Which parts of your roof are due, and which can wait

A roof is not one thing with one age. The shingle, the flashing, the gutters and the attic each wear out on their own schedule, and on a house that has been re-covered once already, some of those schedules started long before the visible surface did. Give it the year the house went up and what has been replaced since, and it will lay out where each part stands.

Treat this as a way to decide where to look, not a verdict. It sets ages against the service lives the trade generally expects. A roof on a shaded north slope can outlast the range by a decade; one over a hot knee-wall attic can fall short of it by the same. Installation and exposure count for more than the calendar.

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Set the house, then set what has been done

When was the house built? What is on the roof now?

What has already been replaced?

Leave a row on Original when it has never been replaced, or when the work happened under a previous owner and no paperwork came with the house. Not knowing is a legitimate answer here.

Roof covering Flashing at walls, valleys and penetrations Underlayment and ice-and-water shield Gutters and downspouts Attic ventilation Skylights (if you have them) Chimney crown, cap and masonry (if you have them) Fascia and soffit Siding or exterior cladding Window seals

The trouble is usually one layer down. On these houses the roof you can see is often not the only one. Which is why flashing, not shingle, is the item most worth knowing the age of.

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1 Ridge caps. Thin, exposed, and the first course to lift.
2 The field. The course you can see, over the underlayment you cannot.
3 Valleys. Leaf load mats where two slopes drain as one.
4 Flashing. Old masonry, and the wall an attached house shares.
5 Vent boots. The rubber cracks years before the shingles around it are done.
6 Eaves and ice dams. Where the melt runs out of warm roof and turns back into ice.

Why a new shingle can be sitting on an old roof

When a roof is laid over the previous one, which was the common practice here for a generation, the surface looks new and the underlayment beneath it is whatever was there before. The first line of defense resets. The second does not. That is why this page asks about the underlayment on its own, and why on many houses the honest answer is that no one knows when the last full tear-off happened.

Flashing works the same way. Sealing the existing metal at the chimney and the walls is faster than replacing it, and it is done often enough that a roof from five years ago can be carrying flashing from thirty years ago. If someone tells you the roof is recent, the question worth asking next is whether the flashing is.

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This tool may be copied or linked to freely, with credit to watchungroofing.com. If it helps a condo association or a first-time buyer in one of these towns work out what they are looking at, it has done its job.

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