# Penetrations

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**Exterior walls run from bottom to level**: The walls are automatically trimmed with the roof surfaces as soon as they contact a roof surface. Here you can specify up to which level the exterior walls should run. Anything that protrudes above the bottom edge of the level set here will be cut off.

**Interior walls run from bottom to level**: Interior walls are also automatically trimmed with the roof skin. A separate setting can be made for interior walls, since they often need to be trimmed differently than exterior walls.

**Dormer walls run from top to level**: Dormer walls are also automatically trimmed with the roof skin. In contrast to exterior and interior walls, they are cut from above onto the roof surface.

**Normal ceilings run to level**: For ceilings you can set a ceiling type 'intermediate ceiling' or 'boundary ceiling'. This specifies up to which level of the roof surface the intermediate ceilings should run. See also the section 'Trimming of ceiling and roof levels'.

**Boundary ceilings run to level**: For ceilings you can set a ceiling type 'intermediate ceiling' or 'boundary ceiling'. This specifies up to which level of the roof surface the boundary ceilings should run. See also the section 'Trimming of ceiling and roof levels'.

**Kink level for surface areas**: Here the level is defined from which the separation of surface areas (eaves area -- developed area) should continue at a right angle. See also chapter 'Eaves areas'.

### Interruption of levels by walls

With this setting you can control the penetration of roof levels with wall levels in more detail:

**Roof levels**: In this field you specify the roof level for which you want to make a more detailed setting.

**Wall type**: The setting applies to a specific wall type that you select here. This allows you to control whether the setting should apply to all exterior walls, only to the eave walls, or possibly only to the verge walls. The same options exist for interior walls.

**Level, offset**: Using two level numbers you can define the wall area within which the roof levels should be cut out. With the offset, this area can also be shifted so that a roof level ends inside a wall level.
