Many of my working hours are spent envisioning how water will enter a building, in order to keep it out. While water can enter through deteriorated surface materials, most leaks occur at inadequately designed field joints. This is a quick look at various strategies for sealing joints. Gunk There are two basic forms of gunk used to seal joints: paint and caulking. Both are used too often and in the wrong places. For example, in many traditional exterior railings, the balusters sit on a lower rail, creating a joint that is sure to rot. The common solution is to paint the sucker and hope the paint will keep the water out. It will — until it cracks. Older paints on dense,
