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Outdoor fire place (Chimenea) from ferrocement

Step 14: Final thoughts

So, what is there for version 2.0 (which I am very keen to make)?

- rimar2000 suggests using "expanded metal" sheets instead of chicken wire. It is apparently cheaper and from the looks of it it is ticker and the gaps are smaller so you might need less layers.

- Try to make the design look more like an actual tiki (by putting the fire in it's belly)
- Make the walls thicker to get better heat retention and radiation
- Use white cement instead of gray to get better colours
- Make the chimney wider, it will pull better
- Maybe use normal, cheap (gray) cement for the inner structure and finish with (coloured) refractory cement or clay.
- Make a tray to insert a BBQ grill rack
- Try to make the insides of the eyes glow with fire when all surroundings are dark
- Try not to cut my hands a hundred times on the chicken wire

I've had great fun designing and building this small devil and have enjoyed it's warmth a couple of time already. If you are thinking of creating a free-form structure that needs to be cheap, strong and durable I can highly recommend ferrocement although you might want to do a small proof of concept first to get used to the technique.

Good luck!

Matthijs



 
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rvwessel3 years ago
One thing you didn't mention was the 10:1 (opening size compared to chimney size) ratio needed for a proper fireplace draw.

I used a refractory cement mixture for mine to avoid it breaking down. My ratio was 3 sand, 2 plastic cement (I was told this was stickier), 1 fire clay. I forgot to buy lime and when I called back to the shop was told it was not necessary. What is the purpose of lime anyway?

Completed 3 days ago. Can't wait to give it a try!
thijsatteiltje (author)  rvwessel3 years ago
Good point about the ration between the chimney and the opening. I was only slightly aware of this and on this project have not taken it into account at all.

My experience is that the chimney could be wider or, that their should be more roof-spanning-space between the top of the opening and the bottom of the chimney.

I'm working on a wood fired pizza oven at the moment and that design is very clear that the height of the opening (or bottom of the chimney) should be set at 63% of the height of the dome. So there is quite a bit of theory about this.

Not sure about the lime. In clay ovens it is used to make a waterproof outer layer. Not sure what it does in cement.

Good luck!
I only had enough chicken wire for 3 layers except around openings where I made sure to have 5 layers. My base was rectangular (stand from an abandoned coin operated newspaper dispenser.) From the corners I created a frame of 1/4 inch metal rods coming up and a little past a 1/4 inch metal rod ring that defined the basic size of my chimney. My chicken wire pattern was random as I just cut and then wired in pieces as the structure seemed to need it for strength. There ended up being about 1/2 inch of space between the inside and outside layers of chicken wire. Filling that space and putting a layer over both sides made my cement about 1 1/4 inch (3 cm) thick. Do most ferrocement structures have thinner walls?

I'm wondering if the walls will become hot and radiate the heat or if the fire clay (refractory cement mixture) will prevent this effect.

As it is, with my chiminea standing 4 feet 7 inches (140 cm) and cement even making up the chimney, it must weigh somewhere around 165 lbs (75 kg). How much did yours end up weighing?

Veel geluk met uw pizza oven!
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