Wall Systems

Single Wythe: Reinforced Concrete Block

This efficient and economical masonry system allows a single layer of concrete block to serve as the structure and the exposed surface of the wall.

Single  Wythe: Reinforced Concrete Block
Truss attachment to bulb 'T' Flashing at base of wall

Recommended Building Types


Special Considerations

Definition and Assumptions

Units: Lightweight plain gray concrete block (CMU), 8" x 8" x 16"(nom.)

Reinforcement: #6 vertical reinforcement at 32" on center 9-gauge joint reinforcement at 16" o.c. (every other course)

Flashing: Base flashing and weeps

Mortar: Type N, Portland cement/lime, plain gray

Joints: Concave tooled

Regional Variations

Fire Rating (hours)

Ungrouted CMU: 2 hrs

Grouted at 32" on center: 3 hrs

Fully grouted CMU: 4 hrs

Sound Transmission Class (dB)

Ungrouted: 46.2

Grouted 32": 49.5

Fully grouted: 56.3

STC=(weight of wall)0.223x21.5

Wall Weight (lb/sq. ft.)

Ungrouted: 31 lb/sq. ft

Grouted 32": 42 lb/sq. ft

Fully grouted: 75 lb/sq. ft

Energy Rating

R-value: 2.3 (see note)


Outside Air =0.17
8 inch CMU 105 pcf, grouted at 32" o.c. =1.45
Interior Air =0.68
Total =2.3

Note: Adding insulation to the ungrouted cells raises the R-value from 2.3 to 4.65. If you need a greater R-value, add furring and rigid insulation to the inside face of the wall.

Green/LEED Rating

Design Tips

To make walls more weather resistant, consider the following:

Construction Tips