Tom at Hutchtel.net on wed 17 aug 05
> Andy, wooden roof joist and posts over and around a wood-fired
> kiln are just not a good combination.
> As you describe it, everything sounds fine. The danger is that the
> unusual and unexpected might happen.
>
> For example, my shed roof caught on fire because, unknown to me,
> a spark escaped from the firebox and landed in a small pile of wood
> about 4 feet from the kiln.
An hour later, the roof was on fire - that small
> smoldering spark finally ignited the wood, which caused the flames
> to jump up to the roof structure and spread to the whole shed.
> My shed is now 100% steel.
>
We just had a potter visit from 90 miles south of us today. Talk got to
wood ignition because they had had a fire a few years back. They were
lucky...still in the studio and smelled it.
It was tracked to wood exposed to heat over the years. Got down to the
ignition point and poof. 160 degrees F is not very hot. You can touch it.
And it is radiant heat that counts. All the air in the world may not
overcome high radiant heat. Heat shields are important if you have to
have/use wood.
Because of this thread, I called our fire marshal Casey Stotts today. He
said wood exposed to radiation that brings the wood to temps as low as 150
Degrees F is undergoing the chemical changes that lower its ignition point.
Am I overly careful now? You bet. We were lucky/smart. We had good
insurance that covered all but $10,000 of the $78,000 loss.
Which brings up another point. How many of you are depending on your
homeowners to cover your loss? It won't if you sell pots even partially
commercially. Think about it kids....it isn't worth it.
And I'm getting the impression from this discussion that there are a lot
more fires than are reported in the statistics. If you're going to be even
partially in the business of making pots, cover yourself and do things
smart. Saving money on this kind of safety is well spent. Think about what
you're going thru to protect yourself from a little silica or other chems.
Go through the same effort on the fire issue. If you have questions, get to
a pro...not this list, including me.
Tom Wirt
Hutchinson, MN
twirt@hutchtel.net
www.claycoyote.com
Andrew_M_Casto@PROGRESSIVE.COM on wed 17 aug 05
Ok, so now I'm worried...
Several posts have addressed enclosed buildings, wooden and
otherwise...however I haven't come across anything concerning "lean to"
type sheds without walls. I have a 60 cu ft bourry box wood kiln which is
about 6 months old. We had previously been covering it with a very large
and elaborate tarp system. We finally built a roof over the kiln about a
month ago, but have not fired since then. This roof is 24 x 16, with wood
2x10's as joists, set on wood 4x6 posts, with sheet metal roofing. The
bottom edge of the joists are about 4 feet above the exterior of the kiln
arch, and the joists around the chimney are around 3 feet away from the
bricks. There are no walls on this structure...meaning that it is open to
wind, breeze, etc...it basically just keeps the kiln and our wood dry when
it rains or snows. Given the discussion of the importance of air
circulation, I think we are in good shape in that regard. My worry at this
point is the proximity of the wooden joists above the kiln. Does anyone
else think this would be a problem? My arch by the way is 4.5 inches of
hard brick, covered with fiber blanket and then a layer of castable. If it
does seem like the roof is too close to the kiln, what about using some
sort of coating on the joists? I remember a post about something of this
sort earlier. I also recall hearing about Nils Lou using ITC to cover a
plywood sheet that was placed in the door of his wood kiln while the door
was repaired during a firing...what about spraying the joists with ITC? Is
that overkill? Any help would be great.
Thanks,
Andy Casto
David Hendley on wed 17 aug 05
Andy, wooden roof joist and posts over and around a wood-fired
kiln are just not a good combination.
As you describe it, everything sounds fine. The danger is that the
unusual and unexpected might happen.
For example, my shed roof caught on fire because, unknown to me,
a spark escaped from the firebox and landed in a small pile of wood
about 4 feet from the kiln.
