A hip roof (or hipped roof) is a roof in which all four sides slope downward to the eaves, meeting at a central ridge. There are no vertical gable ends - instead, the ends of the building are closed by sloping triangular or trapezoidal roof planes, formed by diagonal hip rafters running from the corners of the wall plate to the ends of the ridge. This gives the building a lower, more horizontal profile than a gabled roof of the same pitch and span.

What is the difference between a hip roof and a gable roof?

A gable roof has two sloping roof planes meeting at a central ridge, with vertical triangular gable end walls at each end. A hip roof has four sloping planes (two main slopes and two hip ends) with no vertical gable walls. The hip roof is more wind-resistant - its lower profile and lack of large vertical surfaces present less area to wind pressure, making it common in exposed coastal and upland areas. Gable roofs are simpler and cheaper to build, easier to extend, and allow a full loft space with vertical gable end walls for natural light.

What is a hip rafter?

A hip rafter is the diagonal rafter that runs from the corner of the wall plate up to the end of the ridge, forming the sloping corner arris (the hip line) of a hipped roof. It receives the top ends of the jack rafters on either side. Hip rafters must be deeper than the common rafters they receive - typically the common rafter depth plus 50mm - because they carry loads from two slopes and run at a longer diagonal angle. Hip rafter sizing requires separate calculation from common rafters and is covered in TRADA Span Tables or by structural engineering.

What is a hip-to-gable loft conversion?

A hip-to-gable loft conversion involves removing the sloping hip end of the roof and replacing it with a vertical gable wall, extending the ridge to the new gable end. This creates significantly more usable floor area in the loft than a dormer-only conversion on a hipped roof. The hip rafters and jack rafters are removed, a new gable wall is built (typically timber frame clad in masonry to match the house), and a new ridge board extended. Hip-to-gable conversions are popular on 1930s and post-war hipped roof semi-detached houses and are often Permitted Development.

Roofing noun

Hip Roof

/ hɪp ruːf /

Also known as: hipped roof, hip end, hip-and-valley roof

Definition

A hip roof is a roof form in which all four sides slope downward to the eaves wall plate, with no vertical gable end walls. Diagonal hip rafters run from each corner of the wall plate to the ends of the central ridge, and the sloping triangular end sections (the hips) replace the gable walls of a conventional pitched roof. Hip roofs have a lower, more horizontal profile than gabled roofs and are more resistant to wind - they are common in exposed locations and in certain regional building traditions (especially 1930s suburban housebuilding).

In practice

Building a hipped roof is significantly more complex than a simple gable roof. The hip rafters run at 45 degrees to the wall plate (in plan) for a square building, but at other angles for rectangular plans. Jack rafters fill in between the hip rafter and the wall plate on each hip. All jack rafters are different lengths, requiring individual cuts. Hip rafter sizing must account for the combined loading from both adjacent roof slopes - hip rafters are typically 50mm deeper than the common rafters they receive.

For modern trussed rafter hip roofs, a girder truss (two or three standard trusses bolted together) is positioned at the hip setback point, and hip-set trusses of diminishing height step down to the hip corner. This avoids the traditional cut-roof geometry but requires a more complex design from the truss manufacturer. On extensions, matching the pitch and hip detail of an existing hipped roof is a planning requirement in many areas - planners often insist that extensions read as subordinate, with matching roof forms.

Building Regulations

Relevant PartPart A - Structure

Hip rafter sizingMust be calculated separately from common rafters

Hip-to-gable conversionUsually Permitted Development - check local conditions

Hip roofs are covered by Approved Document A - Structure. Hip rafter sizing requires engineering input beyond the standard TRADA common rafter span tables, as hip rafters carry loads from two slopes at a diagonal angle. Hip-to-gable loft conversions are generally Permitted Development in England (subject to volume limits and location - conservation areas, listed buildings, and designated areas are excluded) but always require Building Regulations approval for the structural and thermal elements of the new gable and roof structure.

Full Building Regulations guidance

Hip Roof

Just so you know...