What Is a Cut Roof? A Carpenter Explains

If you are planning an extension, a loft conversion or a new build with anything other than a simple roof shape, you will probably hear the phrase "cut roof". It is the traditional way of building a roof, and it is still the right answer for a lot of projects, even though factory-made trusses dominate ordinary new builds.

Trussed roof vs cut roof

A trussed roof arrives from a factory as a set of pre-engineered triangular frames. They are craned or carried into place, fixed at 600mm centres, and braced. Fast, cheap and perfectly adequate for straightforward roof shapes. A cut roof is different: every rafter, joist, purlin and ridge board is measured, cut and fixed on site by a carpenter. Nothing arrives pre-made.

When you actually need a cut roof

Trusses only work when the roof shape is simple and the internal span is clear. The moment a design gets interesting, a cut roof takes over. Typical situations include:

• Loft conversions, where the roof space has to stay open and usable
• Hips, valleys, dormers and changes of pitch
• Older properties where nothing is square and every measurement is unique
• Vaulted ceilings and feature roofs that are meant to be seen
• Extensions that have to tie into an existing roof with a different pitch

What goes into one

The main components are the ridge board at the top, common rafters running down to the wall plates, ceiling joists tying the feet of the rafters together, and purlins or steels supporting the rafters mid-span on longer runs. Add hips, valleys, jack rafters and birdsmouth cuts over the wall plate, and you can see why it is skilled work. Every angle is calculated from the pitch, and every cut has to land right because timber is unforgiving of guessing.

Why it costs more than trusses

You are paying for time and skill on site instead of a factory. Materials are broadly similar, but labour is days rather than hours. The payoff is a roof that fits your building exactly, leaves the space open where you need it, and handles shapes a truss plant simply cannot make.

Thinking about a roof project?

Cut roofs sit squarely in our first fix carpentry work across Hampshire. If you have drawings, or even just an idea and a tape measure, get in touch for a free quote and we will tell you honestly whether you need a cut roof or whether trusses will do the job for less.