Start with the share of the roof that is bad
Repairing roofs is the subject of a technical brief from the Department of Energy, which quotes a guideline from a builders' journal: when more than a tenth of a roof calls for repair, a new roof is the recommendation. Treat it as a place to start rather than a ruling. Tally what shows from the ground, then ask a roofer to tally the rest. Ten curled shingles on a roof with two slopes can fall under the line, while patches on every slope may not.
Sign by sign: patch, watch or replace
| What you see | Lean toward | What to ask the roofer |
|---|---|---|
| One or two cracked or missing shingles, the rest flat | Patch | Are the shingles around the damaged ones sound? |
| A stain that shows only after wind-driven rain | Patch, after a flashing check | Where does the roof meet a wall or chimney? |
| Patches on several spots of the same slope | Watch, then compare | Does the repaired area near 10 percent of the roof? |
| Gray grit at the downspouts, bare spots and curled edges across a slope | Ask about replacement | How much of the surface is worn? |
| Daylight through the boards, or wet and flattened insulation | Repair or replace, deck first | Is the deck still sound under the stain? |
| Water that stays on a flat roof for two days | Repair drains and seams, ask about slope | Is there enough slope for the membrane? |
What a patch can and cannot reach
A repair deals with whatever failed, whether that is two shingles, a length of flashing or a nail that backed out. The same brief adds a condition: wet insulation has to be removed. That makes the attic part of the repair question, and the ceiling stain may be the smaller part of what got wet.
What a new roof redoes that a patch cannot
A replacement renews every layer in one pass: the covering, the underlayment, the flashing and, when needed, boards of the deck. FEMA's high-wind guidance for shingle roofs lists what to listen for. Underlayment on the deck, roofing nails instead of staples, six nails per shingle at the eaves, sealed tabs and careful flashing at wall joints all come with a tear-off. A patch borrows what is already there.
When the roof is not asphalt shingles
The National Park Service's overview names the main coverings: built-up roofing, single-ply sheets such as EPDM, PVC and TPO, modified bitumen, metal and sprayed foam. Metal panels come in standing-seam and exposed-fastener types, and the Building America Solution Center notes that condensation can form under metal. On a flat roof, the asphalt roofing trade group treats water that stays 48 hours as ponding. The patch-or-replace question changes with each material.
Reading the attic before deciding
The attic shows what the shingles hide. Look for stains on the rafters, dark streaks under the boards, daylight, and insulation that is damp or flattened. The asphalt roofing trade group's inspection advice after Sandy takes in the attic side of the roof along with the view from the ground. FEMA adds that a sagging ceiling may be holding water, and a Pennsylvania flood-recovery sheet says drywall that stays wet long enough falls apart when bumped.
Two- and three-family houses: living under the work
Tenants live with the result of a roof job. Tell the landlord or property manager first; repairs are arranged and approved at that end. A patch leaves most households undisturbed, while a tear-off is loud and drops debris. New Jersey's insurance department says the policyholder picks the contractor, not the insurer, and asks for photographs before cleanup. Tenants help by sending dated pictures to the landlord or manager.
Still stuck between the two?
Photos of the roof, the attic and the ceiling shorten the conversation. Read about roof repair and roof replacement for the details of each. Next step: call (862) 418-5296 and describe the age of the roof, what you can see and where the water shows.