Plain-English definitions of the roofing terms you'll come across when getting work done in Chippenham. Questions? Call 01249 247 076.
The corrosion and failure of the mild-steel nails fixing roof tiles, common on Chippenham's 1958–1978 concrete-tile estates (Hardenhuish, Stanley, Cocklebury). Once the nails fail, tiles slip across the slope and the roof needs re-fixing or replacement.
The mortar fillet at the top of a chimney stack that holds the pots in place and sheds rainwater. It cracks over time through frost and thermal movement, loosening the pots and letting water into the stack.
Milled lead sheet of 1.80mm thickness, the minimum specification for roof flashings such as those around chimneys and abutments.
Milled lead sheet of 2.24mm thickness, the minimum for valleys, parapet gutters, bay tops and exposed positions such as Chippenham's riverside streets.
Glass-reinforced polyester — a seamless, liquid-applied fibreglass flat-roofing system with a 25-year life, the standard replacement for failed felt roofs on Pewsham extensions.
A synthetic rubber single-ply membrane bonded as one sheet, suited to larger or more complex flat roofs where avoiding seams matters.
Natural Hydraulic Lime mortar — a breathable mortar mandatory on pre-1930 masonry and historic stacks, where hard cement would trap moisture and spall the soft brick or stone.
A mechanical, mortar-free system of clips fixed over the gable-edge tiles, compliant with BS 8612, that ends the cracked-and-dropping mortar problem on Chippenham's post-war estates.
A mechanically-fixed ridge system using a ventilated roll and screwed clamps instead of mortar bedding, meeting BS 5534 (2018) for wind uplift resistance and improving loft ventilation.
The internal angle where two roof slopes meet, lined with code 4 or 5 lead (or GRP), which channels rainwater off the roof; a common failure point on Chippenham's Victorian properties.
The fascia is the board along the roof's lower edge carrying the guttering; the soffit closes the underside of the eaves. On Chippenham's older estates the original timber is usually rotten behind the paint and replaced in ventilated uPVC.
An oil applied to new leadwork on completion to prevent white lead-carbonate staining washing onto the stone, brick or render below.
Last updated: August 2026