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  1. #1
    Join Date
    Dec 2009
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    Central MN
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    Default How much weight can a roof hold?

    Exactly what it says………..I live in central MN and we first got a decent snow fall and then some nasty rain this past wed.-Fri. I am positive the majority of my roof is fine but I have one valley that appears to have about 14”-20” (just from looking from the ground) of snow/frozen mixture.

    I have the traditional asphalt shingles……..would I be doing more harm than good by removing the snow? The roof is only 2 years old.

    Thanks

  2. #2
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    Dec 2009
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    West Michigans gold coast.
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    11,313

    Default

    Quote Originally Posted by scott_l View Post
    Exactly what it says………..I live in central MN and we first got a decent snow fall and then some nasty rain this past wed.-Fri. I am positive the majority of my roof is fine but I have one valley that appears to have about 14”-20” (just from looking from the ground) of snow/frozen mixture.

    I have the traditional asphalt shingles……..would I be doing more harm than good by removing the snow? The roof is only 2 years old.

    Thanks
    It all depends on you truss snow load rating. Is the whole roof system 2 yrs. old or just the shingles? If the trusses are 2 yrs. old than you would of had to gotten a snow load truss diagram from the lumber yard that is engineer approved in order to get a building permit. That is for Michigan. MN seems like it would have the same thing.

  3. #3
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    Dec 2009
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    Ontonagon-Rockland-Mass City
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    Default

    the load your truss was intended to carry plays a big role in that. up in our area, trusses must have a top chord load of 70# (snow load) and the total load of the truss is 90# min. That min requirement drops as you move away from the big snow.

    Last year, our lumber barn in Mass City had 4' from ridge to eave, front to back. The barn is roughly 60x110. I looked up the average weight of a cubic foot of snow. It varies bigtime but it looked like a good average guess is 15lbs per cu/ft.

    Doing the math, that is over 440,000 lbs of snow on that roof!!! I paid about $600 to have it removed...those poor guys worked hard....you cannot toss snow 30' to the eave end, it has to be carried all the way down.

    I was really hoping this warmup would cause the barn to shed the snow...of course it didnt.

    Good luck, better safe than sorry imho.

  4. #4
    Join Date
    Dec 2009
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    clarkston/harrison
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    Default

    The answer to your question depends on alot of factors. I watch my roof on a regular basis during the winter months. The first question is how strong is your roof? Are the studs 16 inches on center? Some modular homes and others may use a larger distance between the studs making for weaker load ratings. Next question to answer is how much more snow will you get, and is your attic well insulated to avoid ice damming? I usually try to keep the bottom 2 feet at the edge of the roof clear to avoid ice damming. If a home is well constructed as my home down state the roof can hold many feet of snow with no issues. A snow rake is a cheap investment to help maintain your roof in the winter season. With many snowy days ahead it is wise to keep a close eye on the snowfalls and totals.

  5. #5
    Join Date
    Dec 2009
    Location
    Central MN
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    Default

    thanks for all the info so far

    the shingles are 2 years old the house itself was built in 1982.

    Got home late last night and noticed it, going pull out the ladder tonight when I get home and getter a better look at it.

  6. #6
    Join Date
    Dec 2009
    Location
    Central MN
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    354

    Default

    Quote Originally Posted by thebluff View Post
    the load your truss was intended to carry plays a big role in that. up in our area, trusses must have a top chord load of 70# (snow load) and the total load of the truss is 90# min. That min requirement drops as you move away from the big snow.

    Last year, our lumber barn in Mass City had 4' from ridge to eave, front to back. The barn is roughly 60x110. I looked up the average weight of a cubic foot of snow. It varies bigtime but it looked like a good average guess is 15lbs per cu/ft.

    Doing the math, that is over 440,000 lbs of snow on that roof!!! I paid about $600 to have it removed...those poor guys worked hard....you cannot toss snow 30' to the eave end, it has to be carried all the way down.

    I was really hoping this warmup would cause the barn to shed the snow...of course it didnt.

    Good luck, better safe than sorry imho.

    holy balls bat man $600.00 to clear that roof........wow those guys had to be really hungry! Any idea how long it took them?

