Reference
Roofing Glossary: Plain-English Explanations
This glossary explains common roofing terms in plain English — from flashing and fall to warm roof and nail fatigue — so you can understand exactly what's on your quote or survey report.
Roofing quotes and reports are full of terms that make perfect sense to a roofer and mean very little to most homeowners. This glossary is here so you can look something up quickly and feel confident asking the right follow-up questions.
A–F
Batten — thin horizontal timber strips fixed across the rafters, to which tiles or slates are attached.
Cold roof — a flat roof construction where insulation sits below the structural deck, prone to condensation without careful ventilation. See our guide on warm roof vs cold roof.
Crazing — fine, web-like surface cracking, typically caused by UV degradation of an ageing felt covering.
Deck (roof deck) — the structural board or timber layer that roof coverings are fixed to.
Dormer — a structure projecting from a sloped roof, typically housing a window. See our dormer roofs guide.
EPDM — a synthetic rubber membrane used as a flat roof covering, known for flexibility and long lifespan. See our guide on GRP vs EPDM vs felt.
Fall — the slight slope built into a “flat” roof to allow water to drain rather than pool.
Flashing — weatherproof detailing, typically lead, sealing junctions between a roof and another structure such as a chimney. See our guide on chimney flashing problems.
Flaunching — the mortar bedding at the top of a chimney stack sealing around the base of the pots.
G–M
GRP — glass-reinforced plastic, a fibreglass flat roof covering applied as a liquid that cures into a seamless surface. Our recommended flat roof system.
Hip — the external angle formed where two roof slopes meet, running from ridge to eaves.
Lap — the overlap between adjacent tiles, slates, or sheets, essential for weatherproofing.
N–R
Nail fatigue — the corrosion and eventual failure of fixing nails over time, a common cause of slipped slates on older slate roofs even when the slate itself remains sound.
Ponding — standing water that remains on a flat roof surface rather than draining away.
Ridge — the horizontal line at the top of a pitched roof where two slopes meet, typically capped with ridge tiles. See our guide on ridge re-bedding.
S–Z
Sarking felt — the underlay layer fitted beneath roof tiles or slates, providing secondary weatherproofing.
Underlay — see sarking felt above; the secondary waterproof layer beneath the visible roof covering.
Upstand — a vertical raised edge, typically on a flat roof, where the covering turns up against a wall or parapet.
Valley — the internal angle where two roof slopes meet, channelling water from both slopes.
Warm roof — a flat roof construction where insulation sits above the structural deck, largely eliminating condensation risk. See our guide on warm roof vs cold roof.
If there’s a term on your quote or survey report that isn’t covered here, get in touch and we’ll explain it plainly — no question is too basic.
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