Phase one: inside the house
Water spots on ceilings and the tops of walls, bubbling paint, a musty smell in a closet under a valley. I measure from the stain to two walls so I can find the same spot from above. Most homeowners point me at a stain that is nowhere near where the water actually got in.
I also look at window heads and the tops of sliding doors on the upper floor, because a wall flashing leak often shows up there first.
Phase two: the attic
With a bright light I check the underside of the deck for staining, the rafters for dark tracks, and the insulation for damp or matted patches. Daylight around a pipe or at a ridge tells me a flashing has opened. I note ventilation while I am there, because attics in this heat that cannot breathe cook the roof from below.
If there is no attic access, or it is a vaulted ceiling, I say so in the report and rely more heavily on the surface check.
Phase three: the roof surface
I walk every slope that is safe to walk. On shingle I am looking for granule loss, curling, cracks and creased tabs; on tile, for slipped, cracked and broken pieces, and for the condition of the felt where I can lift a tile to see it. On flat roofs, for ponding rings, open seams and blisters.
Ridges, hips and the north and east leading edges get extra attention after wind season.
Phase four: flashings and penetrations
This is where most leaks live. Chimneys, skylight curbs, plumbing vents, furnace flues, satellite dish mounts, roof-to-wall junctions and the metal in the valleys. I check whether flashing is properly lapped and cut in or just sealed over, and whether the sealant has split in the sun.
On tile roofs I check the bird stops and the eave closures too, since open eaves let wind-driven rain and rodents in.
What you get
A written report with photos of every issue, a verdict, and if work is needed, a scope with a repair option and, only if justified, a replacement option. For a house purchase I also give a rough remaining-life opinion so you can budget.
I do not do drive-by inspections. If I cannot get on the roof and into the attic, I tell you what I could not see.