Plaster Wall and Ceiling Repair in Madison, WI

Plaster repair in Madison: the short answer

Plaster is not drywall, and a drywall repair technique applied to it fails. Plaster over wood lath holds on by keys — ridges of plaster that squeezed through the gaps between the lath strips and hooked over behind them. When those keys break, the surface loses its grip whether or not it has cracked yet. Screwing a drywall patch straight into that lath pulls more plaster down inside the cavity and the drywall repair reopens within a season. The right sequence is: find where the sound plaster stops, secure what is left back to the lath, and then build the drywall patch out to the plaster's thickness rather than to drywall's.

That thickness difference is the detail most drywall contractors get wrong in Madison. Plaster over lath is usually thicker than half-inch drywall, so a drywall patch fixed flat to the studs sits shy of the surrounding surface and shows as a shadow line under any raking light. Building the drywall out to meet the plaster plane is not a refinement; it is the difference between a repair that disappears and one you can find from the doorway.

Why Madison has so much plaster and so little drywall in its oldest houses

17,310 Madison housing units — 13.0% of everything standing — were built in 1939 or earlier, and another 5,377 went up in the 1940s. Behind the paint in most of those is plaster over wood lath, not drywall. They are not scattered evenly either: they concentrate on and around the isthmus between Lake Mendota and Lake Monona, which carries three separate historic districts.

• Mansion Hill, northwest of the Capitol Square, holds the largest concentration of intact Victorian houses in Madison. In the nineteenth century it was where most of the city's large, ornate residences stood.
• Fourth Lake Ridge, on the Lake Mendota side of the isthmus, is mostly 1890s to 1930s houses, with a handful going back to the 1850s.
• Third Lake Ridge runs along the Lake Monona side.

Early Madison was described as a city of four hills: Capitol Hill, Mansion Hill, Third Lake Ridge and Fourth Lake Ridge. Three of the four are full of plaster walls, and the neighbourhoods that grew around them — Marquette and Williamson Street, Tenney-Lapham, Schenk-Atwood, Vilas, Regent — carry the same construction. If you live there, a contractor who quotes your job as a straight drywall repair has not looked at the wall.

None of which means drywall has no place in these houses. Most of them have had drywall put in somewhere already — a re-done kitchen, a finished attic, a bathroom stripped in the 1990s — so a single pre-1940 Madison house often needs plaster repair in one room and an ordinary drywall repair in the next. Establishing which is which, room by room, is the first thing that should happen on site.

Repair the plaster, or replace it with drywall?

Direct answer: repair what is sound, replace with drywall what has lost its keys, and be honest about which is which. Both are legitimate; the failure mode is choosing on price rather than on condition.

• Repair the plaster where the surface is cracked but still firmly attached, and on a wall in a historic-district house where the thickness, density and sound-deadening of the original are worth keeping. Isolated cracks, one failed patch, a corner — these are repairs, not drywall jobs.
• Replace with drywall where the keys have gone across a wide area, where a ceiling is sagging, or where earlier repairs have already put drywall in and the surface is a patchwork. A drywall patch built out to the plaster plane and fixed to framing rather than to lath alone is a permanent answer, and it is usually the cheaper one.
• Never skim over a bulging section and call it done. The bulge is plaster hanging off broken keys, and skimming drywall compound over it just adds weight to something already failing.

Ceilings deserve their own note. A plaster ceiling that has lost its keys is heavy and it comes down as a slab rather than as crumbs. If a plaster ceiling is sagging, keep out from under it and do not push it back up to see how loose it is. Those are the ones that most often end as a full drywall replacement, because a plaster ceiling that has started to let go rarely stops.

Whichever way it goes, the finish is the same problem as any other drywall repair in this city: the new surface has to match the old one. Pre-1940 Madison walls carry hand-applied plaster finishes rather than sprayed drywall texture, so the match is troweled rather than sprayed. See drywall texture matching for how that is established before anything is applied.