This section is from the book "A Treatise On Architecture And Building Construction Vol2: Masonry. Carpentry. Joinery", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
21. It is the work of the joiner to apply the door and window casings, baseboards or skirtings, wainscoting, chair rails, paneled jambs, etc., and to hang the doors, sashes, transoms, etc., which fit into the openings he has trimmed or cased.
Grounds should be placed by the carpenter around the margins of all openings, along the lower edge of the side walls, and wherever necessary to secure any portion of the interior trim.
22. Architrave is a term given to a casing, having a back-band, used around door and window openings, and so placed as to conceal the joint between the wood ground and plaster. Thus in Fig. 27 (b), c is the architrave covering the ground a and plaster b. Architraves are sometimes richly molded or elaborately carved, but, except in specially designed work, it is considered better taste to keep them as simple and plain as possible.
23. Where casings extend to the floor, they must be thick enough to receive the end of the skirting c, or they may stand upon plinth blocks a, as shown in Fig. 21, which project beyond the casings and form both a base to the door trim and a stop for the skirting c. The architrave is attached to the ground a, Fig. 27 (b), after the plastering is thoroughly dry, and is so placed that its outside edge will extend well over and cover the joint between the plastering and the ground.
24. The upper corners of the architrave may be joined in several ways. They may be mitered, as shown at e, Fig. 27 (a), or, when the surfaces are plain, they may be butted, as shown in Fig. 27 (/). When the architrave consists of both plain and molded surfaces, it should be joined by both butted and mitered joints, as shown at (g). Sometimes, in cheap work, corner blocks are used to stop the trim against, as shown at (h). These, however, are not to be recommended, not only on account of their inartistic appearance, but also on account of their tendency to shrink and leave unsightly cracks on both sides of the doorway. The architraves should be securely nailed both to the ground and to the jamb or lining all around the opening.
25. The bases or skirtings of a room consist of a band composed of one or more boards from 6 inches to 18 inches wide, running around the bottom of the walls, to protect the plaster.
The skirting board may be plain, or it may have a molding worked on it, as at (a), Fig. 14, or it may consist of a plain board with moldings applied independently to give it a finish, as shown at (b), Fig. 14.
When the skirting is very wide, and is made up of more than one width of boards, it is sometimes desirable to have the lower member e project beyond the upper one, thus forming a sort of plinth around the room, as shown at c, Fig. 14 (b). The clearance at f should be from 1/8 inch to \ inch in rooms which are likely to be carpeted, as the edge of the carpets may then be pushed under it and secured to the floor. When floors are finished with parquet work, etc., the joint between the base and the floor should be as close as possible.