A primer on fixing plaster surfaces Consider their age, extent of damage when choosing repair

Home Work

October 18, 1998|By Karol V. Menzie and Ron Nodine

IF YOU LIVE in an old house, it's highly likely that you have plaster walls and ceilings. Most people love them -- they're a good, solid surface -- but they can pose problems if they're damaged. We get a lot of questions about dealing with various plaster problems, especially when it comes to replacing it.

But let's start with some plaster history. You can determine the approximate age of your home by the type of plaster and/or the way it's applied. If you have wood lath behind the plaster, your walls are probably built before 1930 or so. If there is horse hair in the brown coat (the layer under the white coat), the wall probably was built before 1900.

Most plaster used in the United States since the turn of the century is based on gypsum (the same thing Sheetrock is made of). Before then, walls were coated with lime-based plaster, which dates to the time of the pharaohs (it's on the walls of their tombs).

If you have what appears to be Sheetrock under your plaster you fall into a transition construction period, roughly 1930 to 1950. This material was called gyplath. It came in 2-by-4-foot sheets. It was easier and faster to install and easier to topcoat, so it replaced wood lath.

Finally someone realized it would be easier still to make larger sheets (these days they're usually 4 feet by 8 feet, or 4 feet by 12 feet) and finish just the seams, and that's the most common type of wall today, variously called Sheetrock, drywall or gypboard.

When it comes to repairing plaster, there are a number of options.

To patch a hole or crack in plaster that is otherwise in good condition, you can use plaster or joint compound (sometimes known as spackle or "mud"). To repair a crack, you must also apply joint tape. Joint tape can be paper (as used on Sheetrock seams) or fiberglass mesh, which is self-adhesive and easier to use.

The first step is to rake out the crack with a bottle opener, which will allow for better adhesion. Brush out any loose material and apply the tape or mesh. With a 6-inch trowel, cover the tape with joint compound, feathering the edge of the coating. When this coat dries, apply a second coat of mud with a 12-inch trowel. When this coat dries you can sand it smooth, then, if necessary, apply a third coat and sand again. Then you can paint it.

It requires a certain amount of skill to finish drywall smoothly. You can acquire the skill with practice, but if you don't want to do that, you'll need to hire a professional.

If the plaster is damaged beyond repair, you must either remove it and re-plaster or remove it and replace it with Sheetrock. Or you can laminate Sheetrock over the existing plaster.

Laminating is popular because removing plaster is not fun, and the dust will find its way into every corner of your house, no matter what precautions you take to prevent it. This is not to say you should not take them anyway, to minimize the dust as much as possible. (For instance, make

sure your forced-air heating or cooling system is off.)

And once the plaster is removed, you have to have it hauled away. (In most jurisdictions this is considered "construction debris" and can't be handled by regular garbage pickup. It's also amazingly heavy.)

Most old houses with plaster have 3/4 -inch baseboards, door and window casings. If you laminate with 1/4 -inch Sheetrock the moldings will still protrude beyond it. (Use 1/2 -inch Sheetrock on ceilings, so it won't sag.) Before you start on the walls, remove the cap molding on the baseboard and plan on replacing it later with new molding.

Find the studs or joists in the area to be laminated with a stud-finder or a hammer, so you can attach the new Sheetrock to them. Before you attach the Sheetrock, however, you should do any rewiring that's needed or upgrade energy efficiency with blown-in insulation. (If you want to use batt insulation, you'll have to remove the old plaster and lath.)

Glue and screw the Sheetrock over the plaster and finish it as usual. When they're painted, the walls and ceilings will look like new.

Ron Nodine is owner of American Renovator Inc., a Baltimore design-build remodeling firm, and president of the Remodelors Council of the Home Builders Association of Maryland. Karol Menzie is a feature writer for The Sun.

If you have questions, tips or experiences to share about working on houses, e-mail Ron at henovator.net or Karol at karol.menzialtsun.com. Or write c/o HOME WORK, The Sun, 501 N. Calvert St., Baltimore, Md. 21278. Questions of general interest will be answered in the column.

Pub Date: 10/18/98

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