Roof Components - Sills / Intermediate Purlins

The 'Purlins / Middle purlins' function allows entry of different purlin types. The function is intended for entering sills, foot purlins, and middle purlins. The selection of the purlin type is made in the 'Designation' field. Depending on the chosen purlin type, some labels in the dialog box change accordingly.

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 material of the purlin. Using the button at the end of the field, you can branch into the database and select a material.

Designation: By selecting the designation, a specific purlin type is chosen simultaneously. Depending on this purlin type, purlins can be positioned differently. Accordingly, some fields in the dialog box change their meaning and labels. For example, chamfered purlins are positioned not by a bearing timber but by the chamfer width and an air gap. For skewed purlins, the rotation angle can be entered.

Width: Purlin width.

Height: Height of the purlin.

Position: Layer to whose top edge the reference timber relates. Typically this is layer 0, in which the rafters also lie. If you want to enter coupling purlins, you will likely have a layer above layer 0 that is as thick as the coupling purlins are high. Then select that layer here and enter a reference timber of 0.000.

Purlin edge to be positioned: Any of the 4 edges of a purlin can be positioned. The selected edge is then taken into account for the values 'Distance in plan' and 'Top edge / bottom edge purlin height'. The reference timber, however, always refers to the front, top edge, regardless of which edge was selected here.

Rotate cross-section: The 'Rotate cross-section' field is active only when you have selected a twisted purlin in the 'Designation' field. With the 'Roof pitch' option, the purlin always receives the appropriate rotation for the roof pitch of the roof plane on which the purlin is entered (e.g., for coupling purlins). With 'Value' any rotation angle may be entered.

Bearing timber type horizontal / vertical or Chamfer width: This field changes its meaning depending on the selected purlin type. For chamfered purlins the chamfer width can be entered here. For all other purlin types the bearing timber type is set here.

Bearing timber referenced to level or Distance from top edge of level: This field changes its meaning depending on the selected purlin type. For chamfered purlins, the distance to the top edge of the selected layer can be entered here. For all other purlin types, the reference timber matching the reference timber type is entered here. This field is linked to the next two fields. You may always enter only two of the three fields; the third is calculated. To enter the disabled field, delete the contents of one of the other two fields.

Top edge / bottom edge purlin height: Depending on the selected purlin edge for positioning, you can enter here the height of the top edge or the bottom edge. This field is linked to the next and previous field. You may always enter only two of the three fields; the third is calculated. To enter the disabled field, delete the contents of one of the other two fields.

Distance in plan: Depending on the selected purlin edge for positioning, you can enter here the plan distance from the reference edge specified in the next field to the front or rear purlin edge. This field is linked to the two previous fields. You may always enter only two of the three fields; the third is calculated. To enter the disabled field, delete the contents of one of the other two fields.

Reference for distance in plan: When entering the distance in plan, you can choose the reference line for the distance here. The 'Wall outer edge' and the 'Reference axis' can only be used if walls have actually been entered in the plan. With the 'Choice' option you can later select any line during placement.

Purlin direction: With the 'Purlin direction' option you specify at which end of the purlin the purlin start and at which end the purlin end is located. For this purpose, the roof surface is viewed from the eaves. This information is important when writing the member numbers at the member start on the rafter-purlin plan and when you want to influence the position of the number.

In addition, this setting affects the transfer of the purlins to the machine: Two opposite purlins on a gable roof are both entered with the start on the left (Left -> Right). The rafters lie at different spacings on one roof surface and were adopted to the other roof surface in this way. Marks are generated on the purlins from the rafters. As a result, both purlins are different after sorting and are transferred separately to the machine. If one purlin has the start on the left and the opposite purlin has the start on the right, the marks on the purlins have the same distance to the respective member start. Therefore both purlins are identical and receive the same number during sorting.

Rafter to purlin connection: There are six settings in this field:

None: No connection is made; both members penetrate each other.

always cut: When penetrating with this purlin, the rafters always receive a cut, even if the rear edge of the purlin penetrates into the rafters.

always cut (consider plates in front of purlin): Rafters also always receive a notch when intersecting with this purlin, even if the rear edge of the purlin penetrates into the rafters. In addition, the program searches for panels in front of the purlin. If panels in front of the purlin are found, the notch is increased by the panel thickness. The panels must be perpendicular to the global XoY plane and must be parallel to the front purlin face. The panel must touch the front purlin face and the top of the panel may end flush with or up to 20 mm below the top of the purlin. The panel may have been created in DICAM or in the wall. Since version V19.01, panels on the rear side of the purlin are also taken into account and the notch is generated correspondingly deeper.

