Box Gutter-

This is a horizontal gutter which is placed at the intersection of the parallel roof surfaces.

Copper Roofing-

Flat sheets of copper can be used as a roofing material which is very long lasting. The typical green colour of an older copper roof is due to a layer of oxidisation that protects the materials from further deterioration.

Dormer window-

This is a vertical window that is placed in a sloping roof.


The eaves are the lower part of a sloping roof that overhangs the walls.


A fascia is a board or other flat piece of material which covers the ends of rafters or other fittings.


These are a strip or sleeve of impervious material, non-ferrous metal or coated steel material that is formed to stop the entry of water.

Stepped Flashing-

These are flashings that seal the sloping edge of a roof against a masonry or brick wall.


A gable is the vertical, triangular end of a pitched roof. It is often a continuation of the wall it is sat on but it can also be made from different materials.


A girder is a large iron or steel beam or compound structure used for building bridges and the framework of large buildings.

Gutter Outlet-

This is an outlet for a gutter in a wall or parapet placed in order to allow water to drain off a roof.

Gutter Overflow-

This is an extra gutter outlet or scupper at a higher level than the normal outlet. It is used to safely direct the water outside if the main outlet gets blocked or is overloaded.


This is a term for the meeting point of two sloping roof surfaces.


An impervious material is one that doesn’t allow water to pass through, also known as waterproof or watertight.


In roofing terms, the lap is the amount by which slates, shingles, tiles and/or flashings overlap each other in order to achieve a waterproof seal. These are usually referred to as the ‘sidelap’ or ‘endlap’.

Moisture Barrier-

A moisture barrier is any material sheet or membrane that prevents or controls the amount of moisture, condensation or water vapour that enters the building.

Non Ferrous metal-

This is any metal including alloys that do not contain iron in any appreciable amount. These are used because they have certain useful properties, for example aluminium is low weight and zinc is resistant to corrosion.


A pantile is a traditional ‘S’ shaped roof tile which is usually made from clay or terracotta. These are useful as they are lighter than flat roof tiles and they can be laid on a lower pitched roof.


A parapet is the part of an exterior wall which is extended above the height of the roof surface in order to act as a safety precaution.


The pitch of a roof is the measure of its steepness, or slope.

Plastic Roofing-

These are roofing materials made specifically for patios, decks, extensions etc to allow varying amounts of light through the roof sheeting. They are made from synthetic materials for example polycarbonate or fibreglass.

Purlin- This can be either:

A horizontal roof beam made from steel or timber which sits on the principal rafter of a truss or propped on a wall to support the other rafters.  This is also known as an Under Purlin.

Or: A horizontal roof beam sitting on the rafters or on a truss or steel member that the roofing materials are directly fixed to. This is also known as an Over Purlin.


This is the highest point of a roof (The Apex) If there are two roof surfaces that are parallel then the ridge is a horizontal intersection of the two surfaces.

Roof Battens-

These are horizontal members that are fixed to the top of the rafters. The battens vary in size and spacing depending on the roofing material that they are carrying. In the larger sizes they are sometimes also known as Purlins.

Roof Vents-

These are a series of openings in a sealed roof that are used in order to ventilate the roof space.

Roof Verge-

This is the edge of a gable roof at the gable wall. Sometimes this will be flush with the wall and they often have an overhang.

Roofing Felt / Underlay-

This is a flexible water resistant membrane that is used beneath roofing and wall sheeting in order to collect and discharge any water or condensation. They are usually combined with reflective foil or other materials in order to give thermal insulation benefits.


A truss is a framework which typically consists of rafters, posts & struts. Its purpose is to support a roof, bridge or other structure.


A valley is the meeting point of two sloping roof surfaces that rainwater will run through on its way to the gutters.


This is a board or roll-formed metal section which is fixed at the gable in order to finish and protect the roof to gable wall joint.


A windbrace is a structural beam that stiffens a building against the forces of the wind. It can be made of timber or metal and is classed as a strut or a tie depending if the beam is in compression or tension.