Looks like you're located in South Africa, is that right? Not sure what lumber species you typically have access to, but this house used a #1 Grade Douglas Fir. Douglas fir typically comes from the US or Canada [more specifically from Washington, Oregon, or British Columbia]. It's a fairly rot resistant wood, and structurally very strong with a Modulus of Elasticity of around 1,800,000 and a fiber bending stress of 1,200 up to 1,500. I often bolt the double members together, but here they are connected with steel drift pins.

What lumber species do you typically use?

Hi! Yes, I am in a coastal region of South Africa. I was interested to see, as we import so much of our timber for construction, (mainly Meranti from Malaysia - which is a rainforest timber and not a sustainable solution in the slightest). I am doing a similar detail on a house at the moment, and am using Grade A South African Pine. Most of our structural timber is out of Pine, Eucalyptus and Saligna. I will post some pictures of the home, once its done in a few months.