Repurposing standard residential properties (Use Class C3) into registered children’s homes (Use Class C2) is one of the most litigated and risk-heavy stages of project development in the UK care sector. Misunderstanding the boundary between a standard household and an institutional care environment frequently results in planning delays, enforcement actions, and lost capital. This framework breaks down the definitive High Court precedents governing these classifications, details the precise operational thresholds that local planning authorities (LPAs) analyse to determine if a "material change of use" has occurred, and provides an actionable blueprint for structuring a successful Section 192 Lawful Development Certificate (LDC) application.