Last updated: 2026-11-04 by Ted Sellers, Owner
What Is a Steep-Slope Asphalt Roofing System?
Quick answer: A steep-slope asphalt roof is a layered system designed to shed water rather than hold it. The shingles are only the visible surface; long-term performance also depends on the roof deck, underlayment, ice-and-water protection, flashing, ventilation, starter strips, fasteners, and ridge caps.
Core Parts of an Asphalt Shingle Roof
- Roof deck: The solid wood surface that supports the complete roofing assembly.
- Underlayment: A secondary water-shedding layer beneath the shingles.
- Ice-and-water protection: Extra protection at eaves, valleys, and other vulnerable areas.
- Flashing: Metal or approved membrane details around walls, chimneys, valleys, and penetrations.
- Shingles and starter course: The primary weather surface, installed in an offset pattern specified by the manufacturer.
- Ventilation: Balanced intake and exhaust ventilation that helps manage attic heat and moisture.
Why Installation Details Matter
Most premature asphalt-roof problems begin at transitions: eaves, valleys, sidewalls, roof penetrations, and ventilation openings. Correct fastening, shingle alignment, flashing integration, and manufacturer-approved materials are more important than appearance alone. Minnesota roofs also need careful planning for wind, freeze-thaw cycles, snow, and ice dams.
Before approving a roof replacement, ask for a written scope identifying the shingle system, underlayment, flashing work, ventilation plan, deck-repair allowance, cleanup, and warranty requirements.
Related Roofing Services
Need a roof inspection in Saint Paul or the Twin Cities? Call Sellers Roofing Company at +1-651-703-2336 or schedule a free estimate. We are a black-owned, NMSDC-certified MBE roofing contractor with 9+ years experience.
