Add a roof: gable, hip, shed or flat

Roofs are drawn from your walls, so they always fit the building. You choose the shape and pitch; the ridge height, hips, valleys and roof area are worked out exactly.

Before you start

• Closed rooms or walls on the floor the roof sits on, usually your top floor. The roof follows the outside face of the outer walls, including L- and U-shaped plans.
• Edit access to the design.

Add a roof

1. Open Roof & site in the left rail (the house icon). On a phone, tap More and choose Roof & site.
2. Make sure the floor the roof sits on is showing (use the floor switcher at the top of the canvas).
3. Under Add a roof, choose Gable, Hip, Shed or Flat. The roof appears on the plan as a dashed outline with its ridge and hip lines, and in 3D.
4. Set the Pitch. Type degrees (30) or rise over run (6/12, 4:12), or pick a common pitch. The field shows both, for example "6/12 (26.6°)".
5. Set the Overhang (eaves), the distance the roof extends past the walls, for example 12" or 300 mm.
6. For gable and shed roofs, set the Ridge direction. Turn 90° swaps which walls get the gable ends; Along long side puts the ridge along the building's length. For a shed roof, Flip slope swaps the high and low sides.
7. Choose the Roofing: asphalt shingles, standing-seam metal or clay tiles.

How the roof is calculated

• The roof sits on top of its floor: the floor's elevation plus its floor-to-floor height. Use Raise or lower to adjust it.
• The roof planes pass through the top of the walls at the outside wall face. A 30° roof over an 8 m (26 ft 3 in) wide building rises 4 m × tan 30° = 2.31 m above the walls, whatever the overhang.
• Hip roofs slope on every side. Where planes meet you get hips (outside corners) and valleys (inside corners of L- and U-shaped plans). On a rectangle the ridge is the length minus the width.
• Gable roofs have two slopes meeting at a ridge through the middle of the building in the ridge direction. The triangular gable ends are filled in with wall in 3D.
• Roof area in the panel, in the room schedule CSV and in the budget estimate is the true sloped surface (plan area including eaves divided by the cosine of the pitch).

When walls change

The roof keeps its outline until you refit it, so editing walls never moves a roof by surprise. When the walls no longer match, the panel says so: choose Refit (or Refit to walls) to regenerate the outline.

Seeing inside

• In 3D, use the Roof button in the toolbar to hide or show roofs. Roofs are always hidden in Cutaway so you can look into the rooms.
• On the plan, switch off Show roofs on the plan in the panel if the roof outline gets in the way while you furnish.

Printing and exports

• PDF and image exports include the roof plan on the floor the roof sits on.
• DXF exports put roofs on the ROOF layer: the eaves outline (dashed), the wall-line footprint, ridge, hip and valley lines, and a pitch label.
• The room schedule CSV lists each roof with its pitch, plan and sloped area, ridge height and the lengths of ridges, hips, valleys and eaves.

Current limits

• Each roof uses one pitch on all of its planes. For a mix (for example a steep main roof and a shallow porch), add a second roof over the porch outline.
• A gable roof on an L- or U-shaped plan is one pair of planes over the whole outline, not separate cross-gables. Use a hip roof for exact valleys at inside corners.
• Curved walls are followed along their arcs, within about 5 mm (1/4 in).
• Dormers, skylights and chimneys aren't modelled yet.
• Roof structure (rafters, trusses) isn't calculated; quantities are surface areas and lengths only.

Common problems

• "Draw closed walls on this floor first." The roof needs a closed outline. Close any gaps in the outer walls, or switch to the floor that has walls.
• The roof is on the wrong floor. Roofs belong to the floor they sit on. Delete it and add it again with the right floor showing.
• "Roof pitch must be between 1° and 75°." Use a flat roof for anything shallower than 1°.