How can you achieve a watertight vertical expansion joint in a masonry wall? The joint surface usually is irregular because the mortar is slightly recessed from the surface at the edge of the bricks. Working the sealant into these irregularities is difficult, so voids remain at many of these mortar joints. How can I avoid this problem?
It is difficult to seal against an irregular surface. One way to create a straighter joint is to build the masonry against a removable foam filler. When the filler is removed, a smooth plane remains. If the surface is not too irregular, properly tooling the sealant joint can force the sealant into the imperfections and create an adequate seal. No matter how well the sealant joint is tooled, however, some water can usually bypass it through any bond separations in the masonry bed joint. Therefore, masonry walls should be designed so that any water that does leak through the sealant joints will be captured by through-wall flashing and directed out of the wall. Preformed expansion joint fillers are available that also can improve the water resistance.