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  • #31
    Down here in the land of Bless your Heart and Barbecue, I built my shop with a 4-12 pitch.
    Balloon frame, I have 9 foot ceilings in the shop proper, and an attic with 4 foot knee walls
    and 7 foot under the collar ties. The high bay has no attic, and 15' under the collar ties.
    A traditional yankee land roof really would not have gained me anything, the way I layed
    things out. A side note, I would never do a tin roof again. Can't walk on it without denting
    it and it is slippery as heII. Asphalt shingles are way better and easier in my book.
    It was a happy day when I sold my snow blower, I will tell you that. Yall's don't need no
    heat tape 'round these parts ! ! ! ! !

    --Doozer

    DZER

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    • #32
      Living in Green Bay gives one a real perspective of Winter and Ice Some of the comments made are "generally" applicable and others may not.
      Heat cables burn out when they are allowed to touch each other, so you must use separators. These are aluminum strips 1/32 x 1/2" wide and maybe 2 inches long that are rolled
      on each end holding the cables apart, but parallel to each other and the aluminum acts as a conveyor of heat AND water between the cables . I have used cables here in Green Bay for 30 years and have 12 inches of insulation in the ceilings , but we get - 20 F temps and weeks where 10 degrees is a hot spell ......back to the cables. I have never had a burned out cable but I do replace them after 12 to 15 years because having a failure in winter is a real no-no. The cables only are effective from 20 to 40 F IMHO -----They shut off when it gets warm and when it gets too cold , there isn't enough heat. at 3 watts per per foot which is about 10 BTU per foot . My House was L shaped by design but I had the builder add my shop, and it became U shaped.
      Two things work creating Ice Dams
      The low angle of the sun means part of my roofs never see sunlight in the winter and the builder put the high efficiency furnace exhaust in the U , which means a heat + humidity source adding to the problem. I have 160 feet of cable (100 +60) and "W"s on the roof 3 feet high and a Valley . I start the cable 4 to 5 feet underground (drain field) ( 40 inch normal frost line ) on both down down spouts and the longer cable does the W's and the shorter is the valley and the gutter . The center of the "U" has two cables side by side , so water can go to either downspout.
      This is Green Bay, so the rubber membrane covers 6 feet from the gutter besides having felt under the asphalt shingles . When my roof was redone a few years ago, I gave the roofer a dozen strips of aluminum 1/32 x 1" x 12 inches , and had him nail it under a course of shingles 3 feet up and 3 feet apart with a 2 inch exposure. Then I did my W's and used the strip by rolling then up a bit into C's .. before that, the cables came with shingle clips, and they eventually break or shred the bottoms of the shingles from expansion and contraction and you loose the W .

      Hope this helps
      Rich
      Green Bay, WI

      Comment


      • #33
        Originally posted by nickel-city-fab View Post
        The only roof that snow "just slides off" is a copper-plated church spire. In my part of the world, (Buffalo NY area) we are known for our snow, and the building codes all specify how a roof must be done to withstand the weight. Same for the depth of foundations, the legal minimum here is 5 feet, because that's how far the ground freezes.
        When my uncle re-roofed his house he put a 3' aluminum ice slide all the way around the house and no gutters. The shingles start at the top edge of the ice slide, That has worked out pretty well.

        JL...........

        Comment


        • #34
          Originally posted by Rich Carlstedt View Post
          Living in Green Bay gives one a real perspective of Winter and Ice Some of the comments made are "generally" applicable and others may not.
          Heat cables burn out when they are allowed to touch each other, so you must use separators. These are aluminum strips 1/32 x 1/2" wide and maybe 2 inches long that are rolled
          on each end holding the cables apart, but parallel to each other and the aluminum acts as a conveyor of heat AND water between the cables . I have used cables here in Green Bay for 30 years and have 12 inches of insulation in the ceilings , but we get - 20 F temps and weeks where 10 degrees is a hot spell ......back to the cables. I have never had a burned out cable but I do replace them after 12 to 15 years because having a failure in winter is a real no-no. The cables only are effective from 20 to 40 F IMHO -----They shut off when it gets warm and when it gets too cold , there isn't enough heat. at 3 watts per per foot which is about 10 BTU per foot . My House was L shaped by design but I had the builder add my shop, and it became U shaped.
          Two things work creating Ice Dams
          The low angle of the sun means part of my roofs never see sunlight in the winter and the builder put the high efficiency furnace exhaust in the U , which means a heat + humidity source adding to the problem. I have 160 feet of cable (100 +60) and "W"s on the roof 3 feet high and a Valley . I start the cable 4 to 5 feet underground (drain field) ( 40 inch normal frost line ) on both down down spouts and the longer cable does the W's and the shorter is the valley and the gutter . The center of the "U" has two cables side by side , so water can go to either downspout.
          This is Green Bay, so the rubber membrane covers 6 feet from the gutter besides having felt under the asphalt shingles . When my roof was redone a few years ago, I gave the roofer a dozen strips of aluminum 1/32 x 1" x 12 inches , and had him nail it under a course of shingles 3 feet up and 3 feet apart with a 2 inch exposure. Then I did my W's and used the strip by rolling then up a bit into C's .. before that, the cables came with shingle clips, and they eventually break or shred the bottoms of the shingles from expansion and contraction and you loose the W .

