If you have ever read a roofing quote or a surveyor’s report and wondered what half the words meant, you are not alone. Roofing has its own vocabulary, and the same part can go by two or three names depending on who you ask. Knowing the main parts of a roof makes it much easier to understand what a roofer is proposing, spot problems early and compare quotes properly.
This guide explains the parts of a roof in plain English, from the timbers that hold it up to the tiles and trims that keep the weather out. It covers a typical UK pitched roof, which is the most common type on British homes.
The Roof Structure: What Holds It Up
Rafters
Rafters are the sloping timbers that run from the top of the roof down to the walls. They carry the weight of the battens, tiles and anything else on top. On a traditional roof, rafters are cut and fitted on site.
Roof Trusses
Most modern houses use trussed rafters, which are factory-made triangular frames, usually in a W or N shape. They are lifted into place and fixed to the walls, and they span the whole width of the house without needing support from the middle. A trussed roof is quicker to build, but the timbers inside should never be cut or removed without advice from a structural engineer.
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Ceiling Joists
Joists are the horizontal timbers that carry the ceiling and floor of the loft. On a traditional cut roof, they also tie the bottom of the rafters together so the roof does not push the walls outwards.
Ridge Board
The ridge board is the horizontal timber at the very top of a traditional roof, where the rafters from both sides meet.
Purlins
Purlins are horizontal timbers that run along the roof slope and support the middle of the rafters. They are common on older and larger cut roofs where the rafters need extra support.
Wall Plate
The wall plate is a timber laid along the top of the wall. The rafters or trusses sit on it, and it spreads the load evenly across the brickwork.
Collar Ties and Struts
Collar ties join pairs of rafters near the top to stop them from spreading. Struts are angled timbers that carry the weight of the purlins down to the walls below.
The Roof Covering: What Keeps the Rain Out
Tiles or Slates
The visible outer layer of the roof. Tiles and slates overlap each other so that water runs off from one to the next. To compare the options, see our guide to the types of roof tiles.
Battens
Battens are thin timber strips fixed across the rafters, and the tiles or slates hook or nail onto them. Their spacing has to match the size of the tile. Our guide to roof battens explains how they work.
Underlay
Underlay, also called roofing felt or breathable membrane, sits under the battens. It catches any water or wind-blown snow that gets under the tiles and lets it run down into the gutter. See roof felt and underlay for the main types.
The Edges and Joints of a Roof
Ridge
The ridge is the horizontal line at the very top where two roof slopes meet. It is covered with ridge tiles, which can be bedded in mortar or fixed with a dry system. Our article on dry ridge and ridge tiles explains the difference.
Hip
A hip is the sloping line where two roof slopes meet at an outside corner. Hip roofs have four slopes and no gable ends. You can read more in our hip roof guide.
Valley
A valley is the internal angle where two slopes meet, forming a channel that carries water down the roof. Valleys are lined with lead or other materials, and they are a common leak point. Read more in our guide to roof valleys and guttering.
Verge
The verge is the sloping edge of the roof at a gable end. It is finished with mortar or with a dry verge system, and it needs to be well fixed because wind can lift it.
Gable
The gable is the triangular section of wall at the end of a pitched roof, between the sloping edges. Our guide on what a gable end is covers it in more detail.
Eaves
The eaves are the lower edge of the roof, where it overhangs the wall. Our guide on what eaves are explains why this part matters so much.
Fascia, Soffit and Bargeboard
- Fascia: the board fixed along the ends of the rafters at the eaves. The gutters are normally attached to it.
- Soffit: the board under the eaves that closes the gap between the fascia and the wall.
- Bargeboard: the board fixed along the verge at a gable end, sometimes called a barge board or verge board.
Drainage, Flashings and Fittings
- Gutter: the channel at the eaves that collects rainwater from the roof.
- Downpipe: the vertical pipe that carries water from the gutter to the drain.
- Flashing: strips of lead or other metal that seal the joints between the roof and walls, chimneys and other details.
- Chimney stack: the structure that rises through the roof, with its own flashings and a lead tray around the base.
- Roof vents: tile or ridge vents that let air flow through the roof space to prevent condensation.
- Skylights and roof windows: glazed units set into the roof slope, usually with their own flashing kit.
Flashings are especially important, because they are where most leaks start. See our roof flashing guide for a closer look.
Quick Glossary of Roof Parts
| Part | What it does |
|---|---|
| Rafter | Sloping timber that carries the roof covering |
| Truss | Factory-made timber frame that replaces cut rafters |
| Purlin | Horizontal support for the middle of the rafters |
| Wall plate | Timber on the wall that the roof sits on |
| Batten | Timber strip that tiles or slates hook onto |
| Underlay | Membrane under the tiles that sheds any water |
| Ridge | Top line where two slopes meet |
| Hip | Sloping outside corner where two slopes meet |
| Valley | Sloping inside corner that channels water |
| Verge | Sloping edge at a gable end |
| Eaves | Lower edge of the roof that overhangs the wall |
| Fascia | Board at the eaves that holds the gutters |
| Soffit | Underside of the eaves overhang |
| Flashing | Metal strip sealing joints with walls and chimneys |
Why Knowing the Parts of a Roof Helps
- Comparing quotes. You can see whether each roofer has included battens, underlay, ridge tiles and flashing, rather than just the tiles.
- Spotting problems. When you can describe the damage as a failed valley or a cracked ridge, a roofer can usually diagnose the issue faster.
- Talking to insurers. Claims are clearer when you can name the part that was damaged.
- Planning work. It helps you understand which parts need to be replaced together and which can be repaired separately.
Frequently Asked Questions
What are the main parts of a roof?
The main parts are the structure (rafters or trusses, joists and wall plates), the covering (tiles, battens and underlay), the edges and joints (ridge, hips, valleys, verge and eaves) and the drainage (gutters and downpipes).
What is the difference between a rafter and a truss?
Rafters are individual timbers cut and fitted on site. A truss is a factory-made triangular frame that includes the rafters, joists and internal bracing in one unit.
What is the ridge of a roof?
The ridge is the horizontal line at the very top of the roof where two slopes meet. It is covered with ridge tiles to keep water out.
What is the difference between fascia and soffit?
The fascia is the board at the ends of the rafters that holds the gutters. The soffit is the board underneath the overhang that closes the gap between the fascia and the wall.
What is the roof structure called?
The timber frame that supports the roof covering is called the roof structure. It is made up of rafters or trusses, joists, wall plates and sometimes purlins and collar ties.
Final Thoughts
You do not need to memorise every roofing term, but knowing the main parts of a roof makes quotes, reports and conversations with roofers much easier to follow. Keep this page as a quick reference, and if a quote uses a word you do not understand, ask the roofer to explain it before you agree to the work.
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