Roofers use a lot of jargon. Here's what the common terms actually mean — in plain English, with local relevance for Farnham homeowners.
This glossary explains the roofing terms Farnham homeowners encounter most — nail sickness, flashing, pointing, valleys and more. Each definition is written in plain English so you can understand quotes and reports with confidence. For any question, call 0125 244 7622.
Any point where a roof slope meets a vertical surface such as a wall or chimney. Abutments are sealed with flashings and soakers. They're among the most leak-prone parts of any roof and the first place we check when diagnosing water ingress.
The decorative or protective board fixed to the sloping gable edge of a roof, covering the ends of the roof timbers. Bargeboards protect the roof structure from weather and, on period Farnham properties, often carry decorative Victorian detailing worth preserving.
The horizontal timber strips fixed across the rafters, to which tiles or slates are nailed. Battens must meet BS 5534 grading standards. During a full re-roof, all battens should be replaced rather than reused, as batten failure causes premature covering failure.
A damp-proof barrier built into a cavity wall above a roof junction, directing any penetrating water back to the outside. Missing or failed cavity trays cause damp where an extension roof abuts a wall — a subtle fault often misdiagnosed as a roof leak.
The capping course on top of a parapet or gable wall that sheds water and protects the masonry below. Coping stones and their joints must stay watertight; failed coping joints allow water into the wall head and are a common source of damp on parapet roofs.
A structure that projects vertically from a sloping roof, typically containing a window, creating usable headroom in a loft. Dormers have complex junctions requiring careful leadwork. Failed dormer flashings are a recurring source of leaks on Farnham's converted lofts.
Ethylene propylene diene monomer — a synthetic rubber membrane used for flat roofs. EPDM offers a 20–25 year lifespan, remains flexible in cold weather, and comes in large single sheets that minimise joints. A popular choice for larger flat roofs on Farnham extensions and garages.
The lowest edge of a roof, where it overhangs the exterior wall and the guttering is fixed. The eaves carry rainwater to the gutters and are a critical ventilation point for the roof space. Blocked eaves ventilation causes condensation and timber decay in the loft.
The board fixed along the lower edge of the roof, to which the guttering is attached. It caps the ends of the roof rafters and carries the weight of the gutters. Timber fascias on pre-1990 Farnham properties are a common source of rot once the paint fails.
The weatherproof material, usually lead, that seals the junctions where a roof meets a chimney, wall, valley or roof window. Correctly installed Code 4 or 5 lead flashing lasts 60–100 years. Most Farnham roof leaks trace back to failed flashings rather than the tiles themselves.
The mortar fillet at the top of a chimney stack that beds the chimney pots and sheds water away from the flue. Cracked or missing flaunching allows water into the stack and is a common repair on Farnham's period chimneys. It should be renewed in a suitable mortar mix.
Glass reinforced polyester, also called fibreglass — a cold-applied liquid system that cures into a fully seamless flat roof surface. GRP lasts 25–30 years with virtually no maintenance and is our standard recommendation for flat roofs on Farnham properties where budget allows.
The external angle where two roof slopes meet at a sloping edge, running from the ridge down to the eaves. Hip tiles cover this join. Like ridges, hips rely on sound mortar bedding, and open hip pointing is a common source of water ingress on older roofs.
A concrete or clay tile designed with side and head laps that interlock, allowing faster laying and lower pitches than plain tiles. Concrete interlocking tiles cover most of Farnham's post-war housing and typically reach end of life at 30–50 years as they carbonate.
The corrosion of iron or steel roofing nails over time, causing slates or tiles to slip even when the slates themselves remain sound. Common on Farnham's pre-1950 slate roofs, it's usually fixed by re-nailing with copper fixings rather than a full re-slate — a fraction of the cost.
The mortar finish applied to joints in brickwork and at roof ridges. On Farnham's Victorian and Edwardian properties, lime mortar must be used rather than cement — hard cement mortar cracks soft historic brickwork and causes spalling within a decade.
Standing water that fails to drain from a flat roof, usually caused by inadequate falls or a sagging deck. Ponding accelerates membrane deterioration and is the leading cause of flat roof failure. Correcting the fall is essential — no membrane survives permanent standing water.
A horizontal structural beam that supports the rafters across their span, part of the roof's load-bearing frame. Purlins carry the weight of the roof covering down to the supporting walls. Sagging purlins indicate structural issues found during a full roof inspection.
The sloping structural timbers that form the frame of a pitched roof, running from the ridge down to the eaves. Rafters carry the weight of the battens, underlay and tiles. Rafter-end rot, caused by leaking gutters, is one of the more costly repairs we encounter.
The horizontal apex line where two roof slopes meet at the top. Ridge tiles cap this join and are traditionally bedded in mortar, though dry-ridge systems now clip mechanically. Displaced ridge tiles after winter storms are a frequent call on Farnham's more exposed properties.
Boarding or membrane fixed over the rafters beneath the tiles, providing additional weatherproofing and rigidity. Common in Scotland and on exposed properties, sarking adds a robust secondary barrier. Its condition is assessed during any re-roofing survey on older properties.
A small piece of lead or other metal laid between individual tiles or slates at an abutment, working with the step flashing to weatherproof the junction. Soakers are hidden beneath the tiles and are renewed whenever step flashings are replaced at a wall or chimney.
The underside board that closes the gap between the roof edge and the exterior wall, beneath the fascia. Soffits are usually ventilated to allow airflow into the roof space. Rotten timber soffits on older Farnham homes allow water and pests into the roof structure.
A thin metal clip used to secure a replacement slate where the original nail fixing can't be reached. Tingles are a legitimate repair for individual slipped slates, but widespread tingle use signals nail sickness and a roof approaching the point of re-nailing.
A built-up roofing felt applied with a gas torch that melts the bitumen backing to bond layers together. It's the traditional flat roof material, lasting 15–20 years. Cheaper upfront than GRP or EPDM but with a shorter life and more seams that can fail.
The waterproof membrane laid beneath tiles or slates as a secondary barrier against water. Modern breathable underlay also allows moisture to escape the roof space. Failed or absent underlay is a common finding during re-roofing of older Farnham properties.
The internal angle where two roof slopes meet, channelling rainwater down to the gutter. Valleys are lined with lead or a preformed system. On tree-lined Farnham streets, valleys block with leaf debris every autumn — the most common cause of leaks we attend.
The edge of a roof at a gable end, where the tiles meet the outside wall. Verges are traditionally mortar-bedded but modern dry-verge systems clip mechanically. Failed verge pointing is a common entry point for wind-driven rain on exposed Farnham properties.
If there's a term on your quote you don't understand, just call and ask. We're happy to explain — no jargon, no pressure.
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