I finished the firing, cleaned up and checked everything and went to
the house to shower. An hour later, the roof was on fire - that small
smoldering spark finally ignited the wood, which caused the flames
to jump up to the roof structure and spread to the whole shed.
My shed is now 100% steel.
If you are worried about the joists over the kiln, I recommend hanging
heat shields (metal roofing sheets) a few inches below the rafters. I
would also install vertical heat shields on the rafters close to the
chimney. Coatings on the joists (no matter what) would not be nearly
as effective. I wish I could have advised you a month earlier, before
you built the shed.
David Hendley
I don't know nothin' but the blues, cobalt that is.
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
From:
To:
Sent: Wednesday, August 17, 2005 9:44 AM
Subject: another kiln shed safety question
> Ok, so now I'm worried...
>
> Several posts have addressed enclosed buildings, wooden and
> otherwise...however I haven't come across anything concerning "lean to"
> type sheds without walls. I have a 60 cu ft bourry box wood kiln which is
> about 6 months old. We had previously been covering it with a very large
> and elaborate tarp system. We finally built a roof over the kiln about a
> month ago, but have not fired since then. This roof is 24 x 16, with wood
> 2x10's as joists, set on wood 4x6 posts, with sheet metal roofing. The
> bottom edge of the joists are about 4 feet above the exterior of the kiln
> arch, and the joists around the chimney are around 3 feet away from the
> bricks. There are no walls on this structure...meaning that it is open to
> wind, breeze, etc...it basically just keeps the kiln and our wood dry when
> it rains or snows. Given the discussion of the importance of air
> circulation, I think we are in good shape in that regard. My worry at this
> point is the proximity of the wooden joists above the kiln. Does anyone
> else think this would be a problem? My arch by the way is 4.5 inches of
> hard brick, covered with fiber blanket and then a layer of castable. If it
> does seem like the roof is too close to the kiln, what about using some
> sort of coating on the joists? I remember a post about something of this
> sort earlier. I also recall hearing about Nils Lou using ITC to cover a
> plywood sheet that was placed in the door of his wood kiln while the door
> was repaired during a firing...what about spraying the joists with ITC? Is
> that overkill? Any help would be great.
>
> Thanks,
>
> Andy Casto
Kurt Wild on wed 17 aug 05
Andy Casto wrote:
..................
roof is 24 x 16, with wood
2x10's as joists, set on wood 4x6 posts, with sheet metal roofing. The
bottom edge of the joists are about 4 feet above the exterior of the kiln
arch, and the joists around the chimney are around 3 feet away from the
bricks. ..........................
My arch by the way is 4.5 inches of
hard brick, covered with fiber blanket and then a layer of castable. If it
does seem like the roof is too close to the kiln,
Andy:
In my opinion you are absolutely OK with what you have. i doubt very much
that spraying with ITC is needed and besides you don't need that expense.
Look at photo #40 in the third album (Hay Creek Flatagama) at
http://kurtwild.myphotoalbum.com/
It sound like you are in a similar situation as the Flatagama and we feel
we are in good shape there.
Kurt
River Falls, WI
Kurt
John Baymore on wed 17 aug 05
Andy,
Hi. With four feet of clearance above the kiln arch and totally open
sides, the general joists are likely just fine. A bit depends on the
design o the kiln...... 4 1/2" of hard brink is not really insulating....
so HOW MUCH fiber and how MUCH of what kind of castable is on top of the
brick? Also do you have really large "blow holes" on the top of the arch
or anything?
Generally though unless the fibwer and castable is a "skin coating"
......... probably OK.
Three feet of clearance to the chimney refractories again sounds fine...
but again the exact design matters a bit. Is the chimeny brick at the
roof penetration point? What KIND of brick? How thick? Do you fire a
single day cycle... or for a week at a time? Those things CAN affect the
answer a bit.
I've perssonally seen wood at a distance of five feet from the chimney
ignite from the radiant heat from a non-insulated steel drum metal wood
kiln chimney (put in by someone else) fired on a single day cycle .
