Is it possible to buy framing that's rebated for tongue and groove

[pedr0]

Where can I get timber that is pre-rebated to accept tongue and groove?

I'm planning to build a small bike shed, basing the design off a neighbour's. It's made with tongue and groove and the tongue and groove boards slot into rebated framing members. It looks very similar to this.

Can you get tongue and groove 'systems', which have different sizes of timber that is already rebated to accept the tongue and groove? E.g. in the picture above, the corner posts are probably something like 40x40 with a rebate on two sides only. While the framing around the doors might be 40x30 with a rebate on the narrow edge.

 

[foxhole]

Will have been custom made . Just cut the lip off the t&g and butt up to frame .