Space boarding timber

[MrA.G.]

What sort of timber is the best compromise to use for space boarding. Hardwood would be great but probably out of our price range. Presumably most of it is just treated softwood?

Also, any tips as to how best to fix it and protect the timber cladding rails supporting it? I was thinking of nailing a bit of wide DPC across the top of the rails and clamping it down the face between the rail and the space boarding.

 

[Forever Fendt]

22X150MM treated timber softwood nailed with 65 Mm galvanised clout nails no need for the DPM it will do more harm than good