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Roofing - Ridge Vent on Low- Pitch Roof OK?

My house is about 10 miles north of Boston and is a traditional 1950's style cape with two "doghouse" dormers in the front(normal pitch) and a full shed-dormer (low pitch due to raising roof in the 80's) in the rear. The house has gable-end vents and 2 vents towards the top of the rear dormer. My rear shingles are about 11 years old while the front shingles may be older. The rear roof has 3 ft. of I/W shield. I have no records of any I/W shield on the front. The rear shingles are in good condition while the front shingles are moss-covered in some areas. The front doesn't get much sun while the rear gets plenty of sun.

We've been in the house for 9 years and have had 2 icedam water infiltration issues. One was minor and the cause easily fixed while the other was substantial (2 winters ago) and is the reason I'm considering reroofing my house.

Before I make my decision I was hoping my questions could be answered by other readers on this forum.

1. Should I try to reduce the chance of icedams by adding more venting (ridge vents and channel style soffit vents) or have more I/W shield added to protect against icedams and potential water infiltration? Both?

2. Since I have a flat rear roof how much I/W shield should be installed on the roof?

3. Would covering the entire rear dormer with I/W shield be excessive and could it lead to moisture issues in my attic/wood sheathing potentially causing structural roof issues? Most contractors have recommended 6 ft. of I/W shield at edges and valleys and one guy recommended 9 ft.

4. Most roofers have recommended installing a "shingle-vent II" baffled-style ridge vent to the entire ridge. Due to the low pitch on my rear roof, I'm concerned with water getting inside the ridge vent and causing issues. The rear of my house faces northeast and during nor-easters takes a beating. One contractor thought it could be an issue while others did not. You'll only find out if it's a problem when it's too late. Is the ridge vent necessary with the venting I currently have? Is a ridge-vent recommended based on the pitch of my roof?

5. What about wire ice-melters applied to the roof? Are these safe? Could these help with icedams?

6. Is hand-nailing shingles superior to using nail guns?

I know this is a lot, but my wife and I are going crazy trying to figure out the right thing to do. Any advice would be much appreciated.


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