Roof leaking or ice at the eaves? Call and reach a local roofer.

What should you do first when a ceiling starts dripping in a Newton house?

Catch the water, move belongings out of its path and photograph the stain and the ceiling before anything else. Keep clear of any fixture or outlet that water is touching. Then call, and say where inside the house it shows up and whether the weather outside is snow, rain or thaw.

Where water appears inside is rarely where it enters the roof. It can run along a rafter or down the face of a chimney before it drips, so the stain tells the roofer where to start looking, not where the hole is. Notes on timing help too: a leak that appears only during a thaw points at meltwater and the eaves, while one that shows up in a summer downpour points at flashing or a valley.

Stay on the ground. Roofs in New England are steep, wet or iced over for much of the winter, and the photos you take from the yard or from an upstairs window are more useful to a roofer than a trip up a ladder..

• Catch it: a bucket or a tub under the drip, with a towel in the bottom to stop splashing.
• Clear it: furniture, rugs and anything electrical out of the wet zone.
• Record it: dated photos of the ceiling, the wall and any attic staining you can see from the hatch.
• Note it: when it started, what the weather was doing, and whether it stopped when the weather changed.
• Call: describe what you saw and ask the roofer what they need next.

Why do Newton roofs wear differently from roofs in newer suburbs?

Newton's median house dates from 1942 and about 49 percent were built before 1940, so many roofs sit on old decking with chimneys, dormers and valleys that newer houses lack. More joints mean more places for water to find a way in, and repairs often have to match slate or copper.

Mid-century houses in the surrounding towns tell a different story. Needham's median home dates from 1965 and Dedham's from 1956, and many of those houses carry asphalt shingles on simpler roof shapes. Framingham has 1950s ranches with low-pitched roofs, and Lincoln has about 70 modernist houses. The roof you have decides which problems to expect, which is why the first question on the line is about the house, not the leak.

Closer to the Charles, closely built multi-family houses and triple-deckers add shared roofs and flat sections to the mix. Those roofs hold standing water in a way a steep one does not, and the failures show up at seams and drains rather than at shingles.

What does a Massachusetts roofer have to be registered for?

Massachusetts issues no roofing license. Contractors doing work on homes register as Home Improvement Contractors with the Office of Consumer Affairs and Business Regulation, and the building permit for roof work is normally pulled by a holder of a Construction Supervisor License issued by the Board of Building Regulations and Standards.

So the useful questions to ask any roofer are practical ones. Ask for the Home Improvement Contractor registration number that belongs on a written home improvement contract, and ask who will pull the permit if the job needs one. One published guide reports that larger home improvement contracts need to be in writing with a registration number on them, and that deposits are limited; check mass.gov for the current rule rather than relying on a summary.

The registration and license guide walks through what each credential covers and what to ask to see, and the contract guide covers deposits and cancellation.

How do you decide between a repair and a new roof on an older house?

Look at how widespread the trouble is. A few lifted shingles, one failed flashing or a single leaking valley usually points to a repair. Curling or brittle shingles across a whole slope, soft decking or repeated leaks in different places point toward replacement, which the roofer should explain after looking in the attic.

Published guides give asphalt shingles roughly 20 to 30 years, cedar 30 to 40 and slate 75 to 100 or more. Those are third-party figures, and a roof's real age depends on its ventilation, its exposure and how it was installed. The roofer's inspection matters more than the calendar.

If you are comparing options, read the pages on roof repair and roof replacement, and ask any roofer to put the repair option and the replacement option side by side in writing so you can see both.