Glossary of roofing terms.

Barge boards - Batten - Counter batten - Dormer - Eaves - Fascia - Felt roof (Cold) - Felt roof (Hot) - Flashing - Flat Roof - Gable - Gauge - Hip - Hip board - Hip end - Margin - Nail sickness - Rafter - Ridge - Ridge board - Ridge tile - Sarking - Sarking board - Slate - Soffit - Tiles (interlocking) - Tiles (plain) - Tingle - Truss - Underfelt - Valley - Verge

A roof of a house

Barge boards: Decorative boards mounted under the roofing at a gable end - traditionally timber, nowadays usually uPVC. They may be mounted flash on the end wall or stood off on an overhanging framework with a soffit underneath.
Batten: A length of timber (usually tanalised, 40 x 20mm (1.5 x ¾ inch) sawn timber - but may vary according to roofing cover) mounted horizontally across the rafters to locate and/or secure the tiles or slates.
Counter batten: A batten mounted vertically up the roof along the lines of the rafters - normally used where the roof frame has been boarded to give a space when the underfelt and battens are fixed.
Dormer: A vertical window built into the slope of a pitched roof.
Eaves: The area just below the lower end of the roof - includes the fascia, soffit and guttering.
Fascia: The vertical board secured to the ends of the rafters under the lower end of the roof to which the guttering is normally fixed - traditionally timber, nowadays usually uPVC.
Felt roof - Cold: Normally a two or three layers system for boarded flat roofs using cold applied adhesive. Each layer has traditionally been bitumen based, however high performance polymer based materials are available which offer better performance. Usually for bitumen based materials, the first layer is just nailed to the roof boarding, the middle and top layers are glued with the top layer being covered in protective mineral chippings - should be good for at least 10 years.
Felt roof - Hot: Normally a two or three layers system for boarded flat roofs using hot bitumen or a flame torch. Each layer has traditionally been bitumen based, however high performance polymer based materials are available which offer better performance. Usually for bitumen based materials, all the layers are put down using hot bitumen or a flame torch with the top layer being covered in protective mineral chippings or painted with a solar reflective protective coating.
Flashing: A weather seal, usually lead or zinc, made where part of the roof abuts a vertical surface - one side of the flashing is normally embedded in a joint between two rows of bricks, the other side being shaped to fit onto the roof surface. Plain flashing is where the roof meets the vertical surface horizontally. Stepped flashing is where the roof meets the vertical surface at an angle - the steps in the flashing align with the joints of different courses in the brickwork
Flat Roof: A roof which has negligible slope, usually covered in felt, metal, or other material which is impermeable to water.
Gable: The vertical wall at the end of a pitched roof, an inverted 'V'.
Gauge: The measurement between the roof battens for positioning the slates or tiles, the minimum gauge is normally specified by the manufacturer/supplier - although a different meaning, the measurement is the same as the margin.
Hip: A sloping ridge formed by the junction of a pitched roof and a hip end.
Hip board: The board along the line of a hip from the fascia to the ridge of the pitch.
Hip end: A sloping end to a pitched roof which is covered with slates or tiles.
Margin: The exposed area of a slate or tile - usually the minimum is quoted by the manufacturer/supplier and may vary for a given slate/tile depending on slope of the roof and exposure - although a different meaning, the measurement is the same as the gauge..
Nail Sickness: Associated with slate roofs when the nails have corroded to such a state that they fail to hold the slates. Usually it starts with one or two displaced slates being observed but, as the whole roof was probably covered at the same time using the same type of nails, the problem is likely to get progressively worse.
Rafter: A vertical, sloping timber used to form the shape of the roof - the side of a truss.
Ridge: The horizontal line at the top of a pitched roof - applies whether there is a sloping roof on both sides (a Duo ridge), or if there is just one (a Mono ridge).
Ridge board: The horizontal board along the line of the ridge - normally along the top of the rafters or trusses.
Ridge tile: Normally a semicircular or angled tile used to seal the top of pitched roofs (and also hips). Usually the tile is secured by mortar and covers the fixings and top edge of the tiles/slates on both sides.
Sarking: Another name for roofing underfelt.
Sarking board: Used, where appropriate (i.e. required in Scotland, not in England or Wales) to board over the rafters for additional insulation.
Slate: Most UK supplies have come in the past from Wales, this is still available but pricey, in recent years Spanish slate has been imported at a lower cost, reclaimed Welsh slate is also available. Common sizes are 460x305mm and 610x355mm although other sizes may be available. Slates needs to be laid in a brick like bond with a double lap to avoid water entry around the sides, but even with this required double lap, they tend to be lighter per square metre than both plain and interlocking tiles. Slates do not have locating lugs (nibs) on the back (as do both types of tile) and so each slate needs to be individually positioned and nailed into place on the roofing battens, therefore roofing with slates can be more time consuming than either of the tiles. Usually suitable for pitched roofs with a slope of 23° or greater, larger slates can be used for even lower slopes. Alternatives to natural slate are manmade alternatives, some are lighter, most are cheaper.
Soffit: The horizontal board used to seal the space between the back of the fascia and the wall of the building - traditionally timber, or cement board nowadays usually uPVC with air vents.
Tiles - interlocking: Traditionally made from concrete with a profile allowing the tiles to overlap each other side to side, so giving much better protection from the ingress of water. Typically 380x230mm with an effective width of 200mm (i.e. 30mm overlap). They are normally laid in straight lines up the roof with a single lap. They tend to be heavier per square metre than slate but lighter than plain tiles. Locating lugs (nibs) on the back are used to mount then on the roofing battens. Usually suitable for pitched roofs with a slope of 23° or greater.
Tiles - plain: Traditionally made from clay, generally about 265x165. Need to be laid in a brick like bond with a double lap to avoid water entry around the sides, due to the required double lap, they tend to be heavier per square metre than both slate and interlocking tiles. Locating lugs (nibs) on the back are used to mount then on the roofing battens. Usually suitable for pitched roofs with a slope of 35° or greater.
Tingle: A small strip of lead, zinc or copper, nailed to the batten under a displaced slate, the slate is then replaced and the bottom of the tingle is bent up over the bottom edge of the slate and back onto the front surface to hold it in place. Usually a temporary repair for an old roof as their use can be a sign of 'nail sickness'.
Truss: Normally, factory made roof frame.
Underfelt: A layer of material between the back of the slate/tiles and the roof frame providing slight insulation and an extra waterproof barrier for any moisture. Traditionally made from bitumen with a strong woven base but this is liable to become brittle with age and rot where exposed to sunlight, modern alternatives are generally lighter and more durable.
Valley: The internal angle formed where adjacent pitched roofs meet. Traditionally zinc or lead sheeting was used on site to create a water channel downwards, nowadays preshaped valley channels are available.
Verge: The wall (or rafter) under the edge of a roof where it tops a gable end. The sides of the tiles down the verge were traditionally cemented, nowadays closing strips are available.