Mark Brunnr - Thanks for your reply and explanation.I guess I understand the procedure but am not able to visualize the whole picture. I guess I should be able to figure it out as per your description when I will try a trial version just to see how to join them at angles. I guess the post will also first have to be mitre cut at that angle where it meets the beam so that it fits snug to the sloping beam, and then I would make the flat cut into the beam. Thanks for the berm link. I will be posting more questions once I start the trial and then the underground housing build later.