Roofing Glossary
Plain-English definitions of the roofing terms you’ll come across when getting work done on a Horsham property.
- Nail sickness
- The corrosion and failure of the nails fixing roof tiles or slates, causing tiles to slip while remaining otherwise sound. Common on roofs 40–80 years old.
- Sarking felt
- The secondary weatherproofing underlay laid beneath tiles or slates. Also called roofing felt or roofing underlay. Modern installs use breathable membrane to BS 5534.
- Flashing
- Sheet material, usually lead, that seals the junction between the roof and an abutment such as a chimney, wall or valley to prevent water ingress.
- Verge
- The edge of a pitched roof at a gable end, where tiles meet the gable wall. Usually finished with mortar bedding or dry-verge systems.
- Valley
- The internal angle where two roof slopes meet, channelling rainwater. Lined with lead or GRP; a common leak point when liners fail.
- Ridge
- The horizontal apex where two roof slopes meet at the top. Capped with ridge tiles bedded in mortar or fixed with dry-ridge systems.
- Fascia
- The vertical board fixed to the lower roof edge that carries the guttering. Usually uPVC or timber.
- Soffit
- The horizontal board beneath the fascia, closing off the eaves and providing roof-space ventilation.
- EPDM
- Ethylene propylene diene monomer — a synthetic rubber sheet membrane used for flat roofs, valued for flexibility and longevity.
- GRP
- Glass-reinforced plastic (fibreglass) — a liquid-applied flat roof system that cures to a seamless, jointless surface with a 25-year guarantee.
- Pointing
- The mortar finish between bricks or in ridge and hip bedding. Repointing renews failed mortar to keep the roof and chimney weathertight.
- Flaunching
- The mortar bed on top of a chimney stack that seats the pots and sheds water. Cracked flaunching is a common cause of chimney leaks.
- Soaker
- A small piece of lead fitted under tiles at a wall abutment, working with step flashing to seal the junction.
- Batten
- The horizontal timber strips fixed across the rafters that tiles or slates are hung on. Spacing is set by the tile gauge.
- Underlay
- The breathable membrane laid over rafters and under battens, providing secondary protection against wind-driven rain.
- Code 5 lead
- A lead sheet thickness (2.24mm) specified as the minimum for most domestic valley and flashing work for durability.
- Dry ridge
- A mechanically fixed ridge system that clamps ridge tiles without mortar, meeting BS 5534 wind-uplift requirements.
- Tingle
- A metal clip used to secure a replacement slate where the original nail fixing cannot be remade.
- Hip
- The external angle where two roof slopes meet, running from ridge to eaves. Capped with hip tiles.
- Torching
- Traditional lime-mortar pointing applied under slates on older roofs; its failure leaves debris in the loft and signals age.
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