Rechner für Schleppgauben-Konstruktion & Kehlwange

The side-section solver intersects the dormer roof plane with the main roof plane. Setback is measured horizontally from the main-roof eave datum; wall height starts at the shared plate datum.

Worked example: with the default 8-in-12 main roof, 3-in-12 dormer roof, 1200 mm setback and 1800 mm front wall, the planes meet 3600 mm from the eave datum at 2400 mm above the plate.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Main roof rise

8

Main roof run

12

Dormer roof rise

3

Dormer roof run

12

Dormer front setback from eave

1200 mm

Dormer front wall height above plate

1800 mm

Dormer outside width

3000 mm

Primary result: Main-roof tie-in run: 3600.0 mm.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

This is side-section layout geometry for roofs sharing one plate datum. It does not design headers, doubled rafters, loads, flashing, overhangs or structural connections. Confirm cheek-valley plan geometry and framing sizes from the project drawings.