Roofing terms explained: a plain-English glossary

Ridge. The horizontal line at the very top of a sloping roof, formed where two slopes come together and finished with ridge tiles.

Hip. The sloping line on a hipped roof where two neighbouring slopes meet, running down from the ridge to the gutter. Hip tiles cap it.

Verge. Where the roof stops at a gable end, along the sloping edge above the end wall. It takes the brunt of wind from the side, so its fixings matter.

Eaves. The bottom edge of each slope, where the roof overhangs the wall and carries the gutter.

Bedded and dry-fixed. On a bedded ridge the tiles sit in a mortar bed. A dry-fixed ridge or verge is held by clips and fittings, with no mortar doing the holding. BS 5534 was revised in 2014 and, since then, a ridge or hip held only by mortar has fallen out of favour, and a mechanical fixing goes in too. BS 8612:2018 is the standard that tests the dry-fixed versions. Our page on ridge tile repairs shows how the two methods look on a real roof.

Valley. The inside angle formed where two roof slopes lean toward each other and drain water downhill. It may be lined in lead, or made from tiles cut to meet along a line.

Flashing. A waterproof strip, usually lead, bent over the junction between the roof and anything standing up from it, such as a chimney, a party wall or a dormer cheek.

Soaker. A small folded sheet of lead or other metal slipped beneath each course of slates or tiles where the roof meets a wall, then turned up behind the flashing.

Flaunching. The sloping bed of mortar around the base of chimney pots, fixing them and throwing rain outwards.

Tingle. A little strip of lead or copper, nailed down and folded over the tail of a slate, used to hold a slate where no nail can go.

Lead code. The number that sets how thick a rolled sheet of lead is. Code 4 is 1.80 mm thick and weighs 20.41 kg per square metre, and Code 5 is 2.24 mm at 25.40 kg. Royston Lead recommends Code 3 for soakers only. Ask which code is going on your roof, and why.

Rafters. The sloping timbers that form the frame of a pitched roof. Every other layer is carried by them.

Sarking. Boarding or felt laid across the rafters beneath the battens, giving the roof a second line of defence if wind drives rain past the covering.

Underlay. The flexible sheet beneath the tiles or slates. It catches stray water, and some types also let moisture vapour out of the loft. Which type suits a roof depends on how the loft is ventilated, so ask your roofer what is planned and why.

Battens. Narrow timber laths nailed across the rafters. Every tile or slate hangs from one, and the gaps between them decide how much of each tile shows.

Headlap. The distance by which a slate or tile overlaps the course two rows below. A bigger overlap sheds water better on a shallower pitch.

Diminishing courses. Rows of stone or slate that shrink in size from eaves to ridge, with the biggest pieces at the bottom.

Horsham slabs. The thick, heavy local stone slabs found on older roofs around Horsham. Our page on Horsham stone roofing explains how such a roof is repaired.

EPDM. A synthetic rubber membrane supplied in a single sheet, usually stuck down to the deck beneath. GreenSpec puts its expected life at 20 to 30 years.

GRP. Glass reinforced plastic, also called fibreglass. It is laid wet in resin across boards and cures hard. Less gives 25 to 40 years as its typical life.

Torch-on felt. Layers of bitumen felt, the top one heated with a flame so it bonds to the one below. Less gives 10 to 20 years as a typical life, and notes that careful work can reach 20 years where a rushed job may fail in under 10.

Falls. The gentle slope built into a flat roof so water runs off it. BS 6229:2025 sets a minimum finished fall of 1:80, and roofers usually design steeper, around 1:40, so the finished roof still drains.

Upstand. The short upturn at the edge of a flat roof beside a wall or rooflight, there to stop water creeping behind it.

Our flat roofing page takes each of these coverings in turn.

Fascia. The board running along the edge of the eaves that the gutter is screwed to. It is the face you see from the street.

Soffit. The panel on the underside of the overhang, closing the space from the wall out to the fascia. Many soffits carry small vents so the loft can breathe.

Bargeboard. The timber running up the slope of a gable end and concealing the ends of the roof timbers. At the verge it does the job the fascia does at the eaves.

Rainwater goods. The collective name for gutters, downpipes and hoppers. Our page on gutters, soffits and fascias covers their repair and replacement.

If a word on your quote is missing here, put it to us at the survey and we will explain it using the photographs of your own roof. Our list of questions to ask a roofer shows what else to raise, and the rest of our work is on the Bognor Regis roofing page.