How to Repair an Asphalt Shingle Roof

The stain on the ceiling is almost never directly under the hole. Water follows the slope of the deck, then travels along a rafter or a run of sheathing until something stops it. Start in the attic on a dry day with a flashlight and look for dark streaking, rusted nail shanks, or daylight at the deck seams. Follow the streaking uphill; the entry point is at the top of it.

Outside, the usual suspects are in this order: pipe boots, step flashing where a roof plane meets a wall, valleys, chimney counterflashing, and only then the field of the shingles themselves. A cracked rubber pipe boot is the single most common leak we find on East Tennessee roofs in the fifteen-to-twenty-year range, and it costs almost nothing to fix.

Work on a mild, dry day. Asphalt shingles are brittle when cold and they tear when hot, so early morning in spring or fall is ideal. In July the afternoon sun will make a Knox County roof hot enough to scuff granules off every shingle you walk on.

Break the sealant strip under the shingle above the damaged one with a flat pry bar, then work the bar under and pop the nails holding the damaged shingle — there are usually four in the shingle itself plus two driven through it from the course above. Slide the old piece out, slide the new one in, nail it in the same line, and hand-seal the tabs with a dab of roofing cement under each one.

Nail placement matters more than most people expect. High nailing, above the nail line, means the shingle is only held by the course above it and the next strong wind takes it. Keep the nail flush, not driven through the mat.

A nail pop shows as a small raised bump in the middle of a shingle. Pull the nail, seal the hole, and re-nail an inch or two away. Smearing sealant over the head without pulling it just hides the hole while the nail keeps working its way up.

Flashing repairs are where patch jobs go wrong. Step flashing at a wall has to be woven one piece per shingle course and tucked behind the siding or under the counterflashing. A continuous bead of caulk across the joint will hold for a season or two and then fail, usually invisibly, while water runs behind the wall sheathing.

Anything done with a tube of sealant should be treated as a temporary measure with a date on it. Sealant is the right answer for a small puncture you found in a rainstorm. It is the wrong answer for a valley or a chimney.

Curling or cupped edges across a whole slope, bare patches where the granules are gone, and shingles that crumble when you lift them all mean the mat has aged out. Patching one section of a roof in that condition buys a few months and makes the next storm's damage someone else's surprise.

Soft decking is the other stopping point. If the roof gives underfoot, the sheathing is wet, and no shingle work fixes that. At that point you are pricing a tear-off with deck replacement, not a repair, and it is worth getting the number before deciding what to do with the house.

Roof condition is one of the few things that can stop a conventional sale outright. An appraiser on an FHA or VA loan will flag an aged roof, and a lender may require it replaced before closing — which puts the cost on the seller, before the money arrives.

That is a real decision point, not an automatic reason to replace. Sometimes replacing the roof and listing is clearly the better number. Sometimes selling as-is is, particularly if the house needs other work as well. We do both sides of that work, so we can price the roof honestly whether we end up doing the repair for you or buying the house.