Simple gable roofs are quickly modeled – but what if the building has dormers, roof offsets, or complex roof shapes? Without the right techniques, extruding leads to crooked or faulty 3D models.

Typical challenges:

The solution: Three critical success factors determine success or failure with complex roofs:

In this video from our Video Training Center, you'll see the techniques in action:

With complex roofs, the quality of map material is even more important than with simple buildings. The better the quality, the more precise the 3D model becomes.

Orthophotos are always taken vertically from above and contain no perspective distortions. This is ideal for precise drawing.

Identifying problematic satellite images:

Symmetric drawing is the key to a precise and professional 3D model. The Solar Expert's snap functions help you with this.

After the floor plan, draw the inner roof edges – i.e., ridges, valleys, hips, and other inner lines.

For a simple hip roof with multiple corners:

Why is symmetry so important? When floor plan and inner roof edges are drawn symmetrically and precisely, this geometry automatically transfers to the 3D model. An asymmetric floor plan inevitably leads to an asymmetric 3D model.

This is the key concept for modeling complex roofs. Without split roof edges, dormers and roof offsets won't be displayed correctly.

A split roof edge is a line in the floor plan where two different heights exist. This typically happens:

Visualization using dormer example:

Imagine a dormer sitting in a roof slope. The dormer gutter runs parallel to the sloping main roof surface. On the line where the dormer gutter meets the main roof surface, we have two heights:

This line must be marked as a "split roof edge" so that the Solar Expert knows that two different heights exist here.

A roof offset occurs when the roof runs at two different heights – for example, with an addition or a higher building part.

Starting situation: You have drawn floor plan and inner roof edges, but when extruding an error occurs – the roof becomes crooked.

Solution:

Why does this work? Without marking as split roof edge, the Solar Expert tries to create a continuous roof surface. With the marking, the system knows that a height jump exists here and models two separate levels accordingly.

Dormers are more demanding because they often have three or more split roof edges. But with the right systematic approach, they are manageable.

Preparation: Floor plan and ridge are already drawn and the main roof is extruded.

Result: The dormer is now correctly modeled. You can see the split roof edges in the 3D view – where the dormer gutter runs on one hand, and the sloping main roof surface on the other.

If multiple dormers exist, repeat the process for each dormer individually:

Important: For each new dormer, you must check again which edges need to be marked as split roof edges.

Cause: Split roof edges were not marked.

Symptom: The roof tilts to the side or the geometry looks distorted.

Solution:

Cause: Not all split roof edges were marked, or the wrong edge was extruded as peak.

Solution:

Cause: Floor plan or inner roof edges were not drawn symmetrically.

Solution:

Cause: Complex geometry, many edges, uncertainty.

Solution: Use this checklist:

When in doubt: Mark the edge as split and check the result when extruding. If the model looks wrong, you can remove the marking again.

Core message: With these three success factors, you can professionally model even very complex roofs. It may seem elaborate at first, but with some practice, the process becomes routine.

After you can model complex roofs, we recommend:

Practice makes perfect: Complex roofs require experience. With each building you'll become faster and more confident. Don't shy away from taking on challenging projects – you now have all the tools you need!

The complete Video Training Center – Module 3 also shows complex examples visually and with practical demonstration.