Apart from getting in the way are there other considerations?

ian

[Hendo]

Re: The Picton Pizzeria

Ian,

A few observations from my build if I may.

I built my formwork by myself without too many problems, one side at a time. I think the main reason it didn’t prove problematic is that I didn’t have to cut the support legs to exactly the right height, as I attached them to the outside face of the timber planks, rather than underneath. As a result, it was very easy to adjust the height of the formwork on each side, prior to fixing the legs. After fixing the legs, each form assembly was quite stable when fixing them all together. See first pic below.

The second is that I screwed some small blocks to the ends of the timber forms on each side of the hearth slab. These enable the screws which secure the assembly to be fastened into cross-grained timber in all corners, rather than into the end-grain of the adjacent timber form. A much stronger joint results, and eliminates the need for strapping to keep everything together. The second pic shows this in detail for one of the corners.

Lastly, I threaded some wires through the timber forms from one side to the other, and tensioned them to prevent the formwork from bowing out during the concrete pour. These obviate the need to brace the centre of the forms with angled props, so you don’t end up tripping over them during the pour! In the first pic, you may be able to make out two angled wires running from left to right, tensioned with short lengths of rebar, and one twisted one going from top to bottom – where a small metal plate prevented it from cutting in to the timber form. Worked a treat, and didn’t get in the way of the pour like pieces of timber nailed across the top would – in fact they became part of the pour, and the slab!

Hope this helps.

Paul.

[Archena]

Re: The Picton Pizzeria

I think he wants to reclaim the wood though. Still, a dual twist in the wire ends like you used would let him do that easily enough. He could easily cut through the twist afterwards then grind the remaining wire flush. Since I doubt he's going to be reusing it for anything showy the holes shouldn't be a problem - not one wood putty wouldn't solve, anyway.

I know plastic isn't used on anything on which the bottom will show (like a bird bath). That's because any wrinkles in the plastic will be mirrored in the concrete. Depending on your design that might actually be desirable - the edges would have a bit more character and would likely look good with stucco on the oven itself. The underside would of course never be seen and as far as I know the few wrinkles there wouldn't compromise the structure - I can't actually imagine how they could.

A light coat of oil on the plastic might help with removal - but shouldn't be essential.

[Unofornaio]

Re: The Picton Pizzeria

"I've used builder's plastic on top of the plywood instead of oil or dish detergent. Is there any problem with that? I won't be pouring til next weekend at the earliest so I can always change it."

Plastic is not really a problem. Some notes of caution about pouring concrete in "direct contact" with plastic:
Because the plastic creates a "barrier" this rapidly accelerates the chemical heating process in the concrete, I would not suggest doing this in hot weather as you most certainly will have overheating/rapid set up issues with the slab. If you are mixing bags, on a hot day this would seriously compromise the strength of the overall slab. I think its winter there now right? so you should be OK what ever you do DO NOT COVER the TOP after the pour with plastic or anything that cant breath and keep it watered down religiously for the first 24 hrs.
Secondly where the plastic is creased or folded (on the 4 visible sides of the slab) the plastic will stick into the concrete this is not an issue as you can stucco or parge coat right over this area. Don't be tempted to pull the plastic out too soon you may not know how badly it was folded an could pull out a nice chunk of slab. After taking the forms off cut the plastic off in these areas. There is usually a bit right next to the concrete you cant get and we just use a propane torch to melt it so its not visible (if you leave this small piece and you are planning on stuccoing over it you will regret it.) The other areas that are not creased will come out very easily and there is no need for additional release agents.
Sounds like you are ready to go..Good luck

[ihughes]

Re: The Picton Pizzeria

Thanks for the great comments.
I think I'll go around the frame again and strengthen it as Paul suggested.
I hadn't thought about the plastic and its effects on the curing.
If I cover the cement with old wet sheets will that do the trick? Temps here are generally in the 10-20Deg C at the moment although it can get a bit hotter (mid-20Deg C) on occasion.

[Archena]

Re: The Picton Pizzeria

I'd think sheets would be too permeable - the concrete would stick to them and the wood.

[Hendo]

Re: The Picton Pizzeria

Ian,

From the photo of your formwork at http://www.fornobravo.com/forum/phot...arth-floor.gif, it appears that you?re only using the plastic over the plywood base ? so appearance on the sides from plastic creases shouldn?t be a problem. And no-one will see creases in the concrete under the hearth slab except the wood gatherer!

As far as covering the concrete slab after the pour, if it were me, I wouldn?t hesitate covering it as soon as it has set with a plastic membrane. I had an impervious membrane under my slab ? steel flooring ? and covered the freshly poured slab with plastic after 12 hours or so. I gave it a good hose down first, and during the next 7 days I ensured that it remained moist under the plastic. It actually stayed like that for 28 days as there wasn?t any action going on ? at least on the hearth slab. This was late February and quite warm. The idea is to keep the concrete moist to ensure those (exothermic) chemical reactions continue so as to achieve a good strong slab.

See my post at http://www.fornobravo.com/forum/16/o...+cure#post7244 for more info on moist curing, including advice from the Cement and Concrete Association of Australia. I?ve always favoured plastic film over the concrete as it retains moisture more reliably than sheets or hessian etc. which you have to keep hosing down. You can just cover it and forget it basically. I?ve taken my cue from the many building sites which adopt this practice.

Good luck for the pour next weekend!

Cheers, Paul.