Idaho · Metal vs asphalt

Metal roof vs asphalt shingles in Idaho

Asphalt costs less today and lasts about 20 years on published averages; an Interlock® aluminum roof costs more today and is built to be the last roof you buy. For a house you'll keep in Idaho, compare both written prices over the years you'll own it, counting the next asphalt replacement.

Reviewed by Scott Plumptree, Director of Marketing, The Interlock Group · Updated October 8, 2026

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Asphalt

About 20 years

NAHB / Bank of America study, 2007.

Aluminum

Known to last over 100 years

A property of the metal, not a promise.

Hail

UL 2218 Class 4

Interlock Slate, Cedar Shingle, Shake and Mediterranean Tile (Intertek, for Delta Building Products).

Side by side

Interlock aluminum roof compared with asphalt shingles
	Asphalt shingles	Interlock® aluminum roof
Life expectancy	About 20 years (NAHB / Bank of America, 2007)	Aluminum has been known to last over 100 years; a property of the metal, not a promise
Material warranty	Varies by brand and line; read who the warrantor is	Guardian Lifetime Limited Material Warranty: material and finish, original purchaser, transferable once
Hail	Impact-rated lines exist; granules can be knocked loose	Slate, Cedar Shingle, Shake and Mediterranean Tile carry UL 2218 Class 4 (Intertek); large hail can still dent
Wildfire embers	Fiberglass asphalt commonly reaches Class A as an assembly; debris on it can still ignite	Aluminum does not ignite; Class A Fire Rated Available, as a complete assembly
Sun and heat	Hot, dry summers age the asphalt and loosen granules	Alunar® finish with a 30 Year Alunar® Coating Warranty
Freeze–thaw	Water under curled tabs freezes and lifts them	Absorbs no water; interlocked courses have no tabs
Wind	Tabs can lift and blow off in storm fronts	Panels lock on four sides; wind warranted to 120 mph when installed to manufacturer specification
Snow	Holds snow	Sheds snow; snow guards planned where slides would land
Weight	Heavier per square foot than aluminum	About 0.41 to 0.59 lb per sq ft installed, by profile (ICC-ES ESR-1790)
At the end	Torn off and sent to landfill, then replaced	Aluminum is recyclable
Up-front price	Lower	Higher

Asphalt life expectancy: National Association of Home Builders and Bank of America Home Equity, Study of Life Expectancy of Home Components, February 2007 (a US study; local weather, design, material quality and maintenance all move it).

Is a metal roof worth it in Idaho?

The honest answer depends on how long you'll own the house. An asphalt roof costs less today and will be torn off and replaced, likely more than once, while you live there. An Interlock® aluminum roof costs more today and is built to be the last roof you buy.

In southwest Idaho, three things tip the comparison: hail from spring and summer thunderstorms (on June 26, 2026 a storm left several inches of small hail on the ground in northwest Meridian), wildfire embers wherever homes meet the foothills or rangeland, and long, hot summers that age asphalt. The way to decide is with real numbers for your house: a written asphalt price and a written Interlock® price, compared over the years you expect to stay.

When asphalt is the better choice

You plan to sell within a few years and the buyer won't pay for the roof.
The roof's slope is below 3/12 (every Interlock profile needs at least 3/12).
The budget today simply doesn't allow it, and the current roof can't wait.

If you're replacing asphalt now

Most Treasure Valley homes have asphalt roofs. A single layer of asphalt can be roofed over only if our inspection finds it suitable and your city allows it (Nampa's reroof permit allows no more than two layers at completion); otherwise it comes off, along with any soft decking the inspection finds. Ice dams are a separate question from the roof covering: they come from heat loss and ventilation, and ice damming is a stated exclusion of the material warranty, so we look at your attic with you.

Questions, answered

Is a metal roof better than asphalt shingles?

For a house you plan to keep, usually yes: a metal roof absorbs no water, has no shingle tabs for wind or freeze–thaw to lift, sheds snow, does not ignite, and outlasts asphalt, which a 2007 NAHB / Bank of America study put at about 20 years. Asphalt costs less up front.

How long do asphalt shingles last in Idaho?

Published averages put asphalt shingles at about 20 years (NAHB / Bank of America, 2007), and local weather, design, material quality and maintenance all move that. In southwest Idaho, hot summer sun, hail and freeze–thaw cycles work on asphalt every year.

Is a metal roof better in hail?

Compare the impact rating of the exact products. Interlock's Slate, Cedar Shingle, Shake and Mediterranean Tile profiles carry a UL 2218 Class 4 impact rating, verified by Intertek for Delta Building Products. Large hail can still leave cosmetic dents on aluminum.

Is a metal roof louder than shingles?

Installed over a solid deck and underlayment, as residential Interlock® roofs are, it isn't the drumming of bare metal on an open-framed barn.

Does a metal roof increase home value?

We don't publish a number for that; it depends on your market. What a buyer gets is a roof that won't need replacing and a Guardian Lifetime Limited Material Warranty that transfers once.

Can a metal roof go over asphalt shingles?

Sometimes: a single layer of asphalt can be roofed over only if an inspection finds it suitable and your city allows it. Otherwise it comes off first.

How do I compare the cost of metal and asphalt?

Get both prices in writing and compare them over the years you'll own the home, including the next asphalt replacement. For an Interlock® roof, book a free consultation or call (208) 842-4762.

Sources

Product specifications are the manufacturer's (Interlock Roofing). Reviewed by Scott Plumptree, October 8, 2026.

Related guides

Get a written price to compare.

A written price after your roof consultation, at your home or on Zoom. Interlock Metal Roofing (PNW) Inc. · 3295 W Elder St, Suite 209, Boise, ID 83705

Get a free quote (208) 842-4762