Both panel members agree that you have no automatic right to compensation from either the council or your neighbor simply because an approved extension reduces your property's market value. Planning permission focuses on land use and public interest, not private financial protection [1][2][3][4]. This is treated as external market risk rather than legal damage.

However, a narrow exception exists: if the extension constitutes a private nuisance—meaning it substantially and unreasonably interferes with your use or enjoyment of your property beyond mere aesthetics—you may have grounds for a civil claim. This would require proving severe, continuous interference such as blocking essential light, violating privacy, or creating hazardous conditions [1][5]. Your first step should be documenting the specific impact, discussing it with your neighbor, and checking whether the approved work actually violates any zoning or nuisance ordinances. If a violation exists, you could pursue damages for measurable property value loss, but this requires evidence of harm beyond visual impact alone.