Ideally you should find the rafter first underneath the sheathing locate by feeling the nails.
How to use post for roof.
Place a hydraulic jack underneath the roof near the damaged post.
Measure the distance between the top of the jack and the roof.
Cut two 2 by 4 boards with a circular saw that are 2 inches shorter.
Then attach the tool into rafter by driving couple of 16d nails.
Once both of the brackets are secured set a post into them.
Measuring posts for a freestanding roof differs in only one respect from measuring for a house attached roof with the attached roof you ve already defined the roof height at the ledger line.
Once it is plumb mark the position on the porch roof.
Roof jacks make it easier to set roofing and increase safety for you by providing stable surface.
Install another bracket in this position.
Stand a post up in the bracket and hold a level on its side.
For a freestanding roof begin with the corners and then erect all of the intermediate posts.
Here s what to do.
The main structural members of patio and deck overheads are posts or columns and beams which run from post to post or from post to ledger.
Use 2 inch carriage bolts to secure the posts to the mounting brackets.
Minimum sizes of posts and beams are set by engineering requirements and are strictly governed by local building codes.
Repeat this procedure so that all the columns look exactly the same and have the same dimensions.
This post and beam design is secured with a post cap.