How long does a roof last

An architectural asphalt roof lasts 25 to 30 years, three-tab 15 to 20, metal 40 to 70, tile 50 or more, and slate 75 to 150. Those are the ratings. What most roofs actually achieve is shorter, and the gap is almost always ventilation.

Knowing where a roof sits in its life is the difference between budgeting for a $14,000 replacement and being surprised by one.

Expected life by material

The warranty is not the life

A "lifetime" shingle warranty covers manufacturing defects, prorated after the first decade or so, and it is voided by inadequate ventilation, improper nailing, and installation over an existing layer.

Almost no roof is replaced because the shingles were defective. They are replaced because they wore out, and wearing out is not a defect.

Read what the warranty covers and read what voids it. The second list is shorter and more useful.

What actually determines it

Ventilation. The single largest factor. An attic that reaches 150°F in summer cooks the shingles from underneath and can take a third off the roof's life. This is why the ventilation article is worth reading before the replacement one.

Sun. A south or west slope in Arizona ages faster than a north slope in Michigan. Roofs frequently fail on one elevation while the others are fine.

Color, slightly. Dark shingles run hotter. With good ventilation it matters little; without it, it compounds.

Installation. Correct nail count and placement, proper underlayment, ice and water shield where required, flashing done rather than sealed. A good roof badly installed fails early and the warranty will not help.

Trees. Shade holds moisture and grows moss. Branches abrade shingles in wind. Falling limbs do the obvious.

Layers. A roof installed over an existing one runs hotter and lasts less.

Reading your own roof

From the ground with binoculars, and from inside the attic:

Granules in the gutters. Asphalt shingles shed some for the first months after installation. Steady accumulation years later means the surface is wearing through, and that is the beginning of the end.

Curling at the corners or cupping in the middle. The shingle is drying out and losing its flexibility.

Bald patches where the granules have gone and the asphalt shows.

Shingles that look darker in one area — often trapped moisture.

Daylight through the roof deck from inside the attic.

A sagging ridge line sighted along from the ground, which is structural rather than cosmetic.

Three or more of those on a roof past twenty means start getting quotes rather than waiting for a leak.

Knowing the age when you did not install it

• Ask the previous owner or check the sale disclosures
• Permit records at the local building department, which are usually public
• A roofer can date shingles from the product and the wear
• Look in the attic: roofers often write the date on a rafter, and old shingle wrappers sometimes remain
• A home inspection report from the purchase will estimate it

Planning for it

A roof is the largest predictable expense a house has. It is predictable in a way a furnace failing is not, because it is a slow wear-out with visible warning.

At the twenty-year mark, get an inspection and start setting money aside. Replacing a roof on your own schedule, in the shoulder season, with three quotes, costs noticeably less than replacing it in August after a leak, from whoever can start this week.

Frequently asked questions

Can I extend my roof's life?

Yes, and cheaply: fix the ventilation, keep the gutters clear, cut back overhanging branches, and repair flashing failures promptly. None of it makes a worn shingle new, but it stops the avoidable causes.

Does a new roof help a house sell?

It removes an objection rather than adding a premium. Buyers discount for a roof near its end far more than they pay extra for a new one, so the value is in the avoided discount.

Should I replace early to get it over with?

Not usually. A roof with five good years left has five years of value in it. The exception is if you are having other work done that would be disturbed later, or selling into a market where an old roof kills the sale.

What is the most common reason a roof fails early?

Ventilation, followed by installation. Both are decided when the roof goes on, and neither is visible afterwards without looking in the attic.

Do metal roofs really last 50 years?

The panels do. The fasteners and sealants at penetrations do not, and those need attention every 15 to 20 years. A metal roof is a long-life roof with a maintenance schedule, not a fit-and-forget one.