Quoteby DonP: look forward to some pics of the collapse, it helps to keep those things in mind. I've seen plenty of mill owners wanting to use toothpicks for the span and load they had.
I was at Woodmizer in Maine today, picking up two new drive belts and the office lady (sorry I forgot her name) said Ross was out looking at a sawmill, near Fryburg, Maine that had it's roof collapse on it under heavy snow load over the weekend.......
Check your roof design or shovel/rake/remove the snow from it soon......
Jim Rogers
After I blew out the driveway today I went down to the shop and made a wooden snow rake for the lower roof over the shed. It worked well and all I used was scraps. The handle was a long piece of 1-3/8" ash, the blade was 6" wide spruce reinforced with a 2 x 4 on the back. I reinforced the connection of the handle with a strap of cherry across the top to bridge the point where the handle meets the blade. Then I used steal strap at 45's to the handle and blade. Not real heavy to carry and very effective and won't punch holes in my new steel roof. After it was all said and done the snow load wasn't that much after all. Most insurance up here won't cover snow load on buildings.
1997 in February my father cleaned snow off one of the potato sheds, that night a 20" of heavy wet snow fell on the roof again and collapsed the building. Insurance was no good. The next year the same thing happened to about 40 potato sheds in the area. A lot where old buildings ready to fall down on their own weight. They got a government pay out, and we never got a cent for a well maintained building after we put in our '97 claim. That's government fairness for ya. ::)
Here's a gararge that collapsed here in our county recently:
(https://forestryforum.com/gallery/albums/userpics/13183/colapse.jpg)
What's so rediculous is these are the kinds of store bought- truss "engineered" rafter structures our great building department approves of, but if a guy wants to build a substantial post anf beam structure with his milled lumber it takes an act of congress, and the rest of your life's savings.
I am so sick of this nonsense.. ::)
One year we had a bunch of roof fall in and one old handyman said the reason that the roof fell in was beacuse the builders ran one row of 2x4 down the middle of the trusses instead of several.
The trusses didnt brake but bowed sideways then broke.
I went to one barn and you could see the trusses start to bow and they had only one row of 2x4.
The row that i am talking about is the row that keeps the trusses spaced.
Thanks Alot Mr Mom
That is a good point, the permanent bracing specs get thrown in the back of the truck and get overlooked pretty often.
In long truss webs if the specs called for one line of bracing, and its left out, the web is stressed 4x design allowance under full load. If there were 2 lines of bracing drawn and they are left out the webs get a load 9 times what was intended under full roof load. Those lateral runs also need to be tied off by diagonals as per the design specs so the lateral bracing doesn't just bow everything and fail together.
I'm not saying that is the case here but its something to keep in mind whenever installing trusses, read the sheets that come with it and understand them or call the plant for explanation.
This is a good general description;
http://www.sbcindustry.com/images/publication_images/pbrace.pdf