Masonry Magazine July 1977 Page. 15
BIA Technical Notes
on Brick Construction
Brick Institute of America 1750 Old Meadow Road, McLean, Virginia 22101
7E
Sept/Oct
1976
COLORLESS COATINGS FOR BRICK MASONRY
INTRODUCTION
The successful performance of brick masonry walls depends upon the careful attention to three facets of the design and construction. They are:
1. Design-The selection of a suitable wall type and proper design and attention to details such as flashing, weep holes, coping, etc., so that the wall will function as intended.
2. Materials The selection of quality materials including brick, mortar, flashing and ties.
3. Workmanship-The execution of excellent workmanship characterized by the complete filling of all joints intended to receive mortar, their correct tooling, the proper installation of the flashing and weep holes as detailed, and a carefully executed clean-down procedure. Necessary parts of the workmanship, that are sometimes overlooked, are the careful batching of the mortar, proper storage of the materials and protection of the masonry work while it is under construction.
The results of the above will be masonry that is durable, strong, resistant to rain penetration and possesses the expected performance properties. Each of these elements is essential to satisfactory performance. Quality materials and quality workmanship will not compensate for poor design and detailing, and obviously, no design can compensate for poor workmanship or materials.
These three essential elements required for successful performance all to often are not achieved, resulting in brick masonry walls that have performance problems such as moisture penetration and/or the occurrence of efflorescence salts. Normally, the occurrence of such nonperformance requires remedial action which may include expensive and time-consuming additional work to alleviate the problem or problems. Unfortunately, there is a broad school of thought that believes and recommends the indiscriminate use of colorless liquid applications as waterproofers or water repellents to the brick masonry to solve these problems.
This Technical Notes discusses the use of such colorless liquid applications to brick masonry walls. The problems that may be incurred and the harm that may be done are also discussed. It does not cover the plant use of silicones or other solutions which may be applied to the units at the time of manufacturing, for the purpose of cleanliness of units during shipping and the control of initial rate of absorption (suction) of the units. This Technical Notes also addresses a recommended set of specific conditions where these types of colorless "waterproofers" might be used to advantage. A check list is offered as a recommended procedure for the evaluation of the conditions and situations for the use of these materials.
Other Technical Notes in this series discuss the selection of quality masonry materials, the design, proper detailing and selection of wall types, and the workmanship procedures to be used for the construction of a successfully performing brick masonry wall.
POSSIBLE DANGERS IN TREATMENT OF WALLS
The indiscriminate application of silicones and other clear penetrating sealer solutions to brick masonry can often cause more harm than good. Among the possible dangers are:
1. It will not stop moisture penetration through cracks or incompletely filled joints.
2. It could cause or contribute to spalling and/or disintegration of the brick units, by causing crystalline deposits of salts to form within the unit.
3. It will not completely stop staining and efflorescence, and may cover it sufficiently to prevent its removal.
4. It could make the wall nearly impossible to tuck point, if required.
The general recommendation of the Brick Institute of America, based on many years of experience and study, is not to use silicones or other clear penetrating solutions of similar ilk. If they must be used; they should be used only in specifically controlled and selected sets of circumstances and conditions, as outlined later in this Technical Notes.
MATERIALS AVAILABLE
Clear exterior masonry wall applications fall into several broad material groups, for example: silicones, stearates, gum waxes, acrylics, resins, rosins, rubbers, paraffins, butyls, oils, other polymers and various combinations of those mentioned. Although, they are usually called "waterproofers", they are not. They are water repellents, that is, these applications will when applied, change the capillary angle of the pores in the face of the masonry wall from positive (suction) to negative (repellency). In addition they will not, in the percentage strengths normally used, bridge nor fill hairline cracks or separations in the face of brick masonry walls. These hairline cracks, separations and poorly filled mortar joints are usually the principal source of moisture penetration and resulting efflorescence.