Rain Resistant Architectural Concrete Masonry

Integrally colored concrete masonry is commonly used as an architectural material in the Pacific Northwest. By combining different block sizes and shapes, colors or surface treatments, architects have designed many striking buildings. The interest in architectural block led to the development of industry recommendations for rain resistance. This updated technical note addresses the design and specification of a concrete masonry wall system for the western portion of the states of Washington and Oregon where rain resistance is a major concern. Some of these recommendations may not be applicable to the more arid regions of the Northwest.

This publication focuses on weather-exposed, single-wythe concrete block walls. These walls are assumed to be coated with a clear water repellent rather than an opaque coating for aesthetic reasons. They are designed as barrier walls and reinforced and grouted to withstand the forces of wind and earthquake, making the use of internal wall flashing impractical.