What procedure should be used to determine when substrate correction is necessary?

The correct procedure for determining when substrate correction is necessary is the use of the PCS, or Paint Chip Sample. The PCS is essential in assessing the lead content found in painted surfaces and their substrates. This procedure is used to identify the types and layers of materials that may contain lead and to evaluate the potential for lead exposure depending on the substrate's condition.

Understanding substrate correction is critical for accurately assessing lead risk, as different materials may require distinct considerations for lead abatement or remediation. The PCS allows for accurate analysis and helps ensure that any lead hazards are effectively identified and managed, providing a comprehensive understanding of potential risks associated with substrates in a property.

Other methods, though useful in their own right, do not serve the precise purpose of initiating substrate correction. Visual inspection might indicate the presence of lead but does not provide the detailed analysis that PCS does. Measurement accuracy pertains more to the precision of readings rather than the identification of when correction is needed. Subsample weight could assist in measuring total material but lacks the specificity required to make decisions about substrate handling. Thus, utilizing the PCS is the most effective and reliable approach to determining the need for substrate correction.