Built-In Hazards: When Housekeeping Was Never Going to Fix It
An installation defect is distinguished from ordinary wear by its pattern and its timing. Wear develops along traffic paths and progresses gradually. A defect appears early, in a pattern following the work rather than the traffic: hollow-sounding tile across one bay, lippage along a single setter's run, a threshold proud from the day it was fitted.
Three references usually govern: the manufacturer's published installation instructions for the specific product, the applicable building code, and the contract documents and specification. Where the installer departed from the manufacturer's instruction, that departure is generally the most direct evidence available, because the instruction states plainly what was required for the product to perform as intended.
