Common Commercial Roofing Terms Explained

Posted on by Protech Roofing Team

Sometimes, it can be a little tricky trying to explain to tradesmen exactly what it is you want doing. You can be baffled with jargon and communication can break down. To avoid this happening to you, the team here at Protech Roofing have come up with a glossary of the most common roofing terms used in the industry, so you won’t need to panic and get flustered when next speaking to roofers.

Components common to pitched (sloping) and flat roofs:

Waterproofing: this is the outer surface which can be made from of a variety of materials, such as metal, slate, tile, wood or asphalt.
Felt/underlay: a thin waterproof layer, usually PVC sheeting or asphalt, laid on top of the rafters.
Void: the space between ceiling and roof surface.
Substrate: this is the surface that the roof is laid on, commonly timber decking. It is sometimes called sheathing, and is commonly made from plywood.
• Joists: horizontal supports.
Insulation: generally a thermal barrier but can also have acoustic or fire resistant properties.
Vapour Barrier: prevents the passage of moisture in the form of water vapour.
Flashings: pieces of lead sheet that form a waterproof cover to joints. They are often set into the mortar of walls and chimneys and then moulded to cover the surrounding surfaces.
• Nosing: flashing that is folded over at right angles around the roof edges.
Saddle: usually lead, moulded to fit over and protect a raised point of the roof.
Abutment: where a roof joins a wall that is higher than itself.
Cladding: overlapping roofing materials that form a weatherproof layer of protection.
• Parapet: a low wall running around the edge of a roof.


Styles of pitched roof:

Gable: generally two sided, with a flat wall at either end.
Hip: all the sides slope gently downwards to the walls.


Components particular to pitched roofs:

Ridge: the horizontal top of the roof. The ridge board runs underneath and anchors the joists. Ridge tiles are usually V-shaped and provide a waterproof top to the roof.
Truss: triangular frame that supports the roof.
Purling: a structural support for the roof situated midway along the roof void.
Fascia/Barge board: runs along the wall underneath the bottom of a sloping roof.
Battens: lightweight strips crossing the joists, horizontally, for anchoring slates or tiles.
Soffit: flat surface running underneath the fascia board, most visible from ground level.
Vents: allow ventilation into the void to avoid condensation, may be included in the soffits.
• Box end: neatly covers the fascia, soffit and bargeboard at the corners of the roof.
Eaves: the lower edge of a sloped roof, or the space that is often used for storage in loft conversions.
Dormer: the style of window that projects from a pitched roof.
• Rake: the edge of a gabled roof that reaches out past the wall of the house.
Valley: the joint between two sloping roofs.
Secret gutter: runs underneath the roof surface where two surfaces join.
Valley gutter: similar to the secret gutter but left exposed.


Metal Roofs:

Twin skin: two layers of metal with an insulating layer in the middle
Fully supported: used for copper, lead and zinc, the layer rests on a supported decking layer.
Flat, welted or angled seam: the edges of the adjoining sheets are folded up and then over together, angled or flat against the roof.
Standing seam: the edges are interlocked but left proud. The sheets can be slotted into place.
Batten seam: the join is wrapped around a batten of wood, fibreglass or plastic.
Seam sealant: waterproof mastic that forms an adhesive seal between the layers of metal.


Two main types of roof insulation:

Cold Roofs have the insulation at ceiling level, trapping heat below the roof void.
Warm Roofs are insulated above the roof void, close to the waterproof outer layer.

So now you’ve read our handy glossary full of the most common roofing terms you’ll hear, you’ll be able to go forward and speak more clearly and confidently to roofers, which will help you get the job done properly and smoothly!


commercial roofing sheffield

Here at Protech Roofing, our team of roofing experts are specialists in flat and pitched roofing as well as repairs and maintenance.


We have a many years of experience completing a wide variety of commercial roofing projects in Sheffield. View our case studies to find out more.






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