roof only leaks when snow melts

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  #1  
Old 02-24-05, 06:06 PM
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george maxtor
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roof only leaks when snow melts

i have a single story addition with a roof that has very little pitch. it butts up against the eave of a two story house. i felt that it was leaking because it was roofed as two seperate roofs. the water would come off the two story house and onto the addition faster then it could get off the addition. this would cause the water to back up under the eave and get under the addition's roof.

this summer i roofed it and made the new roof one roof. no gap at the eave.

that worked. had several heavy rains in the fall and i had no leaks.

here is my new problem.

the roof leaked a few days after a foot of snow had fallen. it was warm enough for the snow to melt during the day, but it would drop below freezeing at night.
when i checked the roof i saw all the snow had fallen off the two story roof and landed on the addition.

i now belive an ice dam formed on the edge of the addition and the melting snow couldnt get off the roof.

here is my question.

what would be the best way to solve this ? im thinking of an ice melting roof cord. would that be a good idea ? im thinking if i can keep the ice from forming at the edge of the addition, the melting snow wont back up.

i live near the connecticut coast. near New Haven.

thanks.
 
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  #2  
Old 02-24-05, 08:07 PM
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low pitch

If the low pitched roof has conventional shingles, there's not much that can

be done to stop roof leaks during periods of ice/snow melt. Generally, if the

roof has a 3/12 or less pitch, you should use rolled roofing or a sngle ply

system. You would need to strip the shingles off first.
 
  #3  
Old 02-24-05, 08:39 PM
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george maxtor
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i dont know exactly how much pitch it has, and i cant check right now because it is dark and snowing, but i know its more then 3 1/2 ". i would guess 8". i know its 12' wide and it drops a row and a half of siding shingles in that 12'.

it had roll roofing on the addition and shingles on the two story roof. i took that off, it was leaking so bad the wood was rotting, and i shingled both roofs as if they were one roof.
thanks for the suggestion, but i am not taking the roof off again and going back to the roll roofing. i belive the roll roofing was the problem. i fixed the leaking when it rained problem, now i just need a way to fix the leaking when the snow melts problem.
 
  #4  
Old 02-26-05, 04:22 AM
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Sounds like your lower roof could use some more insulation/ventillation. Heat tape will solve your problem. Go to your local roofing materials distributor...he has many lengths ready to go. The kit will include the clips used to hang the wire on the asphalt shingles.
Jim
 
  #5  
Old 02-26-05, 05:11 AM
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One of the more common leaking situations I've run accross is shingles installed on a pitch lower than 4/12. There's way way to predict when or if these roofs will leak, but it certainly has a good potential for leaking. The water simply migrates sideways, and will actually run uphill a bit once it's trapped beteen the shingles. 90lb. rolled roofing or an "ice&water" membrane should have been installed prior to shingling. I agree that 90lb. rolled roofing is not worth much as a roof, but it is fine and good for valleys, starter strips, extra underlayment, etc.

If your roof leaks now, in snow, chances are good it will eventually start to leak during rain. Leaks may tend to show up during certain weather conditions but generally start to leak in all.
 
  #6  
Old 02-26-05, 11:57 PM
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george maxtor
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i installed GAF weatherwatch on the entire lower roof and about 3' up the two story roof. GAF said i had to add ventilation if i covered the entire roof. i added ridge vents to the two story roof and plan on adding soffit vents to the lower roof this summer.

there is very little insulation in the lower roof. it was buit in the 1960's and about half of the original insulation was destroyed by the leaking. i plan to increase the insulation in the summer also.

my wood stove is in the room next to the addition with the leak, so a lot of heat from the stove is going through that roof right now.

what do you mean by "heat tape" ? is that the same as the ice melt cables ? you lay it on the roof and electricity heats it and melts the snow ?

do you think the lack of insulation and ventilation might be my only problem ? should i try adding the insulation and soffit vents first ?

i do not want to go back to roll roofing. this is the best this roof has been in forty years. this was my fathers house and it has leaked my whole life. it has been repaired and replaced by pros many times, and it would leak as soon as they were done. they all used roll roofing. half of the water and snow from the house lands on this roof.

thanks everyone.
 
  #7  
Old 02-27-05, 06:54 AM
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You mentioned it leaking at the "edge". Dp you mean the drip edge of the lower-pitched area? I don't know if that's what you mean. BUT, if it is, the Weatherwatch won't necessarily prevent it from leaking at the drip edge unless it's tied-in with a wider {like 12 inches wide or more} metal drip edge flashing. The wide metal flashing would be installed
first , then the membrane would lay on top, sticking to it, then you shingles.

As for the heat tape mentioned, it is the gutter cable made for exterior use. It does work in areas I'm familar with.
 
  #8  
Old 02-27-05, 08:48 AM
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george maxtor
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i do not belive it is leaking at the drip edge of the lower pitch roof. i believe an ice dam forms at that edge, causeing the water to back up under the shingles.

it used to leak ,when it had roll roofing, at the edge where the lower pitch roof met the steep pitch ,higher, two story roof. i belived the water couldnt get off the low roof fast enough, while a lot more water was coming down the pitched roof, and the water just sat there like a whirlpool in a river.
by useing shingles, i was able to get rid of the gap under the eave of the high roof. i flashed , weatherwatched, tar papered and shingled the joint between the low roof and the high roof. the pros always ran the roll roofing under the eave. now with shingles, i got rid of that pocket under the eave.

it is now leaking at the same place it used to leak. where the low roof meets the high roof. once the water backs up to the high roof, it has nowhere to go. i believe thats why it doesnt leak when it rains, it doesnt leak when the snow melts, but it does leak when a lot of snow is melting and it freezes at night.

thanks
 
  #9  
Old 02-27-05, 10:19 AM
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Leaks occuring from a pitch change are not uncommon. But if it's done in the right fashion, with sufficient redundancy built in, it shouldn't leak, even with creeping ice mounds of snow, etc. I think it's one of those things which has to be seen to diagnose. To bad you can't post a few pictures of the area involved.
 
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