Plain-English explanations of the roofing terms Oxford homeowners encounter, with local relevance for Oxford's Victorian, Edwardian and post-war housing stock.
The corrosion of ferrous (iron) tile-fixing nails on roofs built in the 1950s-1970s. After 55-70 years the nails fail and tiles slip. It affects Oxford's post-war estates such as Blackbird Leys, Barton and Risinghurst widely, and is the most common trigger for full re-roofing.
A weatherproofing strip of rolled lead dressed into the junction between a roof surface and an abutment such as a chimney stack or wall. Lead flashing failure is the single most common cause of roof leaks on Oxford's Victorian and Edwardian properties, where original lead is now 100-130 years old.
The bedding mortar securing ridge tiles along the apex of a roof. On Oxford's 1930s properties this mortar is now 85-90 years old and eroding, causing loose ridge tiles and water ingress. Repointing a full ridge run on an Oxford semi typically costs between £350 and £650.
A concealed lead-lined gutter built behind a low parapet wall, common on the largest Edwardian villas in North Oxford and Summertown. Because they are hidden, parapet gutters block and fail silently, and internal damage can accumulate for years before it becomes visible.
Glass-Reinforced Plastic, a liquid-applied flat roofing material that cures to a seamless single membrane. GRP carries a 25-year warranty and has no joints to fail, making it the ideal replacement for the ageing felt flat roofs on Oxford's 1970s-1980s rear extensions.
Natural roofing slate from the Penrhyn and Ffestiniog quarries, used on Oxford's larger Victorian and Edwardian properties, particularly in the North Oxford Victorian Suburb. Welsh slate lasts 100-150 years and must be matched exactly in grade and colour for conservation area repairs.
A designated area where the character of the built environment is protected. Oxford has extensive conservation area coverage including Jericho, North Oxford, Old Headington and Iffley. Like-for-like roof repairs are permitted, but material changes on street-facing slopes require prior notification to the council.
Standard thicknesses of rolled lead sheet defined by British Standard BS EN 12588. Code 4 (1.8mm) is used for flashings and soakers; Code 5 (2.24mm) for valley linings and parapet gutters. Using the correct code is essential for a durable, compliant lead installation on Oxford roofs.
Need any of these explained for your property? Call our Oxford team on 0186 580 3181 for a free survey. Related reading: roofing advice blog.