Hipped Trussed Rafter Roofs
The hipped roof is one of the most common and attractive of the trussed rafter ‘roofscapes’. The are a number of members of the hip roof family providing a variety of designs to choose from.
- The standard hip
- The Dutch or Barn Hip
- The Louvred Hip
- Rectangular Pyramid
- Hip Corner – Equal Ridge Height
- Hip Corner – Equal Roof Pitch
Hip Roof Systems
- A hip system is the collective name for a group of trussed rafters that form the hip
- A hip end is a complex three dimensional framework, which, for simplicity, is treated as a two-dimensional problem. In design, the hip board is sized to satisfy an ultimate load criteria for safety reasons. In practice it carries negligible load
- Although hips above 12m span are common and spans of 20m have been achieved, special details may be required depending on roof pitch and the location of internal load bearing walls. Consequently it may pay to contact you fabricator at the planning stage, providing as much information as you can.
- Generally the minimum preferred pitch is 22.5 degrees, which allows adequate depth for the girders supporting the hip.
- Where the pitch on the end is different to that on the sides, the specifier has two options.: either the steeper pitch must be cantilevered or the soffit width varied to maintain the eaves line.
- All normal roof finishes can be used and modifications such as stub ends and small cantilevers, can be incorporated.
- Through discussion with the roof designer, hip girders can be positioned to avoid chimneys or to prevent large reactions (loadings) occurring over windows.
- In some instances, pre-made components can be provided to simplify and speed up the construction of the infill areas.
Standard Hip End Construction
The design of the standard hip end roof has evolved to reduce traditional infill to a minimum – thereby keeping site material and labour costs down.
The main structural components consist of a multi-ply hip girder which supports the mono pitch trusses and hip rafters forming the hip.
Single hip girders are then used as infill up to the first full truss at the end of the ridge. Generally the same truss spacing is maintained throughout for reasons of economy.
The mono-pitch trusses and the single hip girder trusses may be supplied with extended rafters for site fixing to the hip rafter.
Mono and infill shoes are used for supporting mono pitch trusses on the hip girder truss.