Remodeling an older home in Wilmington: what’s behind the walls

Many houses in Wilmington and the Brandywine Valley were built generations ago: brick rowhouses and twins in the city, stone farmhouses and mill-era homes along the creek, early twentieth-century houses in the older suburbs. They are often better built than people expect. They also rely on materials and methods no longer used, and some of what is behind their walls needs attention in a remodel. None of it is a reason to avoid a project, only a reason to know what you are likely to find and plan for it.

Plaster and lath

Most homes built before the 1940s have plaster walls rather than drywall. In the oldest houses, the plaster was applied in coats over thin strips of wood lath; from the early twentieth century, many builders used gypsum or metal lath instead. Plaster is dense, quiet and durable, and where it has pulled away from the lath it can often be reattached rather than torn out.

When walls must open, patches need to match the plaster’s thickness, which is usually greater than standard drywall. Removing plaster also makes heavy dust that, in a pre-1978 house, may carry lead from old paint.

Balloon framing and old-growth lumber

Many houses built before the 1930s or 1940s use balloon framing, in which wall studs run continuously from the foundation sill to the roof rather than stopping at each floor. That leaves open cavities connecting the basement to the attic. They are handy for running new wires, but they also let fire and air travel from floor to floor, so when walls are open it is good practice, and often a code requirement, to add fire blocking at each floor line.

The lumber is often old-growth wood, denser than most framing lumber sold today and frequently cut to full dimensions: an old two-by-four may truly measure two inches by four, so new lumber won’t sit flush with it without shimming. Over the decades, joists may also have been notched for pipes, and some will need reinforcement to carry a stone countertop or tile floor.

Knob-and-tube and other older wiring

Knob-and-tube wiring, used in American homes from roughly the 1880s into the 1940s, runs individual conductors through porcelain knobs and tubes in walls and ceilings. It has no ground wire, its insulation becomes brittle with age, and it was designed to shed heat into open air, so it should not be buried in insulation. Many houses have had it partly replaced, leaving wiring from several eras spliced together in hidden places.

Knob-and-tube that is still live is usually replaced in any area being remodeled, and often throughout the house. Old panels and ungrounded circuits may also need updating to support a modern kitchen or heat pump. An electrician’s survey during design shows how much of the house is affected.

Galvanized and cast-iron plumbing

Galvanized steel supply pipe was common in houses plumbed before the 1960s. It corrodes from the inside, so weak water pressure and discolored water are typical signs. It is usually replaced with copper or PEX wherever walls are open, and often throughout the house.

Cast-iron drain lines are a different story. Cast iron can last a very long time and is quieter than plastic, but old pipe can crack or rust through along the bottom, where water runs. A camera inspection of the main drain and sewer line costs far less than finding a failure after the new floor is down. In some older houses, the water service line from the street may also be lead. Your water utility may have records, and replacement is worth discussing during design.

Lead paint and the EPA RRP rule

Any house built before 1978 may contain lead-based paint, often beneath newer coats. Intact paint is a much smaller concern than the dust created by sanding, scraping or demolition, which is especially hazardous for young children and pregnant women.

The U.S. Environmental Protection Agency’s Renovation, Repair and Painting (RRP) rule covers paid work that disturbs painted surfaces in homes built before 1978. Under the rule, firms doing that work must be EPA-certified, a certified renovator must be assigned to the job, and lead-safe work practices are required: containing the work area, avoiding prohibited methods such as open-flame burning and power sanding without HEPA dust collection, and cleaning and verifying the area before it is reoccupied. The contractor must also give the owner the EPA’s Renovate Right pamphlet before work begins. Small repairs that disturb only a few square feet of paint are exempt, though window replacement and demolition are covered regardless of size, and the rule does not apply where testing by a certified professional shows the paint is not lead-based. Whoever you hire, ask to see the firm’s certification.

Asbestos in flooring, insulation and elsewhere

Asbestos appeared in many building products through much of the twentieth century. In older houses, common places to find it include vinyl or asphalt floor tiles, especially nine-inch squares, and the black adhesive beneath them; insulation on old heating pipes and boilers; vermiculite attic insulation; some textured ceilings and joint compounds; and cement-based siding or roof shingles. Intact and undisturbed, they pose little risk; the concern is cutting, sanding or breaking them.

Test before demolition, not during it. Samples of suspect materials go to an accredited laboratory, and if asbestos is found, it is removed or encapsulated by a qualified abatement contractor under state and local requirements before other work in that area proceeds. Having results during design means abatement can be scheduled and priced instead of stopping the job.

Stone foundations and moisture

Many older homes in the Brandywine Valley sit on fieldstone or rubble foundations laid in lime mortar. They are rarely watertight, and damp basements are common. Most moisture problems begin outside: gutters that overflow, downspouts that empty against the wall and soil that slopes toward the house. Fix those first, then add interior drainage or dehumidification where needed.

Repointing calls for mortar compatible with the original. Hard, cement-rich modern mortar can trap moisture and damage softer stone and old brick over time. If you plan to finish a basement in an older house, the foundation and drainage come first.

Settling floors

A floor that slopes toward the middle of the house is common in older homes and isn’t automatically a structural emergency. Typical causes are undersized or notched joists, a center beam or basement posts that have settled, and walls removed in earlier renovations without new support. A structural review during design identifies which applies. Fixes can include sistering joists, adding a beam or new posts on proper footings, or leveling the floor surface over existing framing.

It helps to decide how flat is flat enough. Fully leveling an old floor can disturb ceilings, door openings and trim, so the goal is often to stop further movement and level the floor where it matters most, such as under cabinetry and tile.

Exploratory openings reduce surprises

The way to manage older-home conditions is to look before you commit. During design, we make small, deliberate openings in walls, ceilings and floors wherever the plan depends on what is behind them: where a beam will land, where a drain will run, whether a wall is carrying load. We also inspect the basement and attic, test suspect materials and bring in trades or a structural engineer where needed. What we find shapes the plan and the price, instead of turning up as change orders after construction has started. You can see where this happens in our design-build process.

Planning a contingency

Even with careful investigation, some conditions only show up during demolition. A sensible budget for an older house carries a contingency: money set aside for unknowns, separate from allowances for finishes not yet chosen. The older the house and the more of it you open, the larger that reserve should be. Ask how contingency is tracked, who approves spending it and how you will be kept informed. Our budget planner adjusts its ranges for homes built before 1940, which gives a more realistic starting point.

Historic district review for exterior changes

Some City of Wilmington neighborhoods are locally designated historic districts. There, exterior changes visible from the street, such as windows, doors, porches, roofing, siding or additions, may need design review approval before a building permit is issued. Interior work generally is not reviewed. Some Pennsylvania municipalities have historic review boards of their own. Listing on the National Register of Historic Places alone generally doesn’t restrict a private owner using private funds; local designation is what usually brings review. We check a property’s status during feasibility and build any review time into the schedule.

Starting with your house

An older house rewards a patient approach: look first, plan around what you find, and keep the character that drew you to it. Our page on historic home remodeling describes how we work on these houses. When you are ready to talk about yours, request a consultation and we can begin with a walk-through.