Then there is the "pocket" that forms inside that "box" of wood joists
surrounding the chimney. Is the chimney flashed tight to the roof
decking? The best solution is to have the flashing on the chimney
separate from the flashing on the decking.... forming a rainproof channel
for upward airflow along the chimney and up and out. Hard to explain with
words .
Hot air rising off the hot chimney exterior walls is caught in the pocket
otherwise....... and it can get very hot there ....particualry when you
combine that with the sun beating down on the roof decking. Eventually
that heat lowers the ignition point of the wood there.
Hope these thoughts help. Probably... you are just fine.
best,
...............john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
JBaymore@compuserve.com
http://www.JohnBaymore.com
"Please use compuserve address for any direct communications."
marianne kuiper milks on wed 17 aug 05
Hey, I asked that question but, to my knowledge, did
not get a satisfactory answer from anyone. I have
prety much the same situatyion you described (above
the kiln) and would love to feel assured before I fire
my 1st load. (My husband's Miata Special Edition is in
the adjoining garage...need I say more?) Please keep
asking, I'll keep searching.
Good luck. Marianne
PS I may have had an answer, but was aty clay
sleep-over camp :) and missed/threw out hundreds of
Clayart stuffs when I came home.
--- Andrew_M_Casto@PROGRESSIVE.COM wrote:
> Ok, so now I'm worried...
>
> Several posts have addressed enclosed buildings,
> wooden and
> otherwise...however I haven't come across anything
> concerning "lean to"
> type sheds without walls. I have a 60 cu ft bourry
> box wood kiln which is
> about 6 months old. We had previously been covering
> it with a very large
> and elaborate tarp system. We finally built a roof
> over the kiln about a
> month ago, but have not fired since then. This roof
> is 24 x 16, with wood
> 2x10's as joists, set on wood 4x6 posts, with sheet
> metal roofing. The
> bottom edge of the joists are about 4 feet above the
> exterior of the kiln
> arch, and the joists around the chimney are around 3
> feet away from the
> bricks. There are no walls on this
> structure...meaning that it is open to
> wind, breeze, etc...it basically just keeps the kiln
> and our wood dry when
> it rains or snows. Given the discussion of the
> importance of air
> circulation, I think we are in good shape in that
> regard. My worry at this
> point is the proximity of the wooden joists above
> the kiln. Does anyone
> else think this would be a problem? My arch by the
> way is 4.5 inches of
> hard brick, covered with fiber blanket and then a
> layer of castable. If it
> does seem like the roof is too close to the kiln,
> what about using some
> sort of coating on the joists? I remember a post
> about something of this
> sort earlier. I also recall hearing about Nils Lou
> using ITC to cover a
> plywood sheet that was placed in the door of his
> wood kiln while the door
> was repaired during a firing...what about spraying
> the joists with ITC? Is
> that overkill? Any help would be great.
>
> Thanks,
>
> Andy Casto
>
>
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>
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>
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Gordon Ward on thu 18 aug 05
Tom,
Excellent post. Thank you. This is why I am now a proponent of
ventilation hoods on indoor gas kilns. They remove heat from the
source and shield the ceiling area at the same time. Making your
entire kiln room function as a vent hood just isn't as good.
Gordon
On Aug 17, 2005, at 6:18 PM, Tom at Hutchtel.net wrote:
> If you're going to be even
> partially in the business of making pots, cover yourself and do things
> smart. Saving money on this kind of safety is well spent. Think
> about what
> you're going thru to protect yourself from a little silica or other
> chems.
> Go through the same effort on the fire issue. If you have questions,
> get to
> a pro...not this list, including me.
>
> Tom Wirt
> Hutchinson, MN
Snail Scott on thu 18 aug 05
At 10:44 AM 8/17/2005 -0400, you wrote:
>Ok, so now I'm worried...
