Standing in the street, you can see a missing tile and a sagging gutter. You cannot see any of the following, and any of the following can put water in your house.
A split pipe boot
The rubber collar on a plumbing vent, cracked along its top edge. Invisible from below, and the leak shows on a ceiling that may be a room away from the pipe.
Sealant that has let go
At the top edge of every flashing, around every skylight, at every metal seam, there is a bead of sealant with a lifespan. When it separates, it separates on the side you cannot see.
A cracked chimney crown
The concrete slab on top of a masonry chimney. It cracks with age, water runs down inside the brickwork, and the first sign is efflorescence on the chimney breast indoors, months later.
Underlayment taking direct sun
A single cracked or slipped tile exposes the membrane beneath it. The tile looks like a tile problem. It is a membrane problem, because underlayment in direct UV ages in months what it would otherwise age in years.
A blocked cricket
Behind a chimney or a wide vent, the small saddle that diverts water. Full of leaves, it is a dam, and the water it holds finds the flashing behind it.
Fasteners backed out
On a metal roof, thermal movement works screws loose a fraction of a turn at a time. From the ground the panel looks flat. From the roof, the screw heads are proud and the washers under them have perished.
The common thread
Every item on this list shares three properties. It is invisible from the ground. It is cheap when found early. And it announces itself, eventually, as a stain on a ceiling - by which point it has been leaking for a while and the repair has grown to include whatever the water reached.
That is the case for an annual look, made without any adjectives.
A Roof Sentry visit is a person on the roof, looking at exactly these six things, with a camera.
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