359. This consists chiefly in seeing that the work is performed in accordance with the specifications, and if the specifications are properly written much of the vexation of superintendence will be saved. The points which the superintendent should particularly inspect are the following:
Quality of Materials. - See that the laths are of the kind specified, and, if of wood, that they are free from bark and dead knots. If any such laths have been put on have them removed and clean, sound laths substituted. See that the lime is of the kind specified; if it is not in casks it will be well to require the plasterer to produce the bills for the lime; also that the lime is fresh and in good condition. Permit no lime that has commenced to slake to be used. Inspect the sand to see that it is free from earthy matter, and that it is properly screened. Make a note of the time the plasterer commences to make the mortar, and do not permit him to use it until it is at least seven days old, or as required by the specifications.
As to the proportions of the lime, sand and hair, not much can be told by the superintendent, unless he has the quantities measured in his presence, which will involve his being on the ground most of the time. Something, however, of the quality of the mortar and of the amount of hair may be determined by trying it with a trowel. The superintendent should endeavor to make himself familiar with the appearance of good mortar. See that the hair is mixed with the mortar at the stage specified, and in no case permit it to be mixed with the hot lime.
Lathing. - Before the workmen commence to put on the laths the architect or superintendent should carefully examine all grounds and furring to see that they are in the right place and are plumb and square. If the chimney-breasts are furred, as is the custom in the Eastern States, they should be tried with a carpenter's square to make sure that their external and internal angles are right angles; also see that all angles of partitions are made solid, so that there can be no lathing through the angles.
See that the end joints are broken at least every 18 inches; if the lather will do so, it is better to break joint in every course.
See that the laths over door and window heads extend at least to the next stud beyond the jamb (as in Fig. 238), so as to prevent cracks which are apt to appear at that point; also see that all the laths run in the same direction. When laths run in different directions (as in Fig. 239) cracks are sure to appear where the change takes place. See that all recesses in brick walls for pipes, etc., are covered with wire or expanded metal lathing, unless they are to be covered with boards.
Also see that all wood lintels and other solid timbers that are not furred are covered with metal lath. The juncture of wood with brickwork should also be covered with metal lathing. If any kind of metal lathing is used see that it is put up as directed by the manufacturers, and that all wire lathing is tightly stretched; see that the furrings are properly spaced and that the whole is well secured.
Before the plasterers commence work the superintendent should see that the building is closed in by the carpenter, either by filling the openings with boards, old sash or cloth. Cotton cloth is the best material for the purpose, as it permits of some circulation of air through it.
If the plastering is done in cold or freezing weather provision must be made for heating the building. Ordinary lime plaster is completely ruined by freezing and thawing, and plastering that has once been frozen will never become hard and solid.
When the scratch coat is partly on the superintendent should try to look behind the laths to see if the mortar has been well pushed through between them, as the clinch, or key, at the back of the laths, is all that holds the plaster in place.
See that the first coat is dry before the second is put on, if so specified; also that the surface of the brown coat is brought to a true plane, the angles made straight and square, the walls plumb and the ceilings level. The specifications should require that the first and second coats be carried to the floor, behind the base or wainscoting.
When brick walls are to be plastered the superintendent should remember that a much firmer job of plastering will be obtained if the wall is well wet just before the plastering is applied.
If the first and second coats have been properly put on the finish coat will need little superintendence beyond seeing that proper materials are used and that the work is well troweled, if hard finish.
If any of the improved plasters described in Sections 344-5 are used, the superintendent should see that the instructions furnished by the manufacturers are strictly followed, particularly as to the wetting of the laths and the proportion of sand used; he should also see that no mortar that has commenced to set is remixed. When machine-made lime mortar, or any of the hard plasters that are sold already mixed with sand and fibre, are specified, the care of superintendence will be greatly lessened. If improved plasters are used in freezing weather the building must be kept above the freezing point until the plaster has set.