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Old 08-25-2005, 03:58 AM
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Join Date: Aug 2005
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Default Aluminium flashing

Hi everybody
I have a question about the layer of aluminium flashing. I'm not sure where to find this and how thick it should be. I have aluminium , but it's quite thick (about 2 mm) and I'm not sure if everything will stay in place that way once its heating up.
Thx for any advice on this
Jan
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Old 08-25-2005, 04:05 AM
dmun's Avatar
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Location: New Jersey USA
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Default flashing

Aluminum flashing is a roofing material, and will be found in a building supply store near the shingles and roofing material. It is sold in rolls, in various widths, and is about about .032" or .7mm thick. It's soft and easy to bend, and is used to waterproof joints between the house or chimney and the roof.

There is no reason why you couldn't use any thickness of aluminum, including the .080" or 2mm that you have found. If you have to buy it, though, it would be a lot more expensive and hard to work with than flashing, which you can easily cut with tinsnips.

David
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Old 08-26-2005, 10:05 AM
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Location: Pebble Beach, CA
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I wanted to get the consensus on whether builders think the aluminum flashing is necessary. The idea behind the flashing layer is to create a slip plane between the hearth and the block stand to allow accommodate different rates of expansion and contraction between the two oven elements. I wondered whether experience was showing there is enough heat in the bottom layer of the hearth to make the flashing necessary.

James
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Old 08-26-2005, 10:19 AM
Robert Musa's Avatar
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Location: Sacramento CA
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i found this on the web:

"An average value for the coefficient of thermal expansion of concrete is about 10 millionths per degree Celsius, although values ranging from 6 to 13 millionths per degree Celsius have been observed. This amounts to a length change of 5 mm for 10 m of concrete subjected to a rise or fall of 50C."

assuming a 2 meter hearth base this would translate to 1 mm per rise of 50 (C). that said, in an expansion battle between my block wall (with its concrete / rebar reinforced top layer) and my oatmeal cookie consistency vermiculite / concrete hearth base, there's no question who is going to win. i have the flashing but i figure that nothing is slipping; (just the faint murmer of vermiculite being crushed).
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Old 08-27-2005, 06:44 AM
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Join Date: Mar 2005
Location: Powder Springs. GA
Posts: 12
Default Flashing needed?

Hi all;

I mostly followed the Forno Bravo guideleines when I installed my Casa 110- but decided against the flashing. I did the 2 part pour on the hearth floor, using 3" concrete/vermiculite, then 3" concrete. I will take a few temp readings next time I fire, of the hearth layer from below, and on one of the exposed sides of the hearth floor (My oven is not totally closed in yet) to see what temps I am seeing through the layers. My last firing had the dome greater than 932F ( the upper limit of my infrared temp sensor) and the floor at 650F.

Stanley K.
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