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StaceyB2

Asphalt Flooring Under Kiln

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I've managed to locate a kiln off craigslist (it has a stand) and have had an electrician run a line out to my garage.  But now it has occurred to me that the asphalt that someone poured to cover up the cement garage floor is probably a really bad thing around a hot kiln (it was a bad idea in general as it's all cracked and uneven).  Should I put off firing the kiln to the spring when I can pour a nice large concrete pad for it? Would concrete blocks under the kiln suffice?   I have been throwing like crazy and want to get to firing but don't want to do anything stupid.  Has anyone dealt with a similar situation?  Thanks so much for any advice in advance!

 

 

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I'm not sure which kiln you purchased, I put my Skutts on stands with steel casters (for different reasons as mine are on porcelain tile over concrete backer board). A similar setup would allow you to move the kiln easily and check to see if the subsurface is providing adequate insulation. Since asphalt is combustable (petroleum products), you might want to check and be sure you're not approaching the combustion point or just melting it and affecting the quality of the surface beneath your kilns. It probably won't be an issue, but then I'm overly cautious about fire and safety issues.

 

Mike

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You might be able to just put a piece of cement board on the floor; the kiln is on a stand, which provides air movement and space between the kiln and floor.  Raising on cement blocks might make the kiln too tall for comfortably loading/unloading (assuming its a top loader).  If you have doubts, give the kiln manufacturer's tech guy a call and ask. 

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Thanks for the responses.  The kiln is smaller 3.3 cubic feet Gare I got it for a dream off craigslist (pristine new condition - only fired a few times/lots of accessories/digital controller).  I hope to upgrade to a 5 or 7 cubic foot L & L in a couple of years after I figure out what my needs are.

 

I'm not tall so raising it up will make it difficult but I can probably work around it.  The cement board with bricks or pavers is kind of what I was thinking based on my internet searches.  Not being familiar with cement board...would I put it under or over the bricks?

 

I was also planning on putting a fan a few feet a way between the kiln and garage door opening to draw in cool air towards the kiln.

 

As a  permanent solution...do you think a large poured cement slab could go over the asphalt or do you think the asphalt needs to be dug out?  We eventually plan on doing something to cover the uneven floor in the rest of the garage.  My husband is advocating for wood around a large cement area poured for the kiln but I really don't know.

 

So many issues have come up that I did not anticipate!  Electricians messed up and ran 50 amps to the garage instead of 100amps ...what a fiasco that was to fix!

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Stacey;

We fired five kilns on hardwood floors in an old warehouse for years. The new owner put tin sheeting under each kiln for insurance purposes. They never got hot under there.

You could do it for your own calmness, but it is not necessary.

TJR.

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How about just cement board and then the stand-forget the bricks

if you want bricks go with cheaper chimmney firebricks laid in the 2 1/2 inch plane from a lumber store-this will not add much hieght and is not needed really.

Mark

Idaho Potter likes this

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Stacey;

We fired five kilns on hardwood floors in an old warehouse for years. The new owner put tin sheeting under each kiln for insurance purposes. They never got hot under there.

You could do it for your own calmness, but it is not necessary.

TJR.

 

+1

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I assume this kiln is off the ground on some type of metal legs. Modern electrical kilns are fine 30 cm away from the typical walls. So, if you expect your kiln to leak 451 F over 1 foot, something is wrong with your kiln insulation.

 

BTW, while you are waiting for your asphalt floor to melt and burn, read the book "Fahrenheit 451" by Ray Bradbury.

Cheers!

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I was under the impression that asphalt softens around 250 degrees...have read Fahrenheit 451.  Not expecting it to get super hot under kiln but who knows as I have never fired it before.  I was thinking that the biggest risk is the contact points where the kiln stand meets the asphalt.  Likely the legs would just settle in the asphalt if the asphalt were to soften, but the idea kiln possibly shifting during firing is not super exciting to me.   I tend to be one of those people that strange and rare events happen surprisingly frequently, so life has taught me caution. 

