ABSTRACT
The application of waterproofing compounds to stonework or to old brickwork, especially if pointed or laid in lime mortar, should be done only after consultation with an expert technician, either an architect well versed in the subject, or a building scientist or consultant. Care must be taken to see that all work is pointed and that the walling is sound, before applying waterproofing liquids. The best of these preparations have a life of approximately five years, when the treatment must be renewed. They can sometimes be used with effect to waterproof porous window-sills and other projections, but the treatment should be renewed every three years. Much was expected of liquids containing silicone compounds. These are very successful for about three to six months, after which their efficacy is much reduced, and then is generally no better than the best of the older type of liquid waterproofers.
