Example parametric assembly: Roof ladder without cage
The following example describes creating a roof ladder as a parametric assembly in Tekla EPM. The example can be helpful when you are learning to create parametric assemblies yourself.
1. Create a description for the parametric assembly

Click New and create an item with the following properties:
 Shape: CO
 Description: Roof ladder (no cage)
 Click Add.
2. Create variables for calculating the ladder length and the number of rungs and collection clips
 Click the Parametric Assembly ribbon tab.
 On the menu, select Parametric Assembly Variables.

Create the following variables without adding default values:
 Overall length of the ladder

Variable Name and Variable Description: Ladder Length

Variable Type: Length – Feet, Inches, Fractions – Meters

 Overall width of the ladder

Variable Name and Variable Description: Ladder Width

Variable Type: Length – Feet, Inches, Fractions – Meters

 Overall length of the ladder
 To close the Parametric Assembly Variables dialog box, click the Close button (X) in the upperright corner.
3. Create side rails

Click New and create an item with the following properties:
 Quantity: 2
 Shape: FB
 Dimensions: ½ x 3
 To create a formula for calculating the length, click Formula next to Length.

In the Formula dialog box, do the following:
 Clear the existing text in the box at the top of the dialog box.
 In the Additional Variables list, select Ladder Length.
 Click Add Variable.

To have the ladder project beyond the landing elevation, type
+ and the length in feet and inches
without a space between.
The formula should now read approximately: [Ladder Length]+3'6.

Click
OK to save the length formula and return to the Parametric Assembly dialog box.
Note that whenever a property is calculated with a formula, it is marked with (F) in the Parametric Assembly dialog box.
 Click Add.
4. Create the rungs
 Click New.

To create a formula for calculating the number of rungs, click Formula next to Quantity.
We want to calculate the number of rungs determined by the ladder length, starting 6 inches above the landing. The result should then be divided by 1'0.

In the Formula dialog box, do the following:
 Clear the existing text in the box at the top of the dialog box.
 In the Parametric Assembly Variables list, select Ladder Length.
 Click Add Variable.
 Type +6".
 Add parentheses () around [Ladder Length]+6".
 Type /12" directly after the right parenthesis.
 Click OK to save the length formula and return to the Parametric Assembly dialog box.

Set the shape and dimension properties of the rungs as follows:
 Shape: RD (round bar)
 Dimensions: ¾"
 To create a formula for calculating the length of the rungs, click Formula next to Length.

In the Formula dialog box, do the following:
 Clear the existing text in the box at the top of the dialog box.
 In the Parametric Assembly Variables list, select Ladder Width.
 Click Add Variable.
 Click OK to save the length formula and return to the Parametric Assembly dialog box.
 Click Add.
5. Create the connection clips
 Click New.

To create a formula for calculating the number of clips , click Formula next to Quantity.
We want to calculate the number of clips based on the length of the ladder.

In the Formula dialog box, do the following:
 Clear the existing text in the box at the top of the dialog box.
 Type CEILING.
 Type the left parenthesis (.
 In the Parametric Assembly Variables list, select Ladder Length.
 Click Add Variable.
 After the variable, type /6').
 To calculate enough clips for both sides, type *2.

To include the first
and last clips for both rails, type +2.
The calculation should read CEILING([Ladder Length]/6’)*2+2. This means that Tekla EPM calculates the total ladder length divided by 6’0, rounds it to the nearest foot, multiplies the result by 2, and then adds 2 more connection clips.
 Click OK to save the length formula and return to the Parametric Assembly dialog box.

Set the shape and dimension properties as follows:
 Shape: FB
 Dimensions: 3/8 x 4
 Click Add.
6. View the result
You can now view the result and test the parametric assembly.
For more information on testing a parametric assembly, see Create a parametric assembly.