  7. #7
    Join Date
    Dec 2009
    Location
    Phelps, WI
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    6,649

    Default

    When in doubt remove snow is my motto. If your roof is grunting & groaning the snow is the cause. Not a big deal to remove snow shovel or rake just lighten the load & don't scrape.

  8. #8
    Join Date
    Dec 2009
    Location
    Greenland, Mi
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    you wont hurt the roof by shoveling it unless you jam the shovel underneath the shingles, just don't go that deep. I shoveled a section of mine last night and it's no problem. I shoveled mine because of a huge ice damn. I needed to get the ice off as it was preventing water from draining. Without proper insulation and ventilation, water will melt down the roof and freeze on the eves. It can hold water underneath. I removed a lot of ice and than all a sudden the water let loose and was like an open faucet. Must have had a few gallons damned up. It was also coming in the porch ceiling. I turned off the heat in the porch and in the spring I will insulate with blown-in and be sure the ventilation is correct. You could describe the the roof system to a "knowledgeable" person at a yard and get some info on your snow load. As Matt (bluff) said trusses are engineered to a specific load so if you are concerned you might want to check into it.

  9. #9
    Join Date
    Dec 2009
    Location
    Winter wonderland & State with all the fresh water eat your heart out NASH!!
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    641

    Default

    Quote Originally Posted by scott_l View Post
    Exactly what it says………..I live in central MN and we first got a decent snow fall and then some nasty rain this past wed.-Fri. I am positive the majority of my roof is fine but I have one valley that appears to have about 14”-20” (just from looking from the ground) of snow/frozen mixture.

    I have the traditional asphalt shingles……..would I be doing more harm than good by removing the snow? The roof is only 2 years old.

    Thanks
    It's not the shingles you need to worry about...it is the stuff holding the shingles up under them that counts.

    If the majority of your roof is clear then the valley should be fine, even with a good amount on it. Remember that basically 6-10 inches of snow is one inch of rain. But that snow can hold a whole bunch of rain and therein lies the problem. The more rain you get on a deep snow covered roof, the more likely you will have a collapse.

    Just be careful getting the snow off, taking your time means no broken shingles and no trips to the hospital.

    And anyone who builds in snow country should figure on the worst and build accordingly, even if the company says it's okay...they won't be out the money if it all comes down. You will!!!

  10. #10
    Join Date
    Dec 2009
    Location
    Central MN
    Posts
    354

    Default

    Thanks for all the info guys.......I got most of the snow out of the valley using the neighbors roof rake and ladder. There was probably more like 20"-24" of hard snow in there, so I am guessing the weight would not have been a problem. There is still a crust of snow on top of the shingles that I did not remove (I am guessing about 1-2") so no damage there. But I do have a ice dam, I am guessing it's about 5'-6' wide and as far as I can tell about 3" tall. I can get my step ladder right up next to the edge where the ice damb is. Should I just leave it along, put something on it or what. This part of the roof is partly over my porch and partly over my entry way so some heat (from inside) and some not.

    Thanks all!

  11. #11
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    Dec 2009
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    Greenland, Mi
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    I have a metal roof and I half to remove the ice because it will destroy the roof if it gets under the metal, and believe it has happened to many people. looks like a small explosive was set off under the metal. I use a rubber mallet and know the stuff off. I have removed ice off shingles and it does stick much better and will not come off clean like metal does. The thing you need to be concerned about is the ice at the edge of the shingle starting to creep up the underside of the shingle and ultimately entering the living space. Newer homes should have ice and water shield 2 courses up applied directly over the sheeting as not to let the ice contact the sheeting. if it is at the edge you could carefully smack the ice off but don't pound the crap out of it, older roofing can come apart if brittle. Odds are you need to ventilate better and/or insulate when warms temps come back

  12. #12
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    Dec 2009
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    Houghton Lake, MI
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    642

    Default

    Lenny nail that one for sure....Ice dams are a cause from lack of proper ventalation.

