Preventing Ice Dams
Hey, I have a 1.5 story home (second floor is finished attic space) with a couple dormers and a couple valleys. Half the house is 2×6 rafters with what looks like r-15 foil faced fiberglass insulation (foil face down) with a ventilation gap above insulation venting from the attic under eaves space. The other newer half of the house is 2×6 rafters with r-19 fiberglass and I don’t believe there is an adequate ventilation space above fiberglass. I know what kind of insulation there is in the newer half because there was a leak from a leaky ridge vent and I tore out some drywall in a closet.
Bottom line, I don’t want to/can’t fur down and insulate because of lack of head room. My roof is in good condition (there’s a spot in attic under eaves I’m keeping an eye on to see if it leaks, there is evidence of past leaking) except for the low quality ridge vent that I had to glue down all the exposed nail heads. I haven’t spent a fukl winter in this house yet but I believe this roof if very vulnerable to ice dams. My utilities aren’t that high so I’m hesitant to spend all the money to insulate externally but I do want to prevent ice dams. A bonus would also be to keep rafters at more constant temp because I have some nail popping on ceiling drywall.
Would re-roofing and adding better ventilation solve the ice dams?
I’ve considered leaving existing decking and building up 2 inches and re-decking and adding a ice and water shield to have a major first line of defense against it.
Cathedral style roofs are tricky.
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