          Hope this helps
          Rich
          I don't get the severe cold here that you get. I think the lowest so far this year has been 9 degrees. Can't remember the last time the temps dipped below zero. (global warming you know) My roof is a 12-4 pitch, I guess that's considered low angle. But this water backup / ice dam doesn't happen every year. Ive gone several years with no problems. It all depends on the weather and the amount of snow we get. This is why I never put in any permanent type of heat wires.
          I like the idea that GadgetBuilder mentioned in post #21. I think for next year I'm going to try that approach or at least have it on standby and ready to toss up on the roof if the weather forcast predicts a significant amount of snow is coming.

          But, I have a unique problem hear as I have a heat source close to the outer walls in a couple spots that I can't really do much about. Thats the big contributing factor to my ice buildup.

          JL...........


          Comment


          • #35
            I used to get bad ice dams above my living room picture window. Single story bungalow, 4-12 shingle roof. Had some pretty bad leakage one year, and replaced the roof the next summer. We laid down 2 rows of ice and water paper across that section, and I added moore vents, and more insulation in that spot, as well as vent the soffit more. Next 2 years were great, but I've got one pretty bad in the same spot again right now. I used to fill a sock with salt and lay it up there to form channels to drain, but don't want to do that with the new shingles. It's only the one spot on my roof that does it. I'm going to give the heat cable on a piece of wood a try. Great suggestion, thanks.

            I used to attribute it to a few things like lack of ventilation, lack of enough insulation, and the electric baseboard being right there. Not sure why one formed there this year, as all those things have been changed, although the heat source for the room is still in the same spot (forced air propane furnace now).

            Comment


            • #36
              Used to have terrible problems with ice dams. 1-1/2 story 12-12 pitch, with a good portion of the upstairs ceiling drywall attached directly to the rafters, so no easy access to most of the insulation. I tried the heat cables but found they caused more problems. Really tore up the shingles where they attached, as once spring came the ice would let go and take the cables with it.

              My ridge vent was often snowed over so I added gable vents. Even tried a fan up there to help but the problem was voids in the insulation and air leaks to the attic. Because of the air leaks, the fan actually made things worse. So, every year it was a battle with heat cords, snow rakes, salt and shovels.

              When it came time to do the shingles, I had them pull the sheeting and remove the blown in insulation and replace with spray foam. It seals air leaks as well as insulates. I also added insulation to the small attic area and sealed the attic access door. Been up there enough and never plan to return!

              Now, no more ice dams and lowered heating requirement. Used to be that anything below 30 degrees F would be low enough to keep the wood stove going, Now, even with the single digit weather we had last week I can't dial down the woodstove enough and have to open the workshop and back porch doors to keep from overheating.

              So, the point of all this blabbing is: I tried everything I could, but heating cables and snow rakes don't fix anything and it remained a losing battle. The only thing that worked in my case was starting over and doing things correctly.
              Last edited by George Bulliss; 02-22-2021, 03:16 PM.
              George
              Traverse City, MI

              Comment


              • #37
                Originally posted by Dan Dubeau View Post
                I used to get bad ice dams above my living room picture window. Single story bungalow, 4-12 shingle roof. Had some pretty bad leakage one year, and replaced the roof the next summer. We laid down 2 rows of ice and water paper across that section, and I added moore vents, and more insulation in that spot, as well as vent the soffit more. Next 2 years were great, but I've got one pretty bad in the same spot again right now. I used to fill a sock with salt and lay it up there to form channels to drain, but don't want to do that with the new shingles. It's only the one spot on my roof that does it. I'm going to give the heat cable on a piece of wood a try. Great suggestion, thanks.

                I used to attribute it to a few things like lack of ventilation, lack of enough insulation, and the electric baseboard being right there. Not sure why one formed there this year, as all those things have been changed, although the heat source for the room is still in the same spot (forced air propane furnace now).
                I doubled up the ice and water too and my gut instinct when the roofer suggested it was no because that only forces the water to backup further and that's almost three feet beyond the inside wall where it will drip. At least with three feet when it backed up and dripped it was on the outside wall of the house. I could see water running down the brick wall from behind the fascia.

                I don't throw salt up there anymore because it's corrosive. It caused my alum. gutters to pin hole. So now I use this Mr. Magic stuff, it doesn't pit the concrete either.

                JL..............

                Comment


                • #38
                  I figured the extra strip of ice and water at the time was a no brainer. So far no leaks over that area, even though there IS a damn there. I only used the salt socks because it's what I had, and knew I was replacing shingles that year anyway. I wouldn't consider it a viable long term solution, for reasons you stated, and many others.

