Brick veneer is a common exterior wall cladding for residential structures. Accounting for the veneer weight when designing headers over window, door and garage openings requires special considerations that are often overlooked. Typical 3 5/8″ thick veneer weighs approximately 40 lbs per square foot (psf) of wall surface covered. The results of inadequate design can be unsightly, as seen in Figures 1 and 2.
Figure 1. Vertical Veneer Crack Over Opening
Some design guidance is given in the International Residential Code (IRC). Table R301.7 in chapter 3 (IRC deflection criteria) specifies that the maximum vertical deflection for a lintel supporting masonry veneer cannot exceed L/600, where L is the span length (in inches) of the opening being spanned by the lintel. Section R703.8.3 gives lintel sizing and installation criteria (IRC lintel info). Lintel sizing is given in Table R703.8.3.1 and is based on the span of the opening along with the height of veneer being supported.
More detailed design guidance is given by the Brick Industry Association (BIA). BIA publishes many masonry design and construction resource documents. Their Technical Note 31B (Tech Note 31b) titled “Structural Steel Lintels” provides in-depth information to assist designers.
Veneer ‘arching’ is presented within the BIA Tech Note. If the veneer geometry is appropriate, arching is assumed to occur and the amount of veneer weight effectively transferred to the lintel/support is a pyramid shaped portion immediately above the support. Lacking arching, the load of the full veneer height may require consideration.
An additional vertical deflection requirement is provided in Tech Note 31B. Along with the L/600 vertical deflection limit (also specified in the IRC), the BIA document specifies an absolute maximum vertical deflection limit. That limit is 0.3″ under full loading. This is a serviceability limit meant to prevent cracking of the non-structural veneer. Therefore, the combined limit for the supporting member would be L/600, not to exceed 0.3″ (under total load conditions).
Final Comments: Failure to properly account for brick veneer in header design is a common problem. This can occur when the designer fails to recognize the veneer from a loading standpoint but also when the full deflection requirements are ignored/overlooked. Repairs after the structure is completed can be quite difficult.
Note that self supporting brick lintels are sometimes specified on project drawings. These could be steel channel sections, a steel beam with a ‘brick flange’ welded to the bottom beam flange, etc. Those members generally do not rely on the wall framing behind the veneer for support. For further assistance in design not detailed above, a design professional should be consulted.
Figure 2. Veneer Cracks Due to Excessive Deflection