# Roof Components - Sills / Middle Purlins

## The purlin settings

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With the 'Threshold / Intermediate purlins' function you can enter different purlin types. The function is intended for entering thresholds, base purlins and intermediate purlins. The choice of purlin type is made in the 'Designation' field. Depending on the selected purlin type, the labels in the dialog box change in places.

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

**ID number:** The ID number determines the material of the purlin. Using the switch at the end of the field you can branch into the database and select a material.

**Designation:** The designation simultaneously selects a specific purlin type. Depending on this purlin type, the purlins can be positioned differently. For this purpose, the fields in the dialog box sometimes change their meaning and labels. For example, beveled purlins are positioned not by a ledger board but by the bevel width and an air gap. For skewed purlins the rotation angle can be entered.

**Width:** Width of the purlin.

**Height:** Height of the purlin.

**Level:** Level whose top edge the ledger board refers to. As a rule this is level 0, in which the rafters also lie. If you want to enter coupling purlins, you probably have above level 0 a level that is as thick as the coupling purlins are high. Then select this level here and enter a ledger board of 0.000.

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**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 'Offset in plan' and 'Height top edge/bottom edge of purlin'. The ledger board, however, always refers to the front, top edge, regardless of which edge was selected here.

**Rotate cross-section:** The 'Rotate cross-section' field is only active when a skewed purlin has been selected in the 'Designation' field. With the 'Roof pitch' option the purlin always receives the appropriate rotation for the roof pitch of the roof surface on which the purlin is entered (e.g. for coupling purlins). With 'Value' any rotation angle can also be entered.

**Ledger board type horizontal / vertical** or **Bevel width:** This field changes its meaning depending on the selected purlin type. For beveled purlins the bevel width can be entered here. For all other purlin types the ledger board type is set here.

**Ledger board relative to level** or **Distance from top edge of level:** This field changes its meaning depending on the selected purlin type. For beveled purlins the distance to the top edge of the selected level can be entered here. For all other purlin types the ledger board corresponding to the ledger board type is entered here. This field is linked to the next two. You can always enter only two of the three fields; the third is calculated. To enter the disabled field, delete the content of one of the other two fields.

**Height top edge/bottom edge of purlin:** 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 can always enter only two of the three fields; the third is calculated. To enter the disabled field, delete the content of one of the other two fields.

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

**Reference for offset in plan:** When entering the offset in plan you can choose the reference line for the offset here. The 'Wall outer edge' and the 'Reference axis' can only be used if walls have in fact been entered in the plan. With the 'Select' option you can later choose 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 the purlin end is located. For this, the roof surface is considered from the eave. 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.

Additionally, this setting affects the transfer of the purlins to the machine: Two opposing purlins on a gable roof are both entered with the start on the left (Left -> Right). The rafters lie at different distances on one roof surface and have thus been transferred to the other roof surface. Marks are generated from the rafters on the purlins. As a result, both purlins are different after sorting and are transferred to the machine separately. If one purlin has the start on the left and the opposing purlin 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.

## The connections of the purlins

### Rafter to purlin connection

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

> * **None:** No connection is created; both members penetrate each other.
>
> **always rebates:** When penetrating this purlin, the rafters always receive a rebate, even when the rear edge of the purlin intrudes into the rafters.
>
> **always rebates (consider plates in front of purlin):** When penetrating this purlin, the rafters also always receive a rebate, even when the rear edge of the purlin intrudes into the rafters. In addition, the program searches for plates in front of the purlin. If plates in front of the purlin are found, the rebate is enlarged by the plate thickness. The plates must stand perpendicular to the global XoY plane and must be parallel to the front purlin face. The plate must touch the front purlin face and the top edge of the plate can end flush with or a maximum of 20 mm below the top edge of the purlin. The plate can have been created in DICAM or as a wall.\
> Since version V19.01 plates on the rear side of the purlin are also taken into account and the rebate is produced correspondingly deeper.
>
> **possibly cut-out:** When penetrating this purlin, the rafters receive a rebate as long as the rear edge of the purlin does not intrude into the rafters. However, as soon as the rear edge of the purlin intrudes into the rafters, a cut-out in the rafter is generated. The limit value 'Minimum depth of cut-out' is also taken into account here. As long as the cut depth is less than the limit value entered here, the cut is still not generated. A rebate continues to appear.
>
> **possibly cut-out (consider plates in front of purlin):** When penetrating this purlin, the rafters receive a rebate as long as the rear edge of the purlin does not intrude into the rafters. However, as soon as the rear edge of the purlin intrudes into the rafters, a cut-out in the rafter is generated. The limit value 'Minimum depth of cut-out' is also taken into account here. As long as the cut depth is less than the limit value entered here, the cut is still not generated. A rebate continues to appear.\
> In addition, the program searches for plates in front of and behind the purlin. If plates are found in front of or behind the purlin, the rebate is enlarged by the plate thickness. The plates must stand perpendicular to the global XoY plane and must be parallel to the front purlin face. The plate must touch the front or rear purlin face and the top edge of the plate can end flush with or a maximum of 20 mm below the top edge of the purlin. The plate can have been created in DICAM or as a wall.\
> Since version V19.01 plates on the rear side of the purlin are also taken into account and the rebate is produced correspondingly deeper.
>
> **Cut into purlin:** With this option no rebate and no cut-out is created in the rafter. Instead, the purlin receives a cut-out (free notch).

