We sometimes field questions about how you should go about calculating the capacity of a bracing element with a varying wall height. The answer is covered in NZS3604:2021 in clause 8.3.1.4; 

8.3.1.4 Adjustment of bracing elements for height 

(a) For wall bracing elements of heights greater than 2.4m, the bracing rating determined by test or from table 8.1 shall be multiplied by: 2.4/element height in metres. 

(b) Walls of varying heights, shall have the bracing capacity adjusted in accordance with 8.3.1.4(a), using the average height. 

This is commonly seen with mono-pitch roofs with a skillion ceiling; 

Fixing a Bracing element that spans a ceiling apex: 

When a bracing element follows a raking wall and spans the apex of a gable end it is best to use the GIB Ezybrace® fastener pattern at the apex as this helps to transition the forces in the linings around the corner. 

Two reminders: 
1) keep the perimeter 90mm free of any cutouts and
2) ensure the minimum part sheet width of 300mm is achieved including at the top of the raking bracing element. 

And as always if you have any questions call the GIB® Helpline 0800 100 442