What is Firebox?
The chamber that holds the burning fire, lined in brick or refractory panels. When those panels crack, we flag it as a fire-safety code violation on the report: heat can migrate through the breach to the combustible framing behind the wall. The panels have to match the spec for that fireplace make and model, and we verify that against the listing before signing off.
Related terms:Refractory PanelHearth