# How long does a roof last?

You are standing in the yard looking up at your roof, trying to work out how many years it has left. It is a hard thing to guess from down there, and the two ways to get it wrong are both expensive. If you spend the money too early, you paid for a roof that still had years in it. If you wait too long, you find out from a stain spreading across a ceiling.

The answer depends on what your roof is made of. Most houses in this country are covered in asphalt shingles. [The Asphalt Roofing Manufacturers Association says four out of five homes are roofed with them](https://www.asphaltroofing.org/frequently-asked-questions/). So for most readers, this is a question about asphalt, and asphalt has a fairly well known range.

## How long an asphalt shingle roof lasts

Plan on roughly 20 to 30 years, depending on which kind of shingle is up there. [InterNACHI's life expectancy chart for homes puts basic three-tab asphalt shingles at about 20 years and architectural shingles at about 30](https://www.nachi.org/life-expectancy.htm). Architectural shingles are the thicker, layered ones that look like they have depth to them.

That is a starting number, not a promise. The same chart says the real life of a roof depends on local weather, the design of the building, the quality of the materials, and how well it has been kept up. A few things move the number the most:

- **Heat and sun.** InterNACHI says hot climates drastically reduce asphalt shingle life. A roof in Phoenix and the same roof in Portland are not on the same clock.
- **Storms.** The chart also says roofs in places that get hail, tornadoes, or hurricanes can wear out sooner, or can take damage in one spot that needs repair to protect everything around it.
- **Attic ventilation.** [ARMA says ventilation moves heat out of the attic, and that this helps prolong the service life of the roof](https://www.asphaltroofing.org/frequently-asked-questions/). It also moves out the water vapor your household makes every day, which is what causes mold and wood rot up there.
- **What the weather has already thrown at it.** [GAF, one of the big shingle makers, says there is no expiration date on a shingle](https://www.gaf.com/en-us/blog/your-home/when-is-it-time-for-a-new-roof-281474979970414), and that weather, location, moisture, and sun all change the condition of a particular roof.

If your house has something other than asphalt, the clock runs much longer. That same InterNACHI chart lists metal at 40 to 80 years, slate at 60 to 150, and clay or concrete tile at 100 or more.

There is one age worth writing on your calendar. [ARMA says that if a home's roof is more than 20 years old, it is a prime candidate for reroofing](https://www.asphaltroofing.org/frequently-asked-questions/). That does not mean a 21-year-old roof is finished. It means 20 years is the point where the question stops being a guess from the yard and starts being worth a professional opinion.

**Do you know how old your roof is?**

Tobi keeps the roof's age, the date of the last inspection, and who came to look at it in one place your whole household can open.

[Download on the App Store](https://apps.apple.com/us/app/tobi-home-maintenance/id6784417439)

## How to tell if your roof needs replacing

You can learn most of what you need from the ground and from your attic. Do not climb up there to check. [ARMA puts it in capital letters: do not climb on the roof, because walking on it is dangerous and can damage the roof](https://www.asphaltroofing.org/frequently-asked-questions/). GAF says the same thing and tells homeowners to leave the climbing to the pros. Binoculars and a flashlight are the only tools this job needs.

Here is what to look for.

- **Cracked, curled, or missing shingles.** ARMA says to walk around the house with binoculars and look for exactly those three things. GAF lists missing, torn, or curling shingles, along with holes and cracks in them, as signs that a roof needs attention. A few bad shingles in one spot is a different problem than bad shingles all over.
- **Bare patches where the granules are gone.** Those little bits of crushed rock on the surface of a shingle protect the asphalt underneath. GAF says occasional granule loss is normal, but excessive loss, especially the kind that leaves bare patches, can be a symptom of aging. ARMA also tells you to watch for excessive loss of those protective mineral granules.
- **Stains or wet spots in the attic.** ARMA says to take a flashlight into the attic and look at the underside of the roof deck and the rafters for stains or wet spots, because those mean water is getting in. [GAF adds the signs you see from inside the rooms](https://www.gaf.com/en-us/plan-design/homeowner-education/roof-damage): watermarks on walls or ceilings, peeling paint, and mold or mildew.
- **Sagging.** GAF lists sagging on the roof as a sign of damage, and says sagging sheathing, the plywood layer the shingles are nailed to, points at decay underneath. Sagging is not something to watch for a season. Call a roofer about it.
- **Leaks that keep coming back somewhere new.** One leak in one spot is usually a repair. Water showing up in a different place every heavy rain is the roof as a whole telling you something.

