Question answered
Roofing terms explained: a plain-English glossary
The short answer
A roof is a set of named parts. The ridge is the top line and hips are the sloping outside corners. Verges edge the gable ends, valleys are the inside corners, and eaves are the lower edge, with the fascia and soffit beneath. Flashings, soakers and flaunching seal the joins, while battens and underlay sit below the tiles or slates and carry them.
Quotes and survey notes are full of trade words. Here is what each part of a roof is called, what it does, and where water tends to get past it.
The lines of the roof: ridge, hip, verge and valley
The ridge is the level line along the top, where the two main slopes come together. Ridge tiles cover it, and on an exposed coast they carry fixings beneath the mortar; see ridge tile repairs.
A hip runs down the outside corner of a hipped roof, from the ridge to the eaves. So a hipped bungalow shows one ridge and four hips, each finished with a line of specially shaped tiles.
The verge finishes the slope at a gable wall. Wind pushes hardest on this edge, so how it is fixed matters. A valley is the reverse of a hip: an inside corner where two slopes drain into one channel, lined with lead or a liner. A blocked or split valley is a frequent source of leaks.
The way these lines combine depends on the house. Our pitched roofing page shows the common forms, and the guide to Worthing house roofs shows which suit which homes.
The edge of the roof: eaves, fascia, soffit and gutter
The eaves are the low edge, where the slope ends above the wall. The tiles or slates normally overhang a little, so water drips clear of the brickwork.
The fascia is the face-board running along the rafter ends; the gutter normally screws to it. The soffit sits beneath the overhang, closing it off from below, and it often carries vents, because air entering at the eaves keeps a cold roof space ventilated, as BS 5250 sets out in Marley's guidance on ventilating a cold roof.
The gutter gathers the run-off and carries it to the downpipe. Makers want the run to slope slightly to its outlet, between about 1:600 and 1:350 depending on the system, which is why a sagging run holds water. Our gutters, soffits and fascias page covers the whole roofline.
Soft or stained timber at the eaves often tells a surveyor a gutter has been spilling for some time.
Sealing the joins: flashing, soaker and flaunching
A flashing is a strip of waterproof metal, usually lead, that seals the junction of roof and wall or stack. A soaker is a short L-shaped lead sheet slipped under each tile or slate along that junction, so water runs over it and not behind. Leadworx lists code 3 sheet for soakers only, and says code 4 has become the usual choice for general flashing.
The lead code describes the sheet's thickness and weight, so a higher number means heavier lead. Our lead roofing page goes into the detail.
Flaunching is the sloping mortar bed at the top of a chimney stack around the base of the pots, shaped to throw rain away from them. Once it cracks, water finds its way into the stack. The chimney flaunching page explains the repair, and the chimney repairs hub covers the rest of the stack.
Under the covering: battens, underlay and pitch
The tiles or slates you see are only the outer layer. Battens are thin timbers across the rafters, and tiles or slates hang from them. Underlay is the membrane stretched beneath, which catches wind-blown rain and condensation and guides it towards the gutter. On older roofs it can be missing or torn, so a survey checks it from the loft.
Pitch simply means how steep the roof is, and every covering has a minimum. Defer to the product data sheet: A Marley concrete plain tile needs at least 35 degrees, while natural slate under BS 5534 starts at 20 degrees (moderate exposure, 115 mm headlap). For slate, see slate roofing.
A flat roof, in Approved Document J's wording, is one with a pitch below 10 degrees. It still needs falls so water drains: IKO, citing BS 6229, advises designing for 1:40 so the finished roof achieves at least 1:80. The flat roofing page covers the materials.
Windows in the roof: rooflight or roof window
People say skylight for both, but the Building Regulations draw a line. A rooflight in Approved Document L is glazing set on a kerb or upstand, standing proud of the roof surface. A roof window is built into the slope, sitting level with the tiles that surround it.
The difference matters in practice. For a new or replacement element in an existing dwelling, Table 4.2 gives rooflights a limit of 2.2 W/m²K. Roof windows must reach 1.4 W/m²K, or alternatively Window Energy Rating Band B. Fitting details and cost are on the skylights and roof windows page.
Whether a change needs consent is a separate question, answered in the roof planning permission guide.
Once the words are familiar, a written quote reads more easily. If you are weighing several, how many roofing quotes to ask for is a useful read. A local roofer can also talk you through the terms on site, and the same words help you write a clear complaint; see how to complain about a roofer. Our home page links to every service.
Two more roofing words, answered
Why do roofers talk about lead code?
The range runs from code 3 to code 8, 1.32 mm to 3.55 mm thick, and the number tells you the weight and the job it suits. Code 3 is for soakers only, code 4 is the usual choice for flashings, and heavier codes go on larger or more exposed areas.
What does a minimum pitch mean for a new covering?
It is the shallowest slope a tile or slate is designed to shed water on. Below it, wind-driven rain can pass under the laps. Marley publishes a figure for each tile, so a re-cover on a low slope may need a different product from the original.
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