Key roofing terms in plain English. Understand what your roofer means so you can make informed decisions.
A condition where the nails holding roof tiles to battens corrode and fail, causing tiles to slip. Common on 1950s–70s concrete tile roofs where original galvanised nails have corroded after 50–70 years of London rain exposure.
An M-shaped roof where two opposing pitches meet at a concealed central valley. Common on Victorian terraces in Fulham, Kilburn and Willesden. All rainwater channels to this single valley — the most critical maintenance point.
Glass Reinforced Polyester — a seamless flat roof system where fibreglass mat is laminated with resin to create a rigid, watertight surface. Lasts 30–40 years, handles foot traffic. Preferred for West London extensions and balconies.
Classification for lead sheet thickness in roofing. Code 3 is 1.32mm, Code 4 is 1.8mm, Code 5 is 2.24mm. Code 4 minimum for flashings; Code 5 for valleys and flat areas. Defined by BS EN 12588.
Roofing underlay allowing water vapour to escape the roof space while blocking liquid water. Required under current Building Regulations on all re-roofing. Replaces traditional bitumen felt which traps condensation against timbers.
Removing and replacing mortar securing ridge tiles along the roof apex. Thermal expansion cracks the mortar over 15–25 years, allowing water in and eventually detaching tiles. Uses flexible sand-cement mix with plasticiser.
A concealed gutter behind a parapet wall on a terraced house. Invisible from ground level, it collects rainwater and directs it to internal downpipes. When it blocks or corrodes, water enters between floors before any external sign appears.
A designated area where planning controls preserve architectural character. Richmond has 73 conservation areas — the most in London. Roofing must use approved materials matching originals in material, colour and profile.
Call 0203 302 2547. No obligation.
0203 302 2547📞 Call Now: 0203 302 2547