There’s some disagreement about this subject here in Colorado.
Three years ago we had a storm that dumped 8 feet (that’s measured feet, we had about 5 feet on the ground). Snow sliding off metal roofs ripped signs off of commercial buildings and deck handrails off homes with roof designs that didn’t route slides above the rail.
I had a disussion yesterday with a broker who is dead set against them. His argument was that the big advantage to expensive metal roofs is that they shed snow easily. Preventers defeats the whole purpose. He went on to point out that snow will slide eventually anyway and preventers just force roof accumulation to build up to unsafe levels before it finally slides. These seem like a valid points, at least under some circumstances.
Seems to me it might depend on site-specific conditions. The roof pitch, temperature of the roof and temperature and nature (stickiness) of the snow all should effect the level of accumulation that will build up before the snow slides.
A shallow pitch with no preventers might be very dangerous if wet snow fell on a frozen metal roof. It could build up to unsafe levels before the roof warmed up and it broke loose. A shallow pitch with preventers might not shed snow at all and then why pay all that money for a metal roof?
A steep roof usually sheds snow at fairly low (safe) levels of accumulation, so no preventers seems better in that situation.
I see them mostly on commercial buildings here but, some upscale homes have them.This one also had a $135,000 audio/visual setup. The $45,000 driveway was nice too.
the issue over snow deflectors is a complex one as they are there to serve 2 purposes dependent on roof type.
Slate/Tile roofs: they were originally installed on these roofs to prevent tiles or thier fasteners being dislodge by large snow loads sliding down the roof.
Steel roofs: the only real application for them on steel roofs is to protect pedestrian access areas from people being injured by avalaches from the roof.
the isuue really becomes one of roofing type, and liabilities.
Don’t you know that these glycol filled exterior sprinkler heads are to protect this roof of fiberglass imitation slate from the ambers from the Winter wood burning stoves up in Wisconsin??
Those are either metal or rubber shingles. I usually have to get up close and feel them to be absolutely sure.
I had a home in Truckee, Ca. and we could get substantial snow falls. When we were building our home I wanted to a metal roof but my builder talk me out of it for liability reasons. His feeling was that not only was the sliding snow a people hazard but the falling snow could compromise the side walls or break windows.
Last December at one point they had 13 ft of snow on the ground. The only saving grace was that it was a very dry snow.
