Understanding roofing terminology helps you make informed decisions and spot when a quote is over-specified or a defect is being oversold. Here are the terms Wilmslow homeowners most often ask us about.
- Nail Sickness
- The corrosion of steel nails fixing roof tiles, causing tiles to slip or displace. Common on Cheshire concrete-tile roofs built between 1965 and 1990.
- Flashing
- Strips of lead or other metal that seal the join between a roof surface and another element such as a chimney, wall or dormer, preventing water ingress.
- Valley
- The internal angle where two roof slopes meet, usually lined with lead to channel rainwater. A common failure point on period properties.
- Flaunching
- The mortar fillet around the base of a chimney pot that holds it in place and sheds water off the top of the stack.
- Repointing
- Renewing the mortar joints in brickwork or a chimney stack. Period stacks require lime mortar (NHL), not cement.
- Code 4 / Code 5 Lead
- A measure of lead sheet thickness. Code 4 (1.80mm) is the standard minimum for flashings and valleys; Code 5 (2.24mm) is used for longer or more exposed runs.
- Soffit
- The board fixed under the roof overhang, spanning from the fascia to the wall. Often ventilated to allow airflow into the roof void.
- Fascia
- The board fixed to the ends of the roof rafters, to which the guttering is attached.
- GRP
- Glass Reinforced Plastic, a seamless fibreglass flat-roof system with a 25-year design life. A modern alternative to felt.
- EPDM
- A synthetic rubber membrane for flat roofs, installed as a single sheet with a 30-50 year design life.
- Ridge
- The horizontal apex where two roof slopes meet at the top, capped with ridge tiles bedded in mortar or mechanically fixed.
- Hip
- The external angle where two roof slopes meet, running from the ridge down to the eaves, capped with hip tiles.
- Batten
- Horizontal timber strips fixed across the rafters to which tiles or slates are attached.
- Sarking / Underlay
- The membrane laid beneath the tiles or slates, providing a secondary barrier against water and wind-driven rain.
- Parapet Gutter
- A concealed gutter behind a parapet wall, common on Georgian and Victorian properties, usually lined with lead.
- Nib
- The small projection on the back of a plain tile that hooks over the batten. Nib failure causes tiles to slip.
- Patination Oil
- An oil applied to new lead to accelerate its protective patina and prevent white carbonate staining running onto tiles and brickwork.
- Dormer
- A structure projecting from a sloping roof, usually containing a window, with cheeks (sides) that require lead weatherproofing.
- Verge
- The edge of a roof at a gable end, where tiles or slates meet the gable wall, traditionally bedded in mortar.
- Tingle
- A metal clip used to secure a replacement slate where the original nail fixing cannot be accessed.