How to Prevent Ice Dams on Your Roof
A comprehensive guide to protecting your home from ice dam damage during winter
What Are Ice Dams?
Ice dams are ridges of ice that form at the edge of a roof, preventing melting snow from draining properly. This trapped water can back up under shingles and cause significant damage to your roof, walls, ceilings, and insulation.
Causes of Ice Dams
Primary Causes
- Uneven roof surface temperature
- Poor attic insulation
- Inadequate ventilation
- Air leaks from living space
Contributing Factors
- Complex roof designs
- Heavy snowfall
- Fluctuating temperatures
- Clogged gutters
Prevention Methods
Proper Insulation
Maintain consistent attic temperature
- Ensure R-50 or higher insulation value
- Seal all air leaks from living space
- Insulate and seal attic hatches
Adequate Ventilation
Keep air flowing through the attic
- Install sufficient roof vents
- Keep soffit vents clear
- Maintain proper intake-to-exhaust ratio
Heat Cable Installation
For persistent problem areas
- Install UL-listed heat cables
- Create zigzag pattern on roof edge
- Ensure proper drainage path
Proper Insulation
Proper attic insulation is your first line of defense against ice dams. The goal is to maintain a consistent roof temperature from eave to ridge.
Recommended R-Values
- Minimum R-50 for cold climates
- Even distribution throughout attic
- Special attention to eaves
Air Sealing
- Seal all attic air leaks
- Install proper vapor barriers
- Address common leak points
Ventilation Solutions
Proper Ventilation
- 1 sq ft of ventilation per 150 sq ft of attic space
- 50/50 split between intake and exhaust
- Continuous soffit and ridge vents
Common Issues
- Blocked soffit vents
- Insufficient ventilation
- Improper vent placement
Emergency Measures
If Ice Dams Form:
- Remove snow safely: Use a roof rake with wheels to prevent shingle damage
- Create channels: Use calcium chloride ice melt products (never rock salt)
- Professional help: Contact a licensed professional for steam removal
- Warning: Never chip at ice dams or use sharp tools on your roof