How to close in rear side of pergola wall?

[damianpc]

Hi. We're looking to wall in one side of a pergola, using stud framing and James Hardi Stria Cladding Smooth. The external side of the wall would face a fence, not be seen at all and (potentially) not closed in. The internal side is undercover. The external side receives very little rain but could get a bit from time to time.

My question is: are both faces, external facing and internal facing sides, of the stria panelling weatherproof? Or would I need to close in the rear side as well, with cement fibre sheeting or similar. 

All timber studs would be H3 treated structural pine. 

Thanks

[MitchellMc]

Hi @damianpc,

I’ve spoken with Hardie’s before about this type of question. James Hardie cladding is specifically designed for use on building walls where the rear side is protected from the elements. It’s not intended for cladding a pergola wall or being exposed on both sides, so there aren’t specific installation guidelines for this setup. It is moisture-resistant but should be coated to prevent water ingress and long-term damage.

At a minimum, I’d recommend painting the rear side to prevent water from soaking into the panel with quality exterior paint such as Dulux Weathershield. If moisture were to get in, it could cause staining or even push off the paint on the front. Ideally, the best approach would be to fully enclose the rear side and include a sarking layer to act as a moisture barrier. This would help protect the integrity of the cladding and ensure better long-term performance. 

Please let me know if you have any questions.

Mitchell