The curved ones, on the second page, are mine.
--
John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers
jlarkin att highlandtechnology dott com
Looks like one heck of an ice dam problem.
I don't know of any problems; it does sometimes get noisy in the night, when tons of snow break loose and slide off the roof. The building codes up here specify a snow load of 400 pounds per square foot, and sometimes that's not enough.
But I thought the icicle images were astounding. I still can't figure out how this can happen.
Nice planet we live on.
-- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
400 Lbs??? That's kind of huge considering even Denver is only 90 psf. The problem with ice dams is not roof collapsing but water leakage.
The problem up here, in big-snow years, is decks collapsing or being ripped off the sides of houses.
The roof is metal, and fairly steep, 45 degrees roughly, which is typical up here. I don't see ice dams. We do get the cool slow creep and curl effect, but the curls usually break before they touch the house. We have seen the occasional curved icicle touch a window.
In the winter of 2010-2011, we got 80 feet of snow on the Sierra crest. There was a continuous curve of snow from the roof of our cabin to our neighbor's.
I have seen welded tabs on roofs, like airplane spoilers, on commercial buildings. I guess they keep the snow from sliding off onto customers. Of course, that implies snow removal on the roofs.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Gotta be a wind. Water just won't flow sideways, or even UP, without something to push it.
Was it windy there at some time?
Jon
he problem with ice dams is not roof collapsing but water leakage.
That's ridiculous, it has to be substandard construction. The main reason f or roof collapse is quite simply snow load exceeding the roof rating, but t he roof easily handles 2x rating. The problem is usually the formation of d rifts that causes roof accumulation far in excess of the design worst case snow fall. There were a bunch of roof collapses in the northeast blizzard z ones this year, mostly the commercial flat roofs but quite a lot of cheaply built residential. The problem was the blizzards came in one right after t he other before the first accumulation could melt off or be removed. These owners need to be more proactive and get that existing heavy snow load off their roof when they have a reliable forecast of a second blizzard coming t heir way. Usually things like strange sounds of wood creaking and nails pop ping is a giveaway that the structure is at its limit.
omes/
Way cheaper than the liability payout to even a single person injured by a big chunk of ice falling from height.
Only 45 degrees? That's 12:12. Even here in the South 15:12 is common. In some areas it's required.
We saw a lot of collapsed decks in early 2011. I think it must be wood rot or something, since the houses in our development were all built to code. Some cabins up here have a sloped metal roof that dumps onto a deck: what WERE they thinking?
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
I don't think this was wind. The snow creeps down off the roof and curls at the edge, as the icicles are forming. I still don't entirely understand it; I should arrange a time-lapse camera one year. Not this year, not enough snow.
This guy is the icicle guru:
Hey, this is cool:
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Well, I did say "roughly."
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
If all those cabins are buried in shade all the time, then it takes them forever to dry out.
The so-called code is considered minimally acceptable in the trade, the perfectionists routinely exceed it, the minimalists think of ever more creative ways to fool the clueless inspector.
Metal is best for durability but the seams are NOT water proof. If a seam is submerged, it will leak eventually.
Wow, another blast from the past. Steve Morris and I were reasonably good friends at UBC (1978-81). The two of us and a very smart guy called Ichiro Shinkoda hung out in the Physics Society common room (Hennings 307) and did problem sets. (There were a few others who came sometimes, as well.) Haven't talked to any of them in 30 years, alas.
Steve was big into Pugwash conferences and stuff like that, iirc.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
I've just swapped a couple of emails with him, but I like him. He's fascinated by weird and wonderful visual things.
I really should do the time-lapse icicle thing.
-- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
OK, NOW I got it! The snow creeps down and over the eave. icicles form straight down, just as normal. Then, the mass of ice creeps down more, and rolls over the edge. That swings the icicles inward toward the house. Time lapse would be really cool, you could see the icicles slowly rotate!
Jon
Right, but I don't understand the details.
-- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Plastic flow, which slushy snow-ice can certainly do. I guess it is really just a glacier in miniature.
Jon
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