Roof leak diagnosis in DeWitt, NY: which roof is over that ceiling stain?

Housing of this age commonly has a back kitchen, a porch or a bedroom added on. Each one carries its own roof. So the useful first question is not whether the roof is bad. It is which roof is over the stain.

State code lets asphalt shingles go on a slope of 2:12 or steeper, and asks for double underlayment between 2:12 and 4:12. Below 2:12 the job needs a different product. If your stain sits under a low addition, ask the contractor to say what slope it has before anything is priced.

The other two causes are worth ruling out in houses like these. Warm room air leaks through ceiling gaps into the attic. Where an addition meets the old wall, the joint depends on flashing that was done right. The visit sorts these out in order.

You can narrow it down before anyone arrives. Use what you saw, not what you fear.

• Grew after a cold, dry night: go to the attic and look at the underside of the roof deck for frost or dark staining. Read about attic ventilation in DeWitt.
• Shows only in rain: look for the wall, chimney or vent pipe nearest the stain, then see flashing repair in DeWitt.
• Same spot after every patch: check what slope the roof above it has, then see low-slope roofing in DeWitt.

If none of these fits, or two fit at once, that is what the diagnostic visit is for. Our guide on telling a leak from attic moisture walks through the cold-night test in more detail.

A few facts make the visit faster and the proposal sharper. None needs a ladder.

• The room, and the wall the stain is closest to.
• The day it first appeared and whether it has grown.
• Whether it showed after rain, a thaw or a clear cold night.
• Any earlier patch on the same spot, and what it was.
• Where the bath fan duct ends.

At the visit, the contractor goes through the attic, the ceiling and the joints. What you take away is a written repair proposal for the job that contractor would carry out. It is a proposal for work. Whether to book it is your decision.