 

I will probably use two layers of the backer board or one layer of backer board and the thinner bricks.  Thanks for the responses :)

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I wouldn't be too concerned with the asphalt softening. The kiln insulation does its job extremely well. Even around 2000 F the exterior is only a couple hundred, and from there the heat dissipates quickly. Any heat transferred to the metal legs is quickly lost before it makes it to the ground.

 

A good example of how well insulated the kilns are, I had my classroom kiln around Cone 05, and a student at the closest table, quickly grabbed a stack of papers in a swiping motion. This caused some of them to fly outward and some actually got stuck in the tiny space between the metal skin and kiln brick. It's one of those things that you couldn't do if you tried a thousand times. Anyway, the paper did not combust. Even the tiny pieces I had to pull out, only slightly darkened.

 

Don't get me wrong, it is a good idea to be overly cautious when setting up a kiln. But unless you are setting up your kiln in a structure made of gasoline soaked rags and newspaper, you should be fine with just keeping the kiln a foot away from the structure on all sides.

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I wouldn't be too concerned with the asphalt softening.

I'm not sure about this. Before I renovated my studio, my kiln was sitting on a vinyl floor. Everything looked fine, but when the kiln was moved during the renovation, I discovered that the kiln had softened and left dents in the floor. I would think that asphalt would be more vulnerable to this than vinyl. When I put the kiln back in place, I put thin bricks under the feet. I agree with others that the kiln is insulated enough to not start a fire, but if the feet sink into the asphalt you may have an unlevel kiln. I think your backer board solution sounds good.

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I wouldn't be too concerned with the asphalt softening.

I'm not sure about this. Before I renovated my studio, my kiln was sitting on a vinyl floor. Everything looked fine, but when the kiln was moved during the renovation, I discovered that the kiln had softened and left dents in the floor. I would think that asphalt would be more vulnerable to this than vinyl. When I put the kiln back in place, I put thin bricks under the feet. I agree with others that the kiln is insulated enough to not start a fire, but if the feet sink into the asphalt you may have an unlevel kiln. I think your backer board solution sounds good.

Could the marks in the vinyl just have been from the weight of the kiln, especially when fully loaded?

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Stacey;

We fired five kilns on hardwood floors in an old warehouse for years. The new owner put tin sheeting under each kiln for insurance purposes. They never got hot under there.

You could do it for your own calmness, but it is not necessary.

TJR.

 

Kilns should never be placed on a wood floor. The danger is not that it gets so hot that the floor will burst into flames any time soon, but that with each firing you are drying out the wood and lowering its flashpoint, so that someday in the future it very well may catch fire. Metal sheeting is not ideal, as it conducts heat very well. A simple and cheap solution to putting a kiln on a floor that is combustible is to place 2 layers of cement board (tile backer) under the kiln, extending at least a foot beyond the kiln. This goes for vinyl, asphalt, wood, etc.

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I wouldn't be too concerned with the asphalt softening.

I'm not sure about this. Before I renovated my studio, my kiln was sitting on a vinyl floor. Everything looked fine, but when the kiln was moved during the renovation, I discovered that the kiln had softened and left dents in the floor. I would think that asphalt would be more vulnerable to this than vinyl. When I put the kiln back in place, I put thin bricks under the feet. I agree with others that the kiln is insulated enough to not start a fire, but if the feet sink into the asphalt you may have an unlevel kiln. I think your backer board solution sounds good.

Could the marks in the vinyl just have been from the weight of the kiln, especially when fully loaded?

The floor around the dents was a little distorted and buckled, more than a simple dent. Besides if weight alone caused it, that would still spell trouble for an asphalt floor.

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So my husband thought it over and went with a layer of cement bricks (about 3 inch bricks with air pockets) with a cement slab over the top.  The stand is about 6 or 7 inches off the ground.  thanks for all the input!

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