Rear Gable Extension Completed in Leigh-on-Sea. This rear gable extension replaced a dilapidated conservatory with a usable garden room with level access bringing the outdoors in. DSB designed the scheme and obtained both planning and building regulations approval. DSB also obtained the build over agreement from Anglian Water which is required where building work is to take place close to or over the route of an existing public sewer or drain. Any development which includes new foundations, underpinning, piling or basements requires approval prior to commencement of the development.