Hi all. First post, please bare with me. I have afew questions. I am going to build a pergola on my patio, it’s triangular in shape. Approx 4m centres for 3 post. My patio is 40mm concrete slabs on 150mm type 1 and a sand cement screed. I think I will have 150x150 post but I would preferably like to fix these with bolt-ons (post shoes) Is this advisable? Also, with the span from post to post being 4m, i don’t want it to sag so will 8-2 be sufficient for this, or is this overkill. And then I will be having 6-2 on top. Any questions and advise greatly appreciated. Many thanks, Ben.