Neither material wins on its label. Whether metal is worth its price over asphalt shingles depends on the exact system, your local wind and weather, and how long you’ll own the house, so get both bids itemized the same way. “Metal roof” covers exposed-fastener panels, concealed-fastener standing seam and metal shingles. “Asphalt shingles” covers many products with different ratings. Compare two named systems, not two materials.
Compare complete systems
| Question | What to ask for |
|---|---|
| Wind and code | Test reports or approvals for the exact panel or shingle, attachment schedule and edge details |
| Roof shape | How valleys, walls, chimneys, skylights and vents will be flashed |
| Fasteners | Exposed or concealed, and the manufacturer-approved accessories |
| Deck and slope | Deck condition, minimum slope and required underlayment |
| Exposure | Hail, wildfire, snow, salt air and tree debris the product is approved for |
| Repairs | Who can supply the same profile, coating, trim or shingle line later |
FEMA’s sloped-roof fact sheet recommends metal panels tested to meet local code and wind-load requirements and installed to site-specific requirements. For shingles, it recommends ring-shank nails, code-rated shingles, roof cement along eaves, rakes, hips and ridges, upgraded underlayment on a full replacement, and flashing tied into the roofing. Neither material wins every storm on the label alone.
Energy claims need the exact product
The DOE Consumer Guide to Cool Roofs says cooling savings depend on solar reflectance, thermal emittance, climate, insulation and HVAC efficiency. Both asphalt and metal products are sold with reflective surfaces, so bare metal isn’t automatically a cool roof. DOE also says replacing a mechanically sound roof only to raise its reflectance is rarely economical.
Make the bids comparable
Each bid should list:
- measured roof area, slope factor, waste, and lengths of hips, ridges, valleys and trim;
- layers to tear off, disposal, deck inspection and a deck-repair unit price;
- the exact panel or shingle, underlayment, starter, closures, ridge and finish;
- flashing at every wall, chimney, skylight and vent;
- ventilation, gutters and rooftop equipment work;
- permits, inspections, cleanup, and product and workmanship warranties.
If one bid leaves out attachment, underlayment or flashing details, it isn’t really cheaper. If an installer gives you a life-cycle estimate, ask for its assumptions.
Repairs and upkeep
A leak may enter far from the stain you see, often at flashing, a penetration or an edge. A repair quote should name the entry path, any damaged deck or insulation, and compatible materials. Leave roof walking to a qualified roofer. From the ground, look for loose material, displaced trim, debris buildup and changes around penetrations. Neither roof is maintenance-free.
Keep the contract, the product and color schedule, permit records, photos of deck repair and flashing, and warranty registration. Before you sign, ask your insurer how the exact roof affects premiums, cosmetic-damage terms and deductibles.
Related guides
Sources
Frequently asked questions
Does metal roofing always last longer?
A material label is not a service-life guarantee. The panel or shingle product, coating, fasteners, flashing details, exposure and installation all affect performance.
Can metal go over existing shingles?
Sometimes, if code, the manufacturer’s instructions, the structure and the deck condition allow it. Covering the old roof can hide deck problems, so ask for a documented assessment.
Should I replace a sound roof for energy savings?
DOE says replacing a mechanically sound roof only to raise its reflectance is rarely economical. Weigh reflective products when replacement is already planned.