This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
When pointing has to be adopted, the mortar should be raked out to tin-depth of about an inch, and fresh mortar inserted and finished in one of the ways just described. The square projecting pointings, known as tuck and bastard-tuck, furnish ledges for water, and are soon destroyed; they look neat, but should not be used. In exposed situations pointing should be done with hydraulic-lime or cement-mortar, or with mastic
In consequence of the difficulty experienced in getting the vertical joints of a wall thoroughly Hushed with mortar, it is a wise precaution to have the walls run with grout every two or three courses. This is a very thin mixture of lime or cement, fine sand, and water. Ordinary lime is of little or no use, and with hydraulic lime and cement the less sand that is used the better, as the sand tends to settle at the bottom of the pail, and the first part of each pouring may contain most of the lime or cement, and the latter part be nearly all sand. Certainly not more than its own bulk of sand should be mixed with the lime or cement. Besides consolidating and strengthening the wall, the grout has the merit of exposing defects in the jointing by escaping at the defective places, which are at once made good by the workman in order to stop the leakage.
Walls of concrete, rubble, and common brickwork are frequently covered externally with stucco. This practice is now more prevalent abroad than in our own country, but the practice is not by any means unknown among us. Formerly the matrix of the stucco was some kind of hydraulic lime, but nowadays Portland cement is almost invariably used, as it hardens better, and is more weatherproof and durable. The cement is made into mortar with two or three times its bulk of clean sharp sand, and applied to the wall as in ordinary plastering. The joints of the wall should be raked out to the depth of an inch to afford a kev for the stucco, and the wall should be well wetted before the mortar is applied, lest it should abstract the moisture from the mortar and prevent it hardening. The first coat is scored while wet, and afterwards finished with a second and somewhat richer coat. The whole may be coloured with Duresco, or ordinary oil paint
Fig. 63 Mortar-joins (full size).
At present stucco is out of fashion, but it has its uses, chiefly perhaps in the repair of old buildings; certainly it has rendered many a damp wall dry, and preserved much brickwork which would otherwise have perished.
Rough cast is a covering now seldom used for buildings as a whole, except in the case of cottages and farm buildings, but it is still occasionally adopted for the gables and some other portions of the upper parts of country houses and cottages It is executed by throwing a very thin paste of hot lime, coarse sand, and grit or fine gravel, upon a wet plastered surface. The whole requires an annual coat of limewash, which may be tinted with ochre or other colouring matter.