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First Aid For The Ailing Houses

PLASTER

Plastering In frame construction, plaster is spread on lath nailed to the studding and other framework. If wood lath is used, it is separated by 1/4 to 3/6 inch between edges and ends. The first coat of plaster, mixed for strength and usually reinforced with hair or fiber, is applied with sufficient pressure for part of it to be forced between and behind the laths; it is through hardening there that the plaster is secured. Plaster does not adhere to lath or to other wood. Plaster binds itself to metal lath in the same way and is more firmly attached because of the greater number of openings through which it can pass.

Plaster attaches itself to plaster board and insulating board by penetrating the open texture of the surface and hardening in the pores.

Plasterboard ladi is made with 1/2-inch holes placed at intervals to hold the plaster more firmly. This type of lath material is nailed directly to the studs in sheets, with gaps of about 1/2 inch left between edges in order to provide for expansion and to give an extra grip for the first plaster coat.

The second coat of plaster, called the "brown coat," brings the wall to a level. The third coat gives a smooth surface and finish.

loose Plaster A dry plaster wall will last indefinitely. Plaster that is continuously wet for any long period, as would be the case from a leaking wall or roof or a dripping pipe connection, will be so softened that its attachment to the lath will fail; under this condition a ceiling may fall.

When part of a ceiling is seen to be bulged, the hand or a stick should be pressed against it to note signs of looseness; if the plaster moves under pressure, its contact with the lath has been broken, and there is danger that it will fall. The best remedy is to cut out the loosened plaster and to replace it with new, properly bonded to the ladi. For a temporary repair, or when appearance need not be considered, the loose plaster can be secured by a piece of plasterboard or wallboard nailed to the lath and the woodwork behind. Another plan is to draw the plaster back into place with slender flathead screws and tin washers, such as are used in applying roll roofing.

Plaster Cracks Since a plaster wall is thin and brittle, cracking will occur with any distortion of the frame that supports it, as may happen through settlement or the shrinkage of the woodwork. Such cracks will usually appear in corners or will run diagonally across a wall.