possibly mortise: Rafters receive a notch when intersecting with this purlin as long as the rear edge of the purlin does not penetrate into the rafters. As soon as the rear edge of the purlin penetrates into the rafters, however, a cutout is created in the rafter. In this process, the threshold 'Minimum cutout depth' is also taken into account. As long as the cutout depth is less than the threshold set here, the cutout will still not be created. A notch will continue to appear.

possibly mortise (consider plates in front of purlin): Rafters receive a notch when intersecting with this purlin as long as the rear edge of the purlin does not penetrate into the rafters. As soon as the rear edge of the purlin penetrates into the rafters, however, a cutout is created in the rafter. In this process, the threshold 'Minimum cutout depth' is also taken into account. As long as the cutout depth is less than the threshold set here, the cutout will still not be created. A notch will continue to appear. In addition, the program searches for panels in front of and behind the purlin. If panels in front of or behind the purlin are found, the notch is increased by the panel thickness. The panels must be perpendicular to the global XoY plane and must be parallel to the front purlin face. The panel must touch the front or rear purlin face and the top of the panel may end flush with or up to 20 mm below the top of the purlin. The panel may have been created in DICAM or in the wall. Since version V19.01, panels on the rear side of the purlin are also taken into account and the notch is generated correspondingly deeper.

Cut in purlin: With this option no cut or mortise is created in the rafter. Instead, the purlin receives a mortise (free cut).

Connect purlin end to ridge / valley rafter: As soon as a purlin touches a ridge or valley rafter (or valley beam) with the member end, the connection specified here is generated. Most options should be self-explanatory and their parameters can be set using the button at the right end of the field.

The options 'always notches', 'always notches (consider panels in front of purlin)', 'possible cutout' and 'possible cutout (consider panels in front of purlin)' apply when the purlin does not fully meet the side face of the ridge or valley rafter (as required for the other options), but only partially penetrates it. The connection is the same as described under 'Rafter to purlin connection'. The 'Cutout in purlin' option also creates a free cutout in the purlin.

Rafter nail hole: A rafter nail hole can be created in two ways. It can simply be information attached to the cut or an independent hole can be created. Both options have different characteristics:

From cut: The information for the rafter nail hole is attached as information to the notch and is passed to the machine in that way, and the machine then treats the rafter nail hole as such. This type of rafter nail hole is not displayed in the structure. The diameter of this rafter nail hole is under 1-7-8 Limits, machining set. This rafter nail hole is created on cuts and free cuts.

Rafter nail hole: Below this group you can choose a custom, detailed setting. If one of these options is selected, the rafter nail borehole is no longer generated as information at the notch, but instead a separate borehole is created and represented as such. In addition, the rafter nail can also be generated as a fastener. This rafter nail borehole is generated at notches, free notches (also at ridge and valley rafters), corner notches and cutouts (for very flat rafters).

Purlin to purlin connection: With this connection, purlins that meet beneath a hip or valley rafter can be automatically connected to each other. Two connection types are available, each with several options. If both purlins that meet beneath the hip or valley rafter have been assigned different connections, no connection is made.

Section: For the 'Section' connection there are two options. With 'continuous' each of the two purlins is simply cut vertically. At a valley line the purlin is created so that its rear edge ends exactly at the valley line. At a ridge line the purlin is created so that its front edge ends at the ridge line. With the 'angle bisected' option both purlins are cut along the angle bisector.

End plate: With the 'End plate' connection both purlins are connected with an end plate. The end plate can be created according to different criteria. The options of this connection allow you to specify which of the two purlins should receive the end plate on top.

Rafter roof construction: In this drop-down list you can select settings for rafter roof construction. The settings can be configured and saved using the browser button at the right edge of the list. See also corbel constructions and bearing block constructions.

Because this construction is attached to the purlin, every rafter that touches this purlin automatically receives a corbel or bearing block construction. If you delete the purlin, these construction timbers are also deleted. If you move the purlin, the corbels and bearing blocks also move.

Shortening at the verge: As soon as a purlin ends at the verge during input, it is shortened by the value entered here. Negative values result in an extension of the purlins.

End machining at verge: As soon as a purlin ends at a verge according to the input, the machining set here is attached to that purlin end. The parameters with which the chosen machining is executed can be viewed and modified using the button at the right end of the field.

Shortening of the remaining purlin ends: As soon as a purlin ends at another roof line than an eave when entered, it is shortened by the value entered here. With negative values you obtain an extension of the purlins.

After setting all values and options you can enter the purlins using the following controls:

All roof surfaces: The selected purlin will be generated on all roof planes.

Continuous: The purlin will be generated on the roof plane(s) that were selected graphically.

Length-limited: By two points the length and position of the purlins can be defined. The first entered point simultaneously determines the roof plane on which the purlin shall be created.