Roof plan

A roof plan looks down on a building to explain the shape of its roof and how water is carried away. On pitched roofs it shows the direction and pitch of each slope and the ridge, valley and gable lines; on flat roofs it shows outlets, falls and parapets.

What a roof plan contains

• Fall arrows and pitch or slope values
• Ridges, valleys, eaves and gables
• Gutters, rainwater outlets and downpipes
• Chimneys, vents, rooflights and roof access hatches
• The roof covering, and where relevant solar panels or plant layout

Why it gets its own drawing

The roof takes more weather than any other part of a building. A fall in the wrong direction, too few outlets or a valley trapped behind a chimney can start leaks that last for years. The roof plan lets you see these problems before they are built, and read with the sections it fixes the roof’s height and form.

In aerial renders and drone-style images the roof becomes the building’s fifth facade. The more carefully the roof plan is resolved, with tidy plant layout or a well-planned roof terrace, the more composed those images look.