Conservatory Roof Repair and Replacement: What Are Your Options?

The Three Conservatory Roof Types and Their Failure Modes

Polycarbonate roofs. The most common type on Aylesbury's 1990s–2000s conservatories. Polycarbonate yellows and loses its thermal properties over 15–20 years. The failure mode at the perimeter is the gasket and glazing bar seal — when these fail, water tracks into the conservatory and can track behind the flashings at the house wall junction. The panels themselves rarely cause leaks; the fixings and seals do.

Glass roofs. Similar construction to polycarbonate but with glass panels in aluminium frames. The failure mode is seal failure at the glazing bars and at the ridge cap. Glass conservatory roofs are generally more durable than polycarbonate but more expensive to repair when components fail. Cracked glass panels are the acute failure mode.

Tiled roofs. A growing category — conservatories re-roofed with lightweight tiles on a timber frame. These are structurally closer to a normal pitched roof and have normal pitched roof failure modes: tile displacement, ridge mortar, and flashing failure. The junction with the house wall is still the critical point.

The House Wall Junction — Where Most Leaks Start

The junction between the conservatory roof and the house wall is waterproofed by a flashing that runs along the wall and underneath the conservatory roof edge. This flashing is typically lead or aluminium on better installations, or UPVC or sealant on cheaper ones. After 15–25 years, the sealant at this junction cracks and lifts; the lead or aluminium pulling away from the wall chase it was fixed into. Water tracks behind the flashing and enters the house at the base of the wall — often appearing as a damp patch inside the house proper rather than inside the conservatory.

The correct fix is re-dressing the junction flashing — removing the failed sealant, cleaning the surface, re-seating the flashing into the wall chase, and applying fresh sealant or wedge fixings. A temporary repair with silicone sealant over the existing flashing buys 12–24 months but doesn't address the root cause.

Conservatory Roof Replacement

Polycarbonate roof replacement with either better polycarbonate, glass, or lightweight tile is a specialist conservatory trade rather than a roofing trade. The structural implications depend on whether the existing frame can support the new roof weight — lightweight tile roofs require a structural assessment. We carry out the roofing element (flashings and house wall junction work) but the panel and frame replacement is typically contracted separately.