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Here at M Simpson & Sons Roofing Services we produce many roof estimates and reports. We often get asked what the various terms and phrases to do with roofing actually mean.

So you get a better understanding of the different components of a roof- We have put together this handy glossary:


ABUTMENT: A point where a section of roof meets another.

APEX: The highest point of a pitched roof. Also generally applies to a pitched section of roof

APRON: A lead flashing usually located at the front of a chimney which purpose is to protect the abutment between brick and roof.

BARGE BOARD: A length of material (usually plastic) which conceals the perimeter of the timber structure located along the apex.

BATTEN: A length of timber of which the roof tiles are fixed into place.

BROKEN BOND: A pattern in which the roof tiles are laid to ensure rainwater does not penetrate.

CLOAKING: A length of fibreboard which sits on the verge of the roof so that mortar can be applied onto to ensure sealant.

DOUBLE LAPPED TILE: Also known as “small tile” A more traditional covering that is usully made from concrete or clay. Most common in pre-war properties.

DRIP EDGE: A term used in flat roofing referring to the section where rainwater flows from the roof. Drainage is installed underneath. 

DRY RIDGE SYSTEM: A modern technique to ensure the fixing of ridges. An alternative to mortar. Also ensures ventilation to the top of the roof

DRY VERGE: A UPVC capping which ensures the roof verge is sealed. A modern alternative to mortar. 

EAVE: The lowest point of the roof. The purpose of the eaves is to keep rain water off the walls and to prevent the penetrarion of water where the roof meets the brickwork.

EAVE TRAYS: A section of plastic which prevents the sagging of underfelt at eaves level and subsequent ponding of water.   

EFFLORESCENCE: A white deposit found on concrete roof tiles. Also known as “lime bloom.” A natural result of the reaction between cement and water.

EPDM: Also known as “rubber roofing.” A type of synthetic rubber which is cold applied to flat roofs. Applied using a strong PVA glue. 

FASCIA: A section of material (usually plastic) which if fixed to the end of the rafter to which the guttering is fixed to. 

FELT MEMBRANES: A bitumen based material which is produced in rolls. Applied to flat roofs using heat guns. 

FIRRING STRIP: A length of timber which is thicker at one end to ensure the “taper” or “fall” of a flat roof.

FLASHING: Acts as a barrier against rainwater in joints on the roof or brickwork. Usually consisting of lead.

FLAUNCHING: A fillet of cement which is applied to the top of the chimney stack. Ensuring waterproofing and securement of protruding flues.

FLUE: A duct or pipe in a chimney for the extraction of gasses or solid fuel fume. Traditionally made from clay.

GABLE TILE: Also known as a “tile and half.” Is used to maintain the “broken bond pattern” when using double lapped tile. Usually used on roof verges.

GRP: “Glass Reinforced Plastic” is a paint on solution used on new flat roofing projects.

HIP TILE: A tile that is required where the roof changes direction or angle.

MORTAR: A workable substance consisting of sand and cement. Usually used to seal verges and traditional application of ridges.

OUTLET: A term referring to the drainage of rainwater. Materials ranging from lead to plastic. Can be located internally and externally of the property.

PITCH: The term of measurement which determines the fall of the roof. E.g. 20 degrees pitch. 

PITCHED ROOF: A sloping roof, most common on a typical house. Usually consisting of roof tiles.

PURLIN: A section of timber which is installed horizontally to form the structure of the roof to which the rafters are fixed to.

RAFTER: A length of timber that is sloped to form the structure of the roof. To where  battens are fixed in place.

RAINWATER GOODS: Ensures the drainage of rainwater away from the roof. Usually made from plastic or aluminium. Also known as “guttering.”

RIDGE TILE:  The top row of tile (usually round) that covers the highest point where the two pitched sections of roof meet.

ROOFLINE:  A term used to describe fascia and guttering systems 

ROOF TILE:  The first line of defence to keep rainwater out and heat in. They are traditionally made from locally available materials such as clay or concrete. 

SADDLE: A piece of lead which ensures waterproofing to where the ridge tile meets a chimney, gable end or other detail.

SILICONE: A workable substance used to seal gaps and lead flashings. Also known as “mastic.” Can also be used as a adhesive.

SINGLE LAPPED TILE: Also known as a “pan tile” A modern equivalent to single lapped tile usually made from concrete. Preferred by architects because of its labour and money saving properties.

SOAKER: A piece of lead that is installed underneath roof tiles to ensure waterproofing where abutments are located. 

SOFFIT: A section of material (usually plastic) which seals the underside where eave and rafters meet. The main purpose is to prevent the ingress of birds and insects.

TAPER: A phrase used in flat roofing which refers to the “fall” or “pitch” of the roof. Essential to ensure adequate water drainage. 

TILE VENT: A plastic tile which replaces a traditional. To ensure airflow through the roof space therefore decreasing risk of condensation.

UNDER-FELT: A roll of membrane that provided a layer of insulation and an extra waterproof barrier for any moisture that penetrates through the roof tiles. Modern products are ventilated.

VALLEY: The “V” shape where two sections of pitched roof meet ensuring rainwater flows away. Usually consists of lead or fiberglass. An area often prone to leaks. 

WATER CHECK: Usually a length of timber used in flat roofing to ensure water does not flow over the edge therefore protecting the fascia. 

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