Pergola batten sizing

[Emaitchess]

Hi all, hope someone can help us out.

We are planning to build a pergola with "rafters" spaced at approx 1400. We want to include shade battens on top (no other roofing/shadecloth) and are wondering what minimum size batten would span that distance. The battens will be laid on their edge for greater strength, and we'll use hardwood.

Thanks

[silentC]

If they're not supporting anything, I don't think it really matters - unless you plan to walk on them. It will be more a factor of how much shade you want from them.

As a guide, for a 1200mm span (1400 is off the table - it would be too wide probably if you were using roof sheet) you would be looking at between 38mm x 50mm and 50mm x 75mm, depending on the timber you choose and the batten spacing, and you would install them wide side down, not on edge.

[Emaitchess]

Thanks very much for this - that's what I was hoping to hear. You don't think full exposure to the elements would warp timber of this size too badly? And while it would be more usual to fix them flat side down, can you see any problems in fixing them on their edge?

Thanks again

[Trav]

It is pretty common to see 40x40 or 50x50 battens - usually in treated pine because it is cheaper. There shouldn't be any problems with warping or placing them on the edge. You will need to oil etc as you would with any decking timber.

Depending on how big the pergola is, you could be up for some serious $$ for the battens if you space them closely. That's why people tend to use TP or at least place them on flat.

Trav