Each week we’re bringing you an in-depth look at one of the standard conditions we encounter and document during inspections of buildings and civil structures. 

Part 12: Hollow Areas

Hollow areas appear to have a void behind an intact surface based upon sounding with a mallet. Hollow areas are most commonly documented in masonry, plaster and stucco, but may also occur in architectural metal or wood.

Hammer-sounding a Guastavino tile ceiling

Although the surface is intact, hammer-sounding as part of a hands-on investigation can reveal material failures that are otherwise hidden. This can include failed fasteners in masonry and terra cotta, deterioration of back-up masonry, subflorescence in masonry, detachment from the substrate in plaster and stucco, and fastener failure or rot in wood.

Next in this series: Failed Coatings

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