Hi @Stephalbert,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
If you’re looking to hang a swing porch chair from your pergola, it’s really important to make sure everything can handle the load safely. The waling plate, which is attached to the fascia and supports the pergola rafters, transfers weight to the roof truss overhang. But how much weight that setup can handle isn’t straightforward and is something that only an engineer is qualified to make determinations on.
The truss overhang is mainly designed for roof loads and not for additional weights like a swing. When you add a swing, it introduces both static (the weight of the swing and the person using it) and dynamic loads (the motion of swinging), which can stress the truss in ways it wasn't meant to handle. That’s where getting an engineer involved comes in. They can tell you exactly how much extra load the truss can bear without risking structural issues.
Given that swings can exert a lot of force, especially when in motion, you want to be extra careful. It’s a good idea to consult a structural engineer to evaluate whether the current setup can accommodate the swing safely or if you need to make any reinforcements.
Let me know if you have any further questions.
Jacob