                  Originally posted by George Bulliss View Post
                  So, the point of all this blabbing is: I tried everything I could, but heating cables and snow rakes don't fix anything and it remained a losing battle. The only thing that worked in my case was starting over and doing things correctly.
                  Ya I'm with you. I thought I had the problem licked until this year. Not sure why it did it now, maybe a perfect storm of conditions? who knows. This summer I want to re insulate the attic completely, and hopefully solve this once and for all. Again. Like I already thought I did lol

                  Comment


                  • #39
                    Originally posted by Dan Dubeau View Post
                    I figured the extra strip of ice and water at the time was a no brainer. So far no leaks over that area, even though there IS a damn there. I only used the salt socks because it's what I had, and knew I was replacing shingles that year anyway. I wouldn't consider it a viable long term solution, for reasons you stated, and many others.



                    Ya I'm with you. I thought I had the problem licked until this year. Not sure why it did it now, maybe a perfect storm of conditions? who knows. This summer I want to re insulate the attic completely, and hopefully solve this once and for all. Again. Like I already thought I did lol
                    That's about what it boils down to. Enough snow on the roof, a couple warm days when it starts to melt and then the freeze.

                    JL............

                    Comment


                    • #40
                      Proper insulation makes all the difference in the world. It's not cheap. but the good news is that you only have to do it once, and it pays itself back forever. I need 5 new windows, myself.

                      Comment


                      • #41
                        Originally posted by JoeLee View Post
                        I don't get the severe cold here that you get. I think the lowest so far this year has been 9 degrees. ...........................................
                        But, I have a unique problem hear as I have a heat source close to the outer walls in a couple spots that I can't really do much about.
                        Thats the big contributing factor to my ice buildup. JL...........
                        Not like the -20 we had recently and with windchill, its -35..
                        But you are right Joe , about the heat sources. As I said , they put the furnace vents in the "U" along with the Bathroom Vents as a unwanted heat source.
                        When we replace the furnace this coming summer, I will have them move the furnace vents to another wall and hope that reduces the ice.
                        George mentioned foam insulation...way to go...much more efficient
                        Rich
                        Green Bay, WI

                        Comment


                        • #42
                          Originally posted by JoeLee View Post
                          I don't get the severe cold here that you get. I think the lowest so far this year has been 9 degrees. Can't remember the last time the temps dipped below zero. (global warming you know) My roof is a 12-4 pitch, I guess that's considered low angle. But this water backup / ice dam doesn't happen every year. Ive gone several years with no problems. It all depends on the weather and the amount of snow we get. This is why I never put in any permanent type of heat wires.
                          I like the idea that GadgetBuilder mentioned in post #21. I think for next year I'm going to try that approach or at least have it on standby and ready to toss up on the roof if the weather forcast predicts a significant amount of snow is coming.

                          But, I have a unique problem hear as I have a heat source close to the outer walls in a couple spots that I can't really do much about. Thats the big contributing factor to my ice buildup.

                          JL...........

                          May be able to slip some foam insulation into the spaces between rafters/trusses above the point the dams form. Best way is to use 2" foam with 1x4 screwed to bottom of the rafter to leave an airspace between the foam and sheathing for airflow during the summer.

                          Comment


                          • #43
                            Originally posted by kendall View Post

                            May be able to slip some foam insulation into the spaces between rafters/trusses above the point the dams form. Best way is to use 2" foam with 1x4 screwed to bottom of the rafter to leave an airspace between the foam and sheathing for airflow during the summer.
                            Yes, I've thought of doing that if I can reach the area. AC ducts run parallel to the heat pipes close to the roof line.
                            I have 6" rafters and had thought of putting 4" insulation between them. That would still allow about 2" of air space.

                            JL..............

                            Comment


                            • #44
                              I've had water dipping out of a light fixture over the kitchen counter all night long. I went up and shoveled the snow off the edge of the roof again. The dripping stopped within a few minutes.
                              I still have snow that's knee deep in spots that has to melt and run off. I think I'm going to hit this bad spot with hot water and melt all that ice away.

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                              Same problem in the back of the house but nothing has come in yet. Just a little water running down the outside wall from time to time.

                              Click image for larger version

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                              JL...............

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                              • #45
                                JoeLee---My house looked like the picture you posted. It wasn't uncommon to have three foot of snow on my roof. First big thaw, the ice on the main roof over the house would melt and run down the roof until it got on the 18" of roof that extended beyond the walls of the house. Then it would freeze, creating ice dams The water would back up behind the ice dams and my roof would leak. after trying everything else, I put the heating cables on the edges of my roof in a zig-zag pattern that passed from my eves trough up about 30" above the edge of the roof. They created melted zones around the cable, so any water running down from above would pass thru these melted zones and drip off the edge of the roof. I haven't had any problem since putting the cables up 5 years ago.---Brian
                                Brian Rupnow
                                Design engineer
                                Barrie, Ontario, Canada

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