The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Care And Repair Of The House

Exterior Walls

1. REPAIRING CRACKS IN STUCCO

Since the use of stucco has become widespread there have been many unsatisfactory results in such work due principally to faulty construction and lack of knowledge as to proper methods of mixing and applying the material. Cracks are the most common defects found. They may be merely hair cracks, or may be large enough to admit moisture, which in turn may result in damage to the underlying structure and interior walls.

Hair cracks may be caused by using too rich a mixture or by employing inferior stucco material. They may also result from too rapid drying. Larger cracks are generally caused by settlement of the walls of the house or by some movement within them, as a result of improper foundations or poorly designed framing in the superstructure.

Stucco over brick, stone, or similar materials is liable to crack, especially around chimneys. The reason for this cracking is that the stucco has a different rate of expansion and contraction than the material that it covers, and a shearing stress or "crawling" effect takes place in the plane of contact between the two materials.

If cracks are unsightly and large enough to admit moisture, it is advisable to repair them. If, however, they are not very noticeable and seem to be doing no damage, it may be possible to postpone, repairs, since the plastered cracks may present a worse appearance than the open ones.

Tools.

A hammer, a sharp-edged and pointed instrument (such as a cold chisel or screw driver), a wire brush or whisk broom, a mixing board, a mason's trowel, and a water bucket.

Materials.

Portland cement, plastic cement, or Portland cement rendered plastic by the use of finely divided materials, clean sharp sand, and water.

Preparing the Cracks Before Pointing.

Before pointing, clean out the crackg thoroughly and chip them out to the shape of an inverted V so that the mortar may be keyed securely to the old work. The cracks should be brushed to remove all dust and loose particles and the cleaned surface and adjoining stucco dampened before new mortar is applied, so that the water in the mixture will not be absorbed.