Interior Painting right here in Medford, Massachusetts.

Census figures put the median construction year for Medford housing at 1942, and 48.8% of the city's 25,587 units date from 1939 or earlier. A house of that age may still have its original plaster walls and wood trim, and either one may carry many coats of paint by now.

That history shapes an interior job more than the color does. A room can look fine from the doorway and still hide hairline cracks, loose ceiling plaster or a window stool built up with layers of old paint. Those are better found and priced during the estimate visit than discovered once the walls are open.

Plaster walls and ceilings

Old plaster moves. Seasonal changes in humidity open and close cracks along door headers and at ceiling corners, and a ceiling that sags slightly or sounds hollow when tapped may be pulling away from its lath. Painting over that only hides it for a season.

The repair depends on what is wrong. Fine cracks get opened, taped with mesh and skimmed; loose sections can often be reattached with plaster washers before patching; badly failed areas may need a new skim coat. Ceilings get primed after repairs so the patches don't show through as dull spots under a flat finish.

• Check ceilings for sagging or bulges before choosing a finish
• Look at stair walls and hallways for wear and earlier patching
• Ask how cracks will be treated, not just whether they will be filled

Lead on trim, doors and windows

About 75.9% of local housing was built before 1980, and the federal lead-paint cutoff is 1978. The City's Housing Production Plan names lead paint among the hazardous materials an older housing stock can indicate. Indoors, the risk concentrates where painted surfaces rub or get sanded: window sashes and sills, door edges, stair treads and baseboards.

Under the EPA's Renovation, Repair and Painting rule, a contractor paid to disturb paint in a pre-1978 home must be certified and follow lead-safe practices. Indoors, that means plastic sheeting over floors and doorways, misting before scraping, no dry power sanding without HEPA extraction, and a careful cleanup and check at the end. Our lead-safe painting page explains the full process and the state rules that apply when children live in the home.

Mid-century and newer rooms

Not every house here is that old. The 1950s added 2,417 units, more than any other decade since 1940, and about 12.9% of units went up in 2000 or later. Rooms from the later decades are more likely to be drywall, where the job is about dents, nail pops, taped seams that have cracked at corners and choosing a sheen that hides the wall's flaws.

A house can mix both: a 1920s front parlor with plaster, and a 1990s addition or finished basement with drywall. Each surface gets its own patching material and primer, so the painted result looks continuous even if the walls underneath are not.

Two-family homes and shared stairways

Two-unit buildings hold 27.1% of the city's housing, close to the 33.8% in detached single-family homes. If you own a two-family, interior work may cover your own unit, a tenant's unit between leases, and a front hall and staircase both households use.

Shared halls take planning: one side of the stair painted at a time, wet-paint signs, and a schedule both households know in advance. Pre-1978 common stairways also need the same lead-safe containment as any other room, since everyone walks through the dust zone. For condo-owned two-families, see the condo painting page.

Scheduling inside work

Interior painting does not depend on outdoor temperatures, which makes late fall and winter good months for it, as long as rooms can be ventilated and heated. Our post on winter interior painting covers drying times and ventilation. Homeowners in West Medford, Medford Hillside, Fulton Heights and Lawrence Estates can book a walkthrough the same way.