Roof Components - Oblique Rafters

The "skew rafter" function allows placing rafters into a roof surface at any angle relative to the roof's fall direction. The rafter's top surface always remains flush with the top surface of the roof. The following settings are available:

With the selection list at the top of the dialog box you can choose existing settings. Using the disk icon you can save the current setting under the same name or a new name. Via the management icon you can create new settings, also by adopting existing settings, or modify or delete existing settings. See 'Save settings' in the 'General Help' manual.

Identification number: The identification number determines the rafter material. Use the button at the end of the field to open the database and select a material.

Member type / designation: The member type and designation can be entered freely. If the entry is left empty, the member type is automatically selected to match the situation. By assigning a specific member type, these components may not be considered rafters in certain contexts. For example, a component can be ignored when creating formwork if "rafter oriented" is used. Likewise, it can be excluded as a reference component when generating counter-battens. If the rafter has member type 114 / element-field rafter, it does not generate markings on purlins. The component itself receives markings.

Chamfering: Skew rafters can be chamfered on both sides, chamfered only on the top, vertical without chamfering, or skewed (= without chamfering). The chamfers are generated automatically. With the "skewed" option, the skew rafter is automatically skewed so that its top surface remains flush with the surface of the layer.

Width: Width of the skew rafter.

Height: Height of the skew rafter. For the height you can enter a fixed value or have it calculated according to the regular rafters. If you choose the "according to rafters" option, the following fields are enabled. There you can enter a rounding value and the shift height for both sides.

Rafter height: For the "according to rafters" calculation the program needs the rafter height on which the skew rafter height should be based.

Round height to: If you have the skew rafter height calculated from the rafters, you can enter a rounding value here. The calculated height will then be rounded up to the next full value set here. For example, a value of "0.02m" will yield heights in cm of: 10, 12, 14, 16, etc.

Position: Layer in which the rafters are installed. The rafters' top surface lies flush with the top edge of the layer.

Lowering: The skew rafter can be lowered relative to the top edge of the layer by a specified amount.

Positioning: With the positioning you specify which point of the skew rafter should be positioned:

Choice: With the "choice" option, after selecting the point where the rafter should be placed, you can graphically choose among the positioning options (left edge, center, right edge, diagonal). The program starts with one position; use the right mouse button to cycle to the next option and the left mouse button to accept the current position.

Left edge: The left edge of the rafter's top surface, as seen from the eave of the selected roof surface, is positioned.

Center: The center of the rafter's top surface is positioned.

Right edge: The right edge of the rafter's top surface, as seen from the eave of the selected roof surface, is positioned.

Diagonal: With this option the skew rafter can be placed by two diagonal points. The two possible positions (lower left - upper right point and lower right - upper left point) are offered graphically and you select the desired position with the left mouse button. Use the right mouse button to switch to the other position. With this option the direction can only be specified via two points. Therefore the next field is deactivated and the "2 points" option is fixed.

Direction: The "direction" setting influences the input method for the skew rafter. This option affects the subsequent workflow of the function. The following possibilities exist:

Parallel: In the subsequent workflow you select a line. The skew rafter will then be placed parallel to that line within the roof surface.

Perpendicular: In the subsequent workflow you select a line. The skew rafter will then be placed perpendicular to that line within the roof surface.

2 points: In the subsequent workflow you select two points. These points determine the direction of the skew rafter.

Consider as field boundary: With this setting you can specify whether the skew rafter should be considered a field boundary. This affects the subdivision of a field with regular field rafters and the filling of the roof surface using the roof assistant. If a skew rafter is not considered a field boundary, the program will ignore it during subdivision or when using the roof assistant, as if it did not exist. If it is considered, it will bound a field during manual subdivision or subdivision by the roof assistant.

Generate band: As soon as the "create band" option is set to "all", not a single skew rafter is created but, depending on the situation, several skew rafter segments. These segments result from the rafter connecting to every timber it crosses. Therefore the segments (the band) are only created when a connection is set for the member start and the member end. If no connection is set in these fields, the skew rafter segments cannot connect and no segments are created. With the "continuous" input function a continuous skew rafter is first created, then split into segments, and these segments are then connected to the other timbers. With the "length-limited" input function a skew rafter with the entered length is first created, then split into segments, and these are subsequently connected to the other timbers.

Rafter nail hole: A rafter nail hole can be created in two ways. It can simply be an annotation at the notch or it can create a dedicated drill hole. Normally the rafter nail hole is set on the purlin and all rafters, hip rafters, and valley rafters that receive a notch from that purlin also receive this rafter nail hole. In some cases a single component should receive a different rafter nail hole. Then you can give that component its own setting. Both options have different properties:

From purlin: The rafter nail hole is inherited from the purlin that creates the notch in the skew rafter. This may be a rafter nail hole as information at the notch or an independent rafter nail hole, depending on the purlin settings.

Rafter nail hole: Below this group you can choose a custom, detailed setting that applies only to this skew rafter and "overrides" the purlin setting. If one of these options is selected, the rafter nail hole is no longer created merely as information at the notch but becomes an independent hole that is displayed as such. Additionally, the rafter nail can also be generated.

Connection start / end: With these fields you can set a connection for length-limited skew rafters, similar to what you know from wall or ceiling construction. For continuous skew rafters the connection is ignored.

Rafter at eave: For connecting the skew rafter to an eave line you can choose various treatments. You can view and modify the values used to generate each treatment via the button at the right end of the field. These treatments are always generated perpendicular to the side surface of the skew rafter.

Depending on the setting in the "direction" field, you now select a line or two points for the skew rafter direction. The chosen line only determines the direction; the skew rafter can be located further from that line. Therefore you next select a point that determines the rafter's position. If you chose the direction via two points, the skew rafter will also be placed along those two points. Finally, you may enter an offset. The skew rafter will then be additionally shifted by this amount.