**Connection purlin end to ridge/valley rafters**: As soon as a purlin with the member end touches a ridge or valley rafter (or valley plank), the connection set here is generated. Most options should be self-explanatory and their parameters can be set via the switch at the right end of the field.

The options 'always rebates', 'always rebates (consider plates in front of purlin)', 'possibly cut-out' and 'possibly cut-out (consider plates in front of purlin)' apply when the purlin does not fully meet the side face of the ridge or valley rafter (as necessary for the other options), but only partially penetrates it. The connection is the same as described in 'Rafter to purlin connection'. The 'Cut into purlin' option also creates a free notch in the purlin here.

### Rafter nail hole

**Rafter nail hole**: A rafter nail hole can be generated in two ways. This can simply be information attached to the rebate or an actual hole can be generated. Both options have different properties:

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> **From rebate**: The information for the rafter nail hole is attached as information to the rebate and is also transferred to the machine as such, and then the machine treats the rafter nail hole accordingly. This type of rafter nail hole is not displayed in the structure. The diameter of this rafter nail hole is set under 1-7-8 *Limits, machining* set.\
> This rafter nail hole is generated at rebates and free rebates.
>
> **Rafter nail hole**: Below this group you can choose your own detailed setting. If one of these options is selected, the rafter nail hole is no longer created as information attached to the rebate, but a separate hole is created which is displayed as such. In addition, the rafter nail can also be generated as a fastener.\
> This rafter nail hole is generated at rebates, free rebates (also on ridge and valley rafters), at corner rebates and notches (for very flat rafters).
>
> Purlin to purlin connection

### Purlin to purlin connection

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**Purlin to purlin connection**: With this connection purlins that meet under a ridge or valley rafter can be automatically connected to each other. Two connections are available, each with several options. If both purlins that meet under the ridge or valley rafter have different connections, no connection is created.

> **Section**: For the 'Section' connection there are two options. With 'through' each of the two purlins is simply cut off vertically. At a valley line the purlin is produced so that the rear edge of the purlin ends exactly at the valley line. At a ridge line, however, the purlin is produced so that the front edge of the purlin ends at the ridge line. With the 'angle bisector' option both purlins are cut together along the angle bisector.
>
> **End plate**: With the 'End plate' connection both purlins are joined with an end plate. The end plate can be generated according to different criteria. With the options of this connection you can specify which of the two purlins should be notched on the top.

### Rafter roof construction

**Rafter roof construction**: In this drop-down list settings for rafter roof construction can be selected. The settings can be set and saved with the browser button at the right edge of the list. See also [Corbel constructions](https://docs.dietrichs.com/dietrichs-intelligent-documentation/docs-de/~/revisions/CitdvY72ipr2syyO0ESA/konstruktionsprogramm/modellbereiche/dach/dachbauteile/dachbauteile-schwellen-mittelpfetten/knaggenkonstruktion) and [Bearing constructions](https://docs.dietrichs.com/dietrichs-intelligent-documentation/docs-de/~/revisions/Qi3UzV0eQCJtQTRwsbIN/konstruktionsprogramm/modellbereiche/dach/dachbauteile/dachbauteile-schwellen-mittelpfetten/widerlagerkonstruktion).

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

### Other details

**Shortening at verge**: As soon as a purlin ends at the verge during input, it is shortened by the value entered here. With negative values you obtain an extension of the purlins.

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**End machining at verge:** As soon as a purlin ends at a verge during input, the machining set here is attached to this purlin end. Which parameters are used to perform the selected machining can be viewed and changed via the switch at the right end of the field.

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

### Placement of the purlins

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

**All roof surfaces:** The set purlin is generated on all roof surfaces.

**Continuous:** The purlin is generated on the roof surface(s) that were selected graphically.

**Length-limited:** Using two points the length and position of the purlins can be entered. The first point entered also determines the roof surface on which the purlin is to be generated.

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