Penthouse flat

A penthouse flat is a top-floor unit in a residential block, typically with private rooftop terraces, larger floor plates and high-end finishes. Across Greater London, penthouse developments are common in regeneration areas such as King's Cross, Stratford and along the Thames in Westminster. Drainage characteristics include internal soil and waste branches connecting to the main building stack, plus extensive flat roof drainage carrying rainwater from terraces via internal rainwater pipes to ground level. Common issues include blockages of roof outlets by leaves and silt, leaks from terrace waterproofing through the floor slab into flats below, and complex pipework routing through ceiling voids that complicates leak diagnosis. Annual roof outlet maintenance is strongly recommended, and managing agents should hold detailed as-built drawings of the rooftop drainage to support insurance claims.