Installing base and ceiling mouldings
Base moulding serves as a finish between the finished wall and floor. It is available in several widths and forms. Two-piece base consists of a baseboard topped with a small base cap (figure A).
When plaster is not straight and true, the small base moulding will conform more closely to the variations than will the wider base alone. A common size for this type of baseboard is 5/8 by 3 1/4 inches or wider. One-piece base varies in size from 7/16 by 2 1/4 inches to 1/2 by 3 1/4 inches and wider (figures B and C).
Although a wood member is desirable at the junction of the wall and carpeting to serve as a protective "bumper," wood trim is sometimes eliminated entirely.
Most baseboards are finished with a base shoe, 1/2 by 3/4 inch in size (figures A, B, and C). A single-base moulding without the shoe is sometimes placed at the wall-floor junction, especially where carpeting might be used.
Installation of Base Moulding
Square-edged baseboard should be installed with a butt joint at inside corners and a mitered joint at outside corners (figure D).
It should be nailed to each stud with two eightpenny finishing nails. Moulded single-piece base, base mouldings, and base shoe should have a coped joint at inside corners and a mitered joint at outside corners.
A coped joint is one in which the first piece is square-cut against the plaster or base and the second moulding coped. This is accomplished by sawing a 45 degree miter cut and with a coping saw trimming the moulding along the inner line of the miter (figure E).
The base shoe should be nailed into the subfloor with long slender nails and not into the baseboard itself. Thus, if there is a small amount of shrinkage of the joists, no opening will occur under the shoe.
Ceiling mouldings are sometimes used at the junction of wall and ceiling for an architectural effect or to terminate dry-wall paneling of gypsum board or wood (figure A).
As in the base mouldings, inside corners should also be cope-jointed. This insures a tight joint and retains a good fit if there are minor moisture changes.
A cutback edge at the outside of the moulding will partially conceal any unevenness of the plaster and make painting easier where there are color changes (figure B). For gypsum dry-wall construction, a small simple moulding might be desirable (figure C).
Finish nails should be driven into the upper wallplates and also into the ceiling joists for large moldings when possible.
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