How to Care for Plaster in an Old House

Interior design by David Kaplan. Photo by Anastassios Mentis

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    Save the plaster! This might have been the rallying cry of Julia Child, were she a preservationist rather than a chef.

    “Preserving nice plaster work, if possible, is always worth it,” reBUILD Workshop LLC President Themis Haralabides told Brownstoner. “After all, it is usually one of the reasons people like older houses in the first place.”

    Plaster walls and decorative details are high-quality, handmade finishes that give an old house character. They should not be replaced with inferior materials without a compelling reason. Plaster is worth preserving and, fortunately, easy to maintain — all you need is a little knowledge.

    Brooklyn Apartments for Rent Fort Greene 50 South Portland Avenue

    A Fort Greene Italianate brownstone with moldings in the parlor. Photo by Town Residential

    What is plaster

    Plaster is an ancient material that goes back at least to the Egyptians. Its exact composition has varied considerably through the ages, but in modern times it typically consists largely of plaster of Paris, otherwise known as gypsum.

    It is applied by hand and dries to a very hard finish that can last pretty much forever — as long as it isn’t damaged by water or cracked or separated from its underlying material by movement.

    Decorative, ornamental, and architectural plasterwork goes on top of flat plaster walls and ceilings. Examples include wall moldings, crown moldings, moldings on the ceiling, plaster medallions, and fanciful floral decorations or scrollwork just below crown moldings or on vestibule walls. The most elaborate plasterwork is usually found in the parlor.

    “In 19th century and early 20th century houses plaster work was a means to express social status,” said Haralabides. “The more ornate the plaster work, the wealthier the owner.”

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    Making molds for plaster medallions and other decorative details. Photo by Urban Plaster Restoration

    Advantages of plaster

    Plaster has many advantages over modern drywall. It provides better insulation, fireproofing and soundproofing than drywall. Also, unlike drywall, it will not harbor mold because mold cannot grow in it.

    Because it is hand applied by skilled artisans, it is a higher quality, more expensive material. When building a new house, real plaster walls are more expensive than drywall. But in an old home that already contains plaster, it is almost always more cost effective — and more attractive — for the homeowner to keep the plaster than replace it.

    “Plasterwork appeals to people who care about the long term quality of their interior,” plaster expert Jason K. of Urban Plaster Restoration told Brownstoner. “The material, as is the case with many other high-quality materials, has properties that can enhance an interior space in an aesthetic and physical manner. People feel better in a space in which quality plasterwork has been done. Additionally, quality plasterwork can be a boon to resale value, especially in a market where people prize preserved, pre-war detail,” he added.

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    Moldings can be created in place using a molding profile. Photo by Urban Plaster Restoration

    How to care for plaster

    If plaster walls and ceilings are in good condition — not cracked, peeling, or falling apart — you need not do a thing except paint. If there are nail holes or a few cracks, a painter can easily fix them.

    If damage is more extensive, Brownstoner recommends skim coating and more specific repairs by a skilled plaster expert. (See below for more details.)

    Plaster should not be removed and replaced by drywall, nor covered up by drywall. Covering makes spaces smaller and ruins the look of adjacent details such as moldings and door and window casings.

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    Restoring crown molding. Photo by Urban Plaster Restoration

    Avoid gut renovations

    If you value your plaster and original details, don’t gut. There is a great deal of misunderstanding about what a gut renovation is and when one is required. A gut renovation means removing everything down to the studs, including the plaster and lathe.

    Unfortunately, this will mean losing all the moldings — from baseboards to crown moldings — except possibly window and door casings. This looks unsightly in an old house, and the drywall that replaces the plaster will also look different (more flat) than plaster walls.

    A gut is not required to refresh tired finishes or upgrade mechanicals such as plumbing and electrical. A contractor can cut selective holes and channels in the plaster walls to swap out the mechanicals, then fill the holes with plaster or a combination of drywall and plaster. Electricians, for example, typically employ plaster specialists to close up walls after a whole-house electrical upgrade.

    Reasons for a full or partial gut could include water damage, extensive structural repairs, redoing tile in baths or kitchens, or moving walls to alter the floor plan.

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    Part of the ceiling has come down, revealing the underlying lathe. Photo by Urban Plaster Restoration

    How to skim coat plaster

    A skim coat leaves plaster in place but smooths the surface of walls and ceilings with three or more thin coats of plaster. Prices vary considerably, but typically start at about what you would pay for an extensive paint job and go up from there.

    When skim coating, a plaster (not drywall) expert can ensure a fine, smooth, level and durable finish that will easily take paint or wallpaper. After any repairs are completed, plasterers typically begin by applying a thin layer of bonding material such as pink-colored Plaster-Weld, then a layer of fiberglass mesh, followed by three or more very thin layers of plaster skim coating. The layer of mesh ensures the plaster does not crack months later.

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    The pink layer is Plaster-Weld. Photo by Urban Plaster Restoration

    Repairing holes

    It is acceptable to patch large holes with drywall, topped by thin layers of skim coated plaster to blend the repair into the rest of the plaster walls. Alternatively, a plaster expert may elect to fill the hole with an underlying substrate such as lathe, followed by a scratch coat of plaster and several more thinner layers of plaster on top of that.

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    Re-creating missing plaster details. Photo by Urban Plaster Restoration

    Repairing sagging plaster

    When a section of plaster has separated from the underlying lathe but is otherwise intact, a plaster expert can reattach the plaster using plaster pins, then skim coat over the pins so they are not visible. If the separation occurs on a ceiling, the problem should be attended to immediately, to prevent a dangerous collapse.

    “These ceiling cave-ins can be prevented before they become a potentially dangerous problem by a procedure called “pinning,” said Jason K. “Pinning is a landmark conservation technique whereby the plaster is pinned back to the ceiling joist.”

    Making a ceiling perfectly flat and stable is one of the more skilled and costly types of plaster repair.

    Repairing damaged plaster details

    If decorative plaster details are broken, missing or melted, a plaster expert can reproduce them exactly using molds, forms or freehand techniques. This kind of work requires advanced skills and can be more expensive than skim coating.

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    The elaborate ceiling restored. Photo by Urban Plaster Restoration

    When to hire a plaster expert

    Brownstoner recommends hiring a plaster specialist to handle skim coating, significant repairs, and decorative plaster details. (The typical contractor employs workers skilled with drywall construction, not plaster specialists.)

    A plaster expert can create perfectly smooth, level, and durable surfaces that will easily take paint or wallpaper. Transitions to adjacent surfaces such as moldings will be appropriate and attractive. Plaster experts will not need to sand as often and will create less dust than other workers.

    They have specialized materials and equipment, including extra-thick rosin paper and modular interior scaffolding, to protect homes and speed their work.

    Someone skilled only with drywall, on the other hand, can damage homes with walls that are not straight or that crack all over six months later.

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