What’s in a roof? Jargon explained

Roofing is a skilled job.  It is also one that is full of specialised terminology.  We thought it might be helpful to explain the various components that make up a Redland roof system.

Dry Fix
Redland’s Dry Fix system is one of the main reasons that Redland roof systems are so reliable – but what is dry fix?

In order to remain weatherproof, it is obvious that the roof tiles need to be securely attached to the roof.  Roof tiles are 'hung' from the roof battens, with some (but not all) of the tiles being attached with nails.  The tiles are usually hung in parallel rows, with each row overlapping the row below it to exclude rainwater and to cover the nails that hold the row below.

The verge and ridge tiles (ie the tiles at the edges) need more secure fixing.  Traditionally these tiles were fixed using a mortar bed.  Mortar, however, is not always a reliable solution.  Difficult to get right in the first place, mortar is also liable to crack and crumble with age, leaving loose tiles and gaps in the roof that let rain in.

The National House Building Council (NHBC) is the body that provides warranties for new houses.  In 2010 more than half of claims against their Buildmark warranties related to pitched roofing with the vast majority of these problems relating to mortar failure on roofs.

Consequently, the NHBC now recommends dry fix systems.  As the name implies, dry-fix systems do not use mortar, but instead use mechanical fixings (screws and nails) to fix the tiles and associated weatherproofing.  The result is faster, cleaner and more effective.  That is why Redland’s dry fix is part of our roofing system.

Dry fix is only one of the terms you might encounter when considering a roofing project.  Here are a few more:

Battens: Roofing battens are used to provide the fixing point for roof tiles. They are generally laid at right angles to the trusses or rafters of a roof on top of the underlay.

Dormer Window: Window that projects out from the roof slope where there is a room inside the roof. You will probably have one or more of these if you are converting your loft

Eaves: The lowest point on the roof where water drains into the gutter. The timber running along the eaves is called the Fascia-Board

Fascia:  A vertical surface under the perimeter tiles. It joins the tiles to the soffit and is often used as a surface on which to fit gutters.

Finial: A decorative ornament, usually used to emphasise the apex of a gable or ridge.

Flashing: A thin, continuous piece of impervious material used in gulleys and on any angle or joint (such as around windows or chimneys) to prevent water getting in. Flashing was traditionally made of lead, but less hazardous and cheaper modern flashing is generally plastic.

Gable roofs:  A gable roof is the simplest form of roofing. Its most basic design is two flat slopes – often rectangles of the same size and pitch – joined together to create a ridge, or peak. The bottom edges of these slopes are the ‘eaves’. The term ‘gable’ describes the triangular-shaped part of the wall between the roof edges.

Hip: Where two roof slopes meet at an external angle.

Hipped roof: A hip roof, or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus it is a house with no gables or other vertical sides to the roof. A square hip roof is shaped like a pyramid.

Roof Tiles: Roof tiles are traditionally made from locally available materials such as clay or slate. Modern tiles are more likely to be made of concrete.  Coloured sands will be applied to the surface of the concrete so that the finished tile closely resembles its clay forebear.  Concrete is not only much cheaper than clay, but actually uses less energy in its manufacture as it does not need the high temperature firing process required by clay.

A large number of shapes  (or “profiles”) have evolved.  Go to the Find the right tile section to see the range of Redland profiles.

Ridge: Generally the highest point of a roof (or apex) where two slopes meet at a point

Side Abutment: Where a roof slope comes into horizontal contact with a wall or chimney

Soffit: The exposed undersurface of any exterior overhanging section of a roof eave.

Top Edge Abutment: Where a roof slope extends up to meet the underside of a chimney or dormer window. Or where a roof leans against a wall such as with a single storey extension ("lean-to").

Underlay / underfelt:  Underlay sits on the roof rafters, underneath the battens and tiles.  It provides a layer of insulation and an extra waterproof barrier for any moisture which gets under the roof covering.

Valley: Where two roof slopes meet an an internal angle. Water is channelled into this area from the slopes on either side and then down to the eaves. The valley is thus a critical part of the roof.

Verge: Where a roof slope oversails the outside wall of the building. The timber that often follows the line of the verge is called a barge board.

Vertical Tiling: Tiling to a vertical wall of a building.

Our Quick Tips

  • Check the cause of leaks carefully – you may be able to do a repair
  • A roof lasts for about 50 years
  • Try to replace the tiles like-for-like
  • Remember, a new roof will really revitalise your home
  • Don’t leave it too long – leaks cause havoc