If you do not know how old your roof is, GAF suggests checking the inspection report from when you bought the house. You can also ask a roofing company or a building inspector to look at it and estimate its age and condition.

## Repair it or replace it?

[GAF draws the line in a way that is easy to use](https://www.gaf.com/en-us/plan-design/homeowner-education/roof-damage): if the roof is not very old and there are a few loose or damaged shingles, you may be able to replace just those, but broader or more extensive damage may mean it is time for a new roof.

So a young roof that lost shingles in one storm is usually a repair. A roof past 20 years with wear showing all over it, brittle shingles, leaks in new places, or a soft deck is a replacement conversation. Your roofer should be able to tell you which one you have, and should be able to say why.

Two things are worth knowing before you say yes to anything. ARMA says new asphalt shingles often can go straight over an existing roof, but not over a deck that is warped, rotted, or otherwise unsound, and not over hard or brittle material. It also says some local rules do not allow a third layer, so a house that has already been shingled twice may need a tear-off. And GAF says to always get a few estimates and go through the details with the contractor. [How to tell if a contractor quote is fair](/blog/how-to-tell-if-a-contractor-quote-is-fair) is what I do once I have more than one number in front of me.

## Write down the roof's age and every visit

A roof is the one part of the house where the date matters more than anything you can see. "The roof is about 20 years old" and "the roof is about 10 years old" lead to two different decisions about the same curled shingle. Most people genuinely do not know which one they have, because the roof went on before they moved in, or it went on so long ago that the year has blurred.

So write down four things and keep them somewhere the household can find them:

- When the roof went on, or your best estimate and where it came from
- The date of the last inspection and who did it
- What they found, in their words
- What they said to watch for next time

[Tobi's maintenance log](/features/maintenance-log) is where I would keep it. The roof goes in as its own record in the home, with its age and notes attached to it. A yearly look from the ground becomes a recurring task on that record, so it comes up as due instead of waiting on someone to think of it. Marking it done leaves a line in the history with the date, who did it, and what they saw that year. Nothing gets written over, so five years of checks reads as five checks.

The roofer goes in as a contractor, with their trade and phone number, and the work stays attached to their name. [How to keep track of home contractors](/blog/how-to-keep-track-of-home-contractors) is the longer list of what is worth saving about the people who work on your house.

Everyone in the [household](/features/household-sharing) sees the same record in real time, on their own iPhone or iPad, or on an Apple Silicon Mac. The person who talked to the roofer is not always the person who will be home the next time one comes. Tobi does not inspect your roof and it does not hire anyone. It is the written record of what happened to your own house.

One more job belongs next to this one. Clogged gutters hold water at the edge of the roof, which is the last place you want it sitting. [How often to clean your gutters](/blog/how-often-to-clean-your-gutters) is the schedule for that.

**Home maintenance, finally shared.**

Tobi keeps the inspections, the repairs, and the history of who did them in one place your whole household can open.

[Download on the App Store](https://apps.apple.com/us/app/tobi-home-maintenance/id6784417439)

## What I would do about a roof I was unsure of

I would start by finding the age, even a rough one, because that single number changes how I read everything else.

Then I would walk the yard with binoculars and look for curling, cracks, missing shingles, bare patches, and any dip in the line of the roof.

Then I would take a flashlight into the attic on a bright day and look at the underside of the deck for stains and wet spots.

If the roof is past 20 years, or if any of that turns something up, I would call a licensed roofing contractor and have them go up instead of me. Then I would write down what they found, so the next time I am standing in the yard looking up, I am not starting over.