With great interest, we all watched the major snow events on the news this past week.
Buffalo got nailed with that powerful lake-effect snow engine. Over eight feet of snow recorded in some places in just a couple of days.
And when temperatures warmed immediately after the snow, there was a frenzy of activity to get all the snow off the roofs.
Had to chuckle when reading one of the on-line MSN-news articles about the urgency to shovel the snow off roofs.
There had already been a number of building collapses, which is not the funny part… what was funny was how the article talked about the Buffalo area building codes requiring such a “huge” roof snow load design of 50 pounds a square foot.
As taken straight off the article:
“Even for the Buffalo area—one of the snowiest and hardiest places in America—this was one for the history books.
“The three-day total is close to the nearly 8 feet that the region typically gets over an entire year.
“Because the Buffalo area is so snowy, building codes require homes and businesses to be able to handle up to 50 pounds per square foot on their roofs, which would be about as heavy as a slab of concrete 4 inches thick, according to Mark Bajorek, a structural engineer.
“As anyone who has ever shoveled snow knows, its weight depends in part on how wet or fluffy it is, not just on how deep it is. But Bajorek said some buildings may be close to that limit now, with more precipitation on the way.”
The “50 pounds a square foot” is what is funny.
The minimum requirement in the Old Forge / Town of Webb is about 94 pounds a square foot. That’s in the lower elevations near Okara Lakes and McKeever.
Some areas in the town near Big Moose Lake, Twitchell Lake and in the northern most part of the town, north of Stillwater Reservoir, are well over 100 pounds a square foot.
Both Buffalo and Town of Webb have the exact same building codes, same books, same state laws, same everything.
It’s all part of the New York State Uniform Fire Prevention and Building Code.
As far as snow load requirements, the state is broken into regions by a map as part of the overall code.
The Town of Webb is in the highest snow load region, which is a minimum of 80 pounds a square foot plus two pounds for every 100 feet above 1,000 in elevation.
All too often the extra two pounds a square foot is missed by designers, architects, engineers and even contractors when looking at the snow load map, which shows a maximum of 80.
You really need to read the code, completely, because that part about the extra is in the “fine print.”
This could be one of those parts of the code that clearly does not take into account those rare, but well known, events like what Lake Effect Snow can bring.
Buffalo’s average annual snow fall is well below what the Town of Webb experiences.
That doesn’t mean that a structure shouldn’t be designed for what it may be subjected to.
When you have an 8 foot snowfall in two days, even if that is almost the normal yearly average, that creates a lot of weight all at once.
That kind of weight can certainly test any structure.
Some other factors of roof structural stability that many people don’t think about are the unbalanced snow load and all the components of the structure that hold the roof system up.
An unbalanced snow load can easily be created, especially like what just happened in Buffalo, by having one side of the roof be blown almost clear of snow only to have all that snow plus more be draft over to the opposite side of the roof.
No weight on one side and 10 feet on the other. That creates twisting and racking forces that are profound.
Compound that with 50, 60, 70 mph winds, and your structure better be built right and properly braced.
Being built right includes all the walls, beams, window & door headers, bracing and everything that holds up the roof system.
It all becomes critical when there is that epic event.
If Old Forge got 8 feet of snow overnight, a good book, the fireplace, and a blanket would be a new best friend for a few days.
Actually doesn’t sound too awful, does it? Worry about the driveway later.