Robert11 wrote:
Hello,

Live in New England; typical Colonial.
Every few years it seems we get water damage due to "ice dams"

a. exactly what is the mechanism that causes these ?

What conditionsmust be present ?
e.g., temp's at night or during the day, etc. ?

b. We have gutters.
Would it help minimize the possibility of having, if we removed them ?

Any thoughts on this would be most appreciated.

Thanks,
B.


Heat from below melts some snow, and then freezes again. More snow
melts but it cannot run off, so it backs up behind the ice (dam) and
seeps under the shingles. Refreezing under the shingles can also cause
more of a gap, allowing more to run under the roofing. Adequate
ventilation and insulation should keep the attic
cold enough that the bottom layer of snow does not melt. Got soffit
and ridge vents? Do a google on "formula attic ventilation" - I think
it is 1 sq. ft. of vent on top for each 300 sq ft of attic floor area
(not roof area).

Gutters that are plugged up can also cause backup or backsplash - had
that in florida, which caused a little wetting of wall inside.