A hinged roof is a roof structure whose sloping halves are hinged at the ridge: the whole roof folds open like a book. The Dutch terms are klapkap and scharnierkap. The roof arrives or is lifted flat and is then opened out on site in one movement to the required pitch.
It is essentially a special form of rafter roof, usually built as a gable roof from self-supporting sandwich panels or prefabricated roof elements. It is common on shell-only and catalogue houses.
How it works
- The two roof slopes are made in the factory and coupled at the ridge with a hinged connection
- The package is delivered flat and lifted onto the wall plates or the upper floor
- The crane opens the slopes out to the correct pitch
- The feet are fixed down and the ridge is closed; roof covering and finishes follow
Advantages
- Fast erection — the roof is in place in a single operation, which sharply limits crane and labour hours on site
- Self-supporting — the panels span from wall plate to ridge, so purlins and most decking are no longer needed
- Consistent quality — the work is done in the factory, dry and under controlled conditions
- High insulation value at modest thickness — with sandwich panels the insulation is within the element itself
- Short lead times and freedom in roof shape, because the element is made to measure
Points to watch
- Lift plan and weather — a complete roof slope is a large element that catches the wind; lifting calls for a crane with ample capacity and calm conditions
- Accuracy of the structure below — the wall plates and the top of the upper floor have to be exactly to size and level; a prefabricated element leaves no room to correct on site
- Ridge and eaves detailing — the airtight layer and the vapour control layer must run through at the ridge, the eaves and along the gables, or cold bridges and condensation problems follow
- Plan penetrations in advance — rooflights, chimneys and ventilation penetrations are difficult to add to a finished panel; specify them up front
- Temporary covering — agree how the roof stays watertight between the lift and the final covering
Related terms
- Roof structure
- Purlin roof
- Sandwich panel
- Roof decking
- Roof truss
- Ridge purlin
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