The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
First Aid For The Ailing Houses
Many fine hairline cracks, known as "fire cracks," can be filled by brushing with a mixture of 3 parts boiled linseed oil and 1 part turpentine, or for somewhat wider cracks with white lead thinned with turpentine to a fairly thin paste; this is rubbed on with a cloth to force the paste into the cracks, and the excess is wiped from the surface. Light sandpapering may be required when the paste has dried.
Sometimes a crack occurs in a wall at the corner of the room- This repair is difficult for an amateur, but can be done by cutting away a 6-inch-wide strip of plaster from each side to the comer, running the full length. A strip of corner lath is then nailed in place and the corner replastered. An alternative to corner lath would be flat sheets of metal lath, cut into strips 12 inches wide and bent at right angles to fit into the corner. Replastering follows.
Cracking along a vertical line from floor to ceiling often occurs when the plaster has been placed over plaster board or wallboard. The problem is that the joints between the sheets were not properly filled. The only sure cure is to refill the joints (see section on Wallboards).
Sometimes, either by location of the house or shoddy construction, cracks will appear in plaster walls simply from vibration. Houses located near airports, close to highways where heavy trucking rumbles by, or near a railroad, are naturally susceptible. Since plaster is a material with absolutely no "give" to it, the slightest shaking will cause it to crack. In serious cases, it may even be so loosened that it can fall off the walls and ceilings in chunks. Such a location for a house demands construction much sturdier than will be the case where such vibration is not a factor.
Plaster on wood lath will sometimes develop dark marks corresponding to the laths. These marks are likely to be found on ceilings beneath unheated attics. In this situation the plaster becomes chilled, and there is condensation as the damp house air comes into contact with it. With the plaster thus dampened, dust is absorbed by it, and the plaster becomes darkened. Spaces between the laths are less affected than the plaster over the lath, because the plaster at that point dries out more quickly. Lath marks will not occur on a ceiling under a cold attic when the ceiling is protected by insulation.
Dark marks on a plaster ceiling may be painted out with water-emulsion paint matched to the ceiling color. The marks will appear again, however, unless the original condition has been remedied. The same method may be used for the rust stains caused by leaks.
