Block Veneer Water Intrusion Inspection

In Moisture Intrusion by Morgan McClure

Typical of brick installation details CMU (concrete masonry unit) and split face block construction requires the same details for critical drainage between the back side of the block and the barrier material. Equally critical is proper flashing details in respect for such items as, but not limited to, potential leaking windows and doors, deck attachments, roof/wall interfacing details and other typical block penetration points.

As a result of a lack of proper flashing details as well as the lack of adequate drainage between the block and the barrier material water had penetrated into the wood based substrate and adjoining interior wall. What is important to note here is that barriers are not waterproof and DO NOT stop water from penetrating and damaging the barrier material itself. This photograph demonstrates what happens when water is retained between the mortor (mortor dam) and a barrier material.

Often during the process of constructing a masonry wall mortar can come into contact with the barrier material. When this occurs it creates a point where retained water can penetrate the barrier and pass into the interior structure.

It is critical that barriers are properly terminated into weep or drainage ports at any transition point. Note in the attached photograph how the barrier was installed before the steel lentil and only a small piece of barrier was placed over onto the lintel. This condition created a condition where draining moisture followed the path of the primary barrier past the transition point (lintel) and into the lower window head.