>
>Several posts have addressed enclosed buildings, wooden and
>otherwise...however I haven't come across anything concerning "lean to"
>type sheds without walls.
I had a lean-to kiln shed a few years ago when
I was living in Santa Fe. Since we were on the
'unfashionable' end of town, no one cared what
I built. I used Liquid Nails to glue ledger
boards to the stuccoed adobe walls, where they
made a 'L' shape at the back of the house.
I attached the wood structure to these, and
covered it with salvaged mobile-home metal
siding. The roof angled down from just below the
parapet (8' up) to about 4' above the ground on
one side, and just above head height on the
other side. Left the upper end uncovered like a
teepee smoke hole, about 8" wide and 4' across
(the width of the lean-to.) I figured the steep
rake of the roof would help the heat move up and
out, and all the rafters ran up toward the high
end (no cross joists; relied on the ribbed
texture of the siding for rigidity) so no
'pockets' to trap hot air. I nailed tarps to
the bottom edges, rolled up for firing, staked
down when not in use. There was only about 8"
of clearance around the kilns with the walls
rolled down, but since half the walls were
adobe and the other half rolled up, that was
fine. No reason to make the shed any bigger than
the kiln - not even enough room for me. No need.
Simple and almost free, and very little chance
for heat build-up. The cheap tarps lasted only
about a season each, but were easy to replace.
(Adobe - the ultimate fireproofing!)
These were electric kilns, though, and the
radiant heat aganst the rafters was less than it
would be for most fuel kilns. Can you panel the
underside of the wood with more metal roofing,
leaving an air gap? A little shielding goes a
long way, with radiant heat.
-Snail
Snail Scott on fri 19 aug 05
Marianne - Here's that e-mail. I don't think it's
responding to one of yours, but here it is anyway.
It's about lean-to sheds:
>Date: Thu, 18 Aug 2005 12:08:29 -0500
>To: Clayart
>From: Snail Scott
>Subject: Re: another kiln shed safety question
>In-Reply-To:
>References:
>
>At 10:44 AM 8/17/2005 -0400, you wrote:
>>Ok, so now I'm worried...
>>
>>Several posts have addressed enclosed buildings, wooden and
>>otherwise...however I haven't come across anything concerning "lean to"
>>type sheds without walls.
>
>
>I had a lean-to kiln shed a few years ago when
>I was living in Santa Fe. Since we were on the
>'unfashionable' end of town, no one cared what
>I built. I used Liquid Nails to glue ledger
>boards to the stuccoed adobe walls, where they
>made a 'L' shape at the back of the house.
>I attached the wood structure to these, and
>covered it with salvaged mobile-home metal
>siding. The roof angled down from just below the
>parapet (8' up) to about 4' above the ground on
>one side, and just above head height on the
>other side. Left the upper end uncovered like a
>teepee smoke hole, about 8" wide and 4' across
>(the width of the lean-to.) I figured the steep
>rake of the roof would help the heat move up and
>out, and all the rafters ran up toward the high
>end (no cross joists; relied on the ribbed
>texture of the siding for rigidity) so no
>'pockets' to trap hot air. I nailed tarps to
>the bottom edges, rolled up for firing, staked
>down when not in use. There was only about 8"
>of clearance around the kilns with the walls
>rolled down, but since half the walls were
>adobe and the other half rolled up, that was
>fine. No reason to make the shed any bigger than
>the kiln - not even enough room for me. No need.
>
>Simple and almost free, and very little chance
>for heat build-up. The cheap tarps lasted only
>about a season each, but were easy to replace.
>
>(Adobe - the ultimate fireproofing!)
>
>These were electric kilns, though, and the
>radiant heat aganst the rafters was less than it
>would be for most fuel kilns. Can you panel the
>underside of the wood with more metal roofing,
>leaving an air gap? A little shielding goes a
>long way, with radiant heat.
>
>
> -Snail
>
>
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