Compare complete roof systems, not just the labels "metal" and "asphalt." A useful choice starts with the roof's slope, condition, access, budget and the details around valleys, chimneys and skylights. This guide gives Seattle and Eastside homeowners a checklist for comparing two written proposals.
Quick Comparison: What to Ask for in Each Quote
| Decision | Asphalt Shingles | Metal Roofing |
|---|---|---|
| Exact product | Shingle line, accessories and color | Panel profile, metal, coating and color |
| Installation | Deck condition, underlayment, fastening and ventilation | Deck condition, underlayment, clips or fasteners and flashing details |
| Appearance | Compare samples for texture and color | Compare samples for profile, seams and finish |
| Maintenance | Ask about debris, moss and damaged shingles | Ask about debris, coatings, flashings and fasteners |
| Warranty | Read the selected system's material and workmanship terms | Read the selected system's finish, material and workmanship terms |
| Total price | Itemized installed scope, allowances and exclusions | The same itemized scope for a fair comparison |
Compare the Installed Cost on the Same Roof
Start with the same measured roof area and tear-off assumption for both bids. Then compare decking repairs, underlayment, ventilation, flashing, disposal and access. A lower material price does not tell you whether the proposals include the same work.
Our Seattle roof replacement cost guide includes planning ranges and a scope checklist. Use a property-specific estimate for a purchase decision. For a lifetime-cost comparison, write down the assumptions about maintenance, future repairs, financing and how long you intend to own the home; do not treat a predicted service life as guaranteed.
Check Performance for the Named Product
Ask for the actual product documents and installation requirements. Wind and fire classifications, impact resistance and warranties need to match the proposed product and assembly. A generic wind-speed figure for every metal roof or every shingle roof is not a reliable comparison.
CertainTeed's roofing guide explains shingle features and the distinction between product and workmanship coverage. Ask which components and installation conditions apply to the system in your quote. A warranty period is not a forecast of how long your particular roof will last.
Plan for Moisture, Debris and Maintenance
Discuss the conditions around your home: tree cover, leaf accumulation, drainage paths, roof penetrations and access for maintenance. Ask what inspection schedule and cleaning methods the manufacturer recommends. Neither material makes flashings, gutters or roof details maintenance-free.
For asphalt roofs, the Asphalt Roofing Manufacturers Association distinguishes algae discoloration from moss that can affect shingle performance. Moss alone does not establish that a complete roof replacement is necessary. Ask about the roof's condition before choosing treatment, repair or replacement.
Consider Comfort and Appearance
If rain noise matters to you, ask how the proposed assembly addresses it, including the deck and space below. View samples outdoors and check any neighborhood approval requirements before ordering. For metal, ask to see the proposed panel profile and discuss visible surface waviness and flashing details.
Energy performance depends on more than the material name. The Department of Energy's guide to selecting cool roofs (PDF) considers reflectance, climate and building conditions. Ask about the actual finish and your home's insulation and ventilation rather than relying on a blanket percentage savings claim.
Bring These Questions to Your Estimate
- Which exact product and roof assembly are you proposing, and why does it suit this roof?
- What decking repairs are included, and what happens if more damage is exposed?
- How will valleys, chimneys, skylights and wall junctions be flashed?
- What maintenance will I need, and how can it be performed safely?
- Who handles material, finish and workmanship concerns after installation?
- What assumptions, exclusions and payment terms explain the price difference?