1. ## How to calculate load bearing steel plate

I have two posts in the attic which are holding the roof, as you can see in the Existing.pdf.
The post on the right is supported by an horizontal parallam installed on the ceiling
(not shown in the picture). I need to remove this post.

The solution is to install two parallams on the roof, as shown in New.pdf, and to transfer
the load to the bearing wall 6 ft to the right. I need to brace the parallams with a steel plate.

To ease the installation and fabrication, I can split the steel plate in A and B, separate pieces,
held together by C, one piece. Both ensembles twice, one on each side of the parallam.
The steel plates are shown bellow the parallam for clarity, but will be installed right on the joint.

The roof point I am trying to solve is shown by the arrow in the 3D picture.
The roof is Presidential synthetic tiles, pretty light. The drawings have the correct scale.

If somebody help with calculating the dimensions of the parallam and the steel plates I would
greatly appreciate it.

2. Have you tried asking the Parallam people? They would know the properties of their product better than anyone.

Are you running long bolts right through the beam and the steel plates, as in 16 bolts in total?

The snow loading and wind loading for your area would be required. This sounds more like a job for a local Engineer than a faceless Internet "expert," me included.

The advice from here, and any other Internet site, while it may be well-meaning, is only as good as the price you pay.
Big costs at stake if you get it wrong.

3. Hello mbeffa and welcome to the forum -
If you will do some detailed searches of the forum archives you will find that this is a very common type of question. "I want to change the structure of my house or a building in some way. All I need is some help with the calculations or advice how to proceed." Unfortunately the advice you will get on this forum is pretty consistent - you should consult a professional engineer that is familiar with the building codes and practices in your area. This is a critical part of your family's home. You don't really want to depend on some information you got for free on some forum. We have some VERY GOOD and VERY SHARP people here, but the information may very well be worth what you paid for it. The best engineers on this forum will not address your question because they are familiar with the risks (both physical and legal) involved.

But please don't let that discourage you from hanging around and contributing to other discussions.