  13. #13
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    Dec 2009
    Location
    Bartlett, IL
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    310

    Default

    Without reading all the posts above I would remove as much as possible. The live load in your area is 75lbs - 95lbs psf. which doesn't sound like much but it is.

    To remove the snow take a 3/8 rope and swing/throw it up over the snow and with 2 of you simply slice through the snow from the highest point down making sure you are not infront or under the snow as you cut through it. Getting all the way down to the shingles is not needed.

  14. #14
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    Dec 2009
    Location
    Central MN
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    Default

    Quote Originally Posted by trailshredder View Post
    Lenny nail that one for sure....Ice dams are a cause from lack of proper ventalation.
    I am no expert (after all I am on a snowmobile website asking house questions) but I am not sure ventilation is the big factor in this situation. We started out with a decent snow fall and some pretty strong winds, so I am sure this area filled in with snow from that. We then went out of town for a few days and when we came back our drive way that looked like a skating rink. I talked to the neighbor and he said it rained pretty good for a few hours. And where I am having the problem 3 roof lines basically dump into one area, so I am guessing the combination of the rain and snow has caused my problem. I have been in the house for 7 years and have never had this problem in the past.

    Thanks all

  15. #15
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    Dec 2009
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    Greenland, Mi
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    Default

    you may be correct, especially when it rains in the winter. Regardless of why, an ice damn can cause problems. Typically older homes without roof ventilation and poor insulation are the culprit. When your heat from the living space escapes into the attic excessively, it will melt snow on the roof which in turn will run down the roof till it hits the eve's (over non-heated area) and freeze. The correct amount of insulation will retain the heat in it's proper location. Ventilation will allow the heat loose to exit the attic without melting the snow. A minimum of R-38 in the attic is recommended.

    You very well may be fine with your insulation and ventilation but it cannot hurt to check because if not, you will be dumping money "out the window" so to speak. I would say by what I saw at my house this winter so far that I have severe heat loss and in my attic. My insulation barely covers the 2x6 ceiling joists which is roughly a R-19 (poor) Most houses in da UP are not insulated at all, go figure, we burn wood and heat our houses around 75 degrees easily and you'll see huge ice sickles forming, getting bigger and bigger, sometimes creeping up the roof. It's when it gets under the roof and creeps where the damage occurs

  16. #16
    Join Date
    Dec 2009
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    clarkston/harrison
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    Default

    Lenny is right, still check to see if you have heat loss in that area. The warm air will melt the snow till it gets to a non-insulated part of the roof and freeze. With alot of winter left you may want to expose a small channel to allow water to flow when it begins to melt. Careful chipping at the ice can work but you need to be very careful as you get close to the shingles. Calcium chloride can help soften the ice but I have been told only to use it in an emergency. I have also used a hot water source to melt ice. Hey put this to sleep and get out and ride. See ya on the trails!!!

  17. #17
    Join Date
    Dec 2009
    Location
    Minnesota
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    32

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    I would remove it cuz if its froze on it won't melt off that easy. plus its only going to get more on it as winter goes. whats on there is is wet heavy snow not lighter powdery snow. so 12 inches is heavier than normal

  18. #18

    Default

    Over the last 30 years I've been in the business.
    Minnesota code for snowload has been either 40#/sq ft or 45#
    Far north went to 50# at one time.

    Never 90 that I know of

  19. #19
    Join Date
    Dec 2009
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    Reddick Il.
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    422

    Default

    If trusses you should be good, but in a stick built roof the valley is the weakest part. There are snow rake brooms that look like swim pool net without the net but have a flap of plastic you reach up drop the hoop down and drag under snow and pull it down.

  20. #20
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    Dec 2009
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    Boulder Junction ,WI.
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    Default

    lennys right , many old houses had no insulation, if it snowed alot you put a few more logs on the fire and blew the snow off! most of the roof would be bare and overhang had big ice dam with huge iceleces. alot of oldtimers would put sheetmetal on the overhang! If a house is built right,insulated right,and vented right you should have no ice dams and shouldnt have to shovel your roof! old timers used to worry if it rained on huge snowload because of the extra wieght and would get the roof cleared as soon as possible!

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