- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 18 Oct 2018
Eaves are the part of a roof that projects out horizontally beyond the side of the structure it covers. They can have practical functions, such as to provide shade and protection from rain, as well as aesthetic functions, creating a definite distinction between walls and roof.
Typically, the eave’s width is related to the roof pitch. The steeper the pitch is, the narrower the eaves.
 Types of eaves
There are four basic types of eaves:
- Exposed: The finished underside of the roof and supporting rafters are visible from underneath.
- Soffited: Includes a soffit – the panelling which forms the underside of the eaves, connecting the bottom tip of the eave with the side of the building at a 90-degree angle.
- Boxed-in: Encases the roof rafters but meets the side of the building at the same angle as the roof pitch.
- Abbreviated: Cut off almost perpendicular with the side of the building.
Exposed, soffited and boxed-in eaves generally include air vents to ventilate the roof space or roof structure, preventing the accumulation of moisture and so reducing the likelihood of condensation forming. Eaves can also incorporate guttering, which conveys rainwater run off from the roof to a drainage system.
 Purposes of eaves
Eaves can also provide shading to windows, helping to maintain comfortable internal conditions. In the winter, low-level sun is able to penetrate windows to warm and light the interior, whereas in summer, the projecting eaves prevent direct sunlight from entering the building.
They can also be used to help define the architectural style of a building. For example, Dutch Colonial houses featured flared eaves that curved up and away from the roof; the architect Frank Lloyd Wright often used sweeping, elongated eaves in his Prairie house designs; and traditional Asian pagodas are defined by tiers of multiple eaves. A-frame houses include eaves that can reach ground level. A characteristic element of the Italianate style is buildings with decorative, overhanging eaves on a slightly pitched roof.
 Related articles on Designing Buildings Wiki
Featured articles and news
How it can benefit construction.
Free guide to commissioning for site managers published by NHBC and BSRIA.
Resolving quickly to minimise delay and costs.
Tackling domestic abuse.
Disallowed costs vs. defined costs. Which is which?
Coping with the loss of local authority conservation services.
Remedial works could save the NHS £95 million a year.
One of Europe’s largest waterfront transformations.
How BIM was used to produce an information model of a home.
Skyscrapers of the future will be built of wood.
How to increase your chances of winning.