Start with a Bulletproof Perimeter
Eaves and roof-to-wall joints are the most common leak points in finished attics. Sequence drip edge over ice-and-water shield at eaves, then underlayment laps correctly up-slope; at sidewalls and dormer cheeks, use step flashing layered with WRB counterflashing, never face-sealed caulk alone. Extend self-adhered membrane at valleys and around penetrations, and keep fasteners out of the critical water path.
Ice-Dam Defense
Ice dams are a symptom of heat loss. Tighten the air barrier at top plates, skylight shafts, and knee walls; add continuous insulation to keep the roof deck warm and even. Where vented designs are used, maintain unobstructed soffit-to-ridge airflow with rigid baffles through every bay—including around dormers—and keep insulation from blocking intakes.
Interior Safeguards
Inside, specify insulated attic hatches with compression gaskets, box and gasket light fixtures (IC/AT), and insulate/air-seal skylight returns. In wet areas, carry bonded waterproofing membranes beyond splash zones and vent baths directly outdoors with insulated, smooth duct.
For a step-by-step edge detailing checklist tailored to sloped ceilings, explore our NYC attic remodeling waterproofing & moisture control resource.