Integral water repellents are usually polymeric liquid admixtures incorporated into concrete masonry units during manufacturing to reduce the wicking characteristics of the units. As such, they make masonry materials water resistant by limiting the amount of water penetration through the block.
They are particularly beneficial for use in colored architectural concrete masonry units where post-applied finished such as paints and other weather-resistant materials are not desired.
They are also beneficial for the use in masonry that is intended to receive weather-resistant finishes, as they significantly limit any water that does manage to get into the cores of the block from migrating to the interior of the building by wicking.
When used to mitigate water penetration, it is essential that integral water repellent admixtures be incorporated into the mortar at the jobsite, as well as into the block and any other masonry wall component to ensure adequate bond and similar reduced water wicking charateristics. A compatible water repellent admixture from the same manufacturer should be used in the mortar that was used in the block to ensure compatibility.
While these admixtures can limit the amount of water that can pass through units and mortar, they have little impact on moisture entering through relatively large cracks and voids in the wall. Therefore, even with the incorporation, proper detailing to prevent water entry and quality workmanship to ensure filled and adequate mortar joints is still essential.
Any water that does penetrate past the external surface of masonry with integral water repellents is more likely to quickly drain to the base of the wall because the units are not prone to retain it. So proper flashing and weep holes are critical to divert any water that finds its way into the masonry back to the outside.