I have a 22 ft long and 12 ft wide carport which is supported on one side by the house and ties in to my roof.

The three metal posts which support the roof have either rusted out at the base or have sagged causing the roof to droop on one side. I have removed the posts and built a temporary supporting wall.

There wasn’t an obvious beam supporting the structure, and the posts were tied into double rafters. Once I removed the soffit material I found capping the rafters are two end beams but are not continuous pieces.

What I am planning to do is to add a lengthwise 4×4 beam and use four 4×4 posts. I am currently digging holes for 8 inch concrete sonotube bases extending down to the frost line and try and bell them out at the base to add more surface area on the clay soil.  

Is this sufficiently strong enough?