Outdoor fireplace

[Sjcampbell]

Guys,

Just in the early planing stages of an outside fireplace. It will just have three sides and be made of concrete block. The base will be 200 mm of the ground so I don't have to bend as far. The inside dimensions will be 650 x 450mm.

My question is should I line it with firebrick or will the concrete block survive?

Ultimately I may weld up a Santa Maria grill to fit it

[Bear]

Concrete can explode at high temperatures, from my understanding

[Gumb]

Hebel blocks and a good fire grate. If you want it to draw properly it must be done right. we've built two recently using second hand Jetmaster open fire inserts surrounded by hebel block. Brilliant. you can pick them up cheap as people are pulling them out of homes and installing those real flame gas types. Just a wire brush, high temp spray and they are good as new. I've got some pics I can post if you want to check one out.

[Sjcampbell]

Gumb,

Pics would be great

[Gumb]

I'll put up some of our work when I get home but this is the general idea, only we did it outside>

https://www.youtube.com/watch?v=JB4bWij0D5U

[Gumb]

OK here's a bit of a walk through of how we built the outdoor fore place at the end of a covered pergola.

First we built the stand


Then we built hebel blocks around it. Hebel is available from Masters and just glued together, very easy to do. We were lucky to have borrowed a hebel saw which made cutting the blocks very easy. Note that the fire box is sitting on hebel too.



The we sealed the top, again with hebel.





Then the frame was built. A sheet of blue board was then attached to the frame. The blue board was also put around the frame at the back and over the top of the hebal. You have to have good insulation because these fire boxes get mighty hot. Without the hebel, the blue board will eventually catch fire.



The blue board was then rendered and the side frames built



And in the end it looks like this...



Hope that helps.

[burb]

Beyond impressed, what an awesome looking job Gumb.

[Bear]

+1 for hebel. I used reinforced hebel under my wood oven, see below. It's strong, easy to manage, versitile and a good insulator.

[Gumb]

Beyond impressed, what an awesome looking job Gumb.

Thanks. My son is a builder and my good mate sells and installs these things...it helps. There's an flat metal surround which we just glued on with silicon to finish it off which just goes right around the outer edge of the fire box and covers the gap you can see between the fire box and the render, but I don't have a pic of that in place.

[Sjcampbell]

Gumb,
Awesome stuff

[Sjcampbell]

Actually what I had in mind is similar to this on BBQ Brethren site except I will only have three sides, so I can toast my feet
The inside of this is lined with firebrick - and the $64 question is - is it necessary or a nice to have. My plan is to have it 800mm high so I don't have to bend too far, and that's 4 blocks high. I remember my parents first BBQ over 50 years ago, and it was concrete block only but I suppose we didn't have big fires in to.



....and then I can weld up a Santa Maria grill

[Gumb]

Looks good and i suppose it depends on what you want. While it's great for cooking and looks the part, I'm not sure how much heat you'd get sitting around that on a chilly evening unless it was roaring. But as I said, I like to look of it and it depends on what the main function you want is. Whatever you do, have a chat around an open fire with a beer or three is hard to beat.

[Sjcampbell]

Looks good and i suppose it depends on what you want. While it's great for cooking and looks the part, I'm not sure how much heat you'd get sitting around that on a chilly evening unless it was roaring. But as I said, I like to look of it and it depends on what the main function you want is. Whatever you do, have a chat around an open fire with a beer or three is hard to beat.

That's why I'll only have three sides on mine, rather than totally enclosed nice open fire with a beer!

But the question remains - do I need to line it with firebricks?

[Angryman65]

Concrete is a versatile product but not designed to handle the effects of fire for extended periods or be shocked by sudden temperature changes. It also absorbs moisture from rain or just the ambient humidity in the air and this can also impact on the fire itself as the moisture is drawn from the concrete.

A phenomenon known a spalling occurs when concrete fails due to heat, bits break off and they may fly about a bit. Remember the old fibro popping and flying about, same thing happens. The last thing you want when your having a relaxing beer in front of the fire is hot concrete flying at you.

When concrete is wet or holding moisture the fire itself will struggle and draw moisture from the concrete resulting in incomplete combustion and the production of "dirty" smoke.

Fire bricks may add to the cost and time of the build but will save you having to do it again should it start to fall apart.

Why not just build it from a combination of red commons and fire bricks for the pit area and render the outside?

[Sjcampbell]

Angryman,

Good advice. I was going to use concrete block because there are less blocks than bricks and I am the worlds worst brickie. The commons and fire brick sounds like a good idea - I'll just need to call in a couple of favours down the pub with a mate that's a brickie/tiler.