The council approves extensions because planning law requires assessment against regulatory standards, not protection of neighbours' property values. Planners evaluate whether a proposal complies with local development plans, maintains adequate light, prevents excessive overlooking, and fits the area's character [1]. Under UK planning law, potential devaluation of a neighbouring property is explicitly not a material consideration—there is no legal right to an unobstructed view or to protection from market fluctuations. Even if an extension demonstrably reduces your home's value, that financial loss cannot be grounds for refusal. The council's role is to regulate physical development in the public interest, not to manage private financial disputes. If the extension breaches specific amenity standards—such as blocking significant light or creating privacy problems—those harms may support an objection, but mere economic devaluation will not. To assess your actual risk, consult a local surveyor or estate agent for a professional valuation.