Importers should obtain ASTM-compliant test reports from an accredited third-party laboratory covering compressive strength, water absorption, and initial rate of absorption for the specific brick type. These reports serve dual purposes: supporting the HTS classification (which can vary by grade) and satisfying architect or general contractor specification requirements on US construction projects.

Refractory building materials are distinguished by their ability to withstand high temperatures — typically defined by pyrometric cone equivalent (PCE) ratings — and by their chemical composition (high alumina, silica, or basic chemistry). Standard clay bricks are classified by physical properties such as strength and absorption. The distinction matters for HTS classification and for determining whether antidumping or Section 301 measures apply to a given product.