If the walls are otherwise in good condition, minor cracks and places where mortar has fallen out may be repaired by an unskilled workman. If, however, a wall is badly cracked and crumbled beyond the aid of minor repairs, it may be necessary to engage an experienced workman to reconstruct all or part of the wall.
The minor repairs require the following tools and materials: hammer, sharp-edged and pointed instrument (such as a cold chisel or screw driver), wire brush or whisk broom, small mixing board, mason,s trowel, and water bucket; Portland cement, a finely divided material such as hydrated lime, clean sharp sand, and water.
Preparing Old Surfaces
Loose mortar between masonry courses should be chipped and picked out, and the joint brushed thoroughly to remove all dust and loose particles. The cleaned surface should be dampened before new mortar is applied to prevent absorption of water from the mixture.
To make repairs, a mixture of 1 part cement to 2 1/2 parts sand, or 1 part cement to 3 parts sand, is recommended in ordinary cases. However, a 1: 2 mixture is recommended for damp basements or those exposed to very moist conditions. A 1:2 mixture represents 1 part of portland cement to 2 parts of sand, measured by volume. The proportion to be used will depend entirely upon conditions, a larger proportion of cement being necessary in cases where excessive moisture prevails.
Enough water should be used to make a fairly dry mortar about the consistency of putty. The mortar should be thoroughly mixed and worked to insure best results. In filling cracks, the mortar should be applied like a calking material, that is, well-rammed and tamped in to form contact with all corners and depressions to make a complete bond. When the crack has been tightly packed, the surface should be smoothed off with a trowel. In pointing up joints in masonry, the mortar may be applied with a trowel, and the surface finished to conform with the old mortar.
After the material has hardened the new work should be kept wet for several days to increase the strength of the mortar. If work has been done on the outside of walls, they should be covered by tarpaulins to protect them from direct exposure to- the sun and drying winds.