Evaluation of Exterior Masonry Wall for National Retailer
A large national retailer experienced extensive problems with the masonry walls at one of their Midwest stores. The building was constructed in 2003, and is comprised of single-wythe concrete masonry unit (CMU) walls supporting a steel truss/metal decking roof system. Masonry wall problems observed during the first several years of service included:
- an area exhibiting structural failure as evidenced by excessive outward bulging and cracking distress;
- multiple areas exhibiting cracking distress near corners and wall openings;
- multiple areas exhibiting CMU coating failure;
- multiple areas exhibiting deterioration of the CMU joint mortar; and
- multiple areas of exhibiting efflorescence/staining on wall surfaces
CTLGroup has considerable expertise in evaluating and resolving issues related to masonry construction, including those involving structural integrity, movements caused by material volume change effects or changes in soil support conditions, moisture/vapor transmission, thermal conductivity and coatings.
The owner asked CTLGroup to determine what caused the various observed masonry wall problems, and to develop recommendations for remediation.
Preliminary assessment of the failed wall area by CTLGroup led to the recommendation to immediately shore one of the roof truss girders bearing on the masonry wall in close proximity to the observed distress. CTLGroup conducted a thorough investigation including visual inspection, nondestructive testing, soil exploration and material sampling. Investigation findings and test results were documented and correlated to establish trends related to cause and effect. Samples of concrete masonry units, cell grout and joint mortar were extracted from the building and subject to laboratory examination. Material examination findings were used to confirm or refine causation mechanisms responsible for the observed masonry wall failure and deterioration.
Overall, the investigation required a comprehensive cross-section of CTLGroup’s expertise, including materials consulting, nondestructive testing (NDT), structural engineering and laboratory testing. Scientists and engineers at CTLGroup determined that the CMU wall problems had been caused by the combined effects of certain localized construction and material defects, none of which could be identified through visual inspection alone. CTLGroup subsequently provided the owner with specific remedial recommendations to address each of the noted masonry wall problems.