Exterior Railing Posts Attached To Rim Joist
Exterior railing posts are typically the most commonly observed method of attaching posts to decks.
The post is notched and bolted externally from the outside through the rim joist.
To do this properly, ensure that the post is level from the front and sides by using a level and shims between the notch and the rim joist.
The first and most obvious way to install railing posts is to attach them to the exterior face of the rim joist.
First determine the spacing between posts, never more than 8' and usually between 4' and 6'.
Cutting Posts
Cut the railing posts to length. The total length includes the overlap on the rim joist, the building code minimum railing height and any extra for a protruding post cap (if desired).
For a deck (24 to 70 inches above ground) railings must be at least 36" so the total post length would be 42" to 48".
For a deck (70 inches or more above ground) railings must be at least 42" so the total post length would be 48" to 54".
Notch Posts to Fit Exterior Rim Joist
Use a 4x4 post and cut a 1.5" x 6" notch out of one side of the post.
To stiffen the rim joist where the post will attach, insert another piece of 2x8 or 2x6 behind the rim joist and between joists. Or attach another rim joist to the outside of the deck frame.
Either of these options will stiffen the outer edge of the deck where the post will attach.
Drill And Bolt
Predrill between 2 and 4 holes (1/4") through the front face of the railing post and the notch. Set the post into position on the rim joist and using the holes as guides, drill through the rim joist.
Securing Exterior Railing Posts to Joist
To secure the post in place, position the notched post on the rim joist and check for level. Use cedar shims between the notch and the rim joist as required to achieve level from the front and side views of the post.
Since the posts will be exposed you should take advantage of that and make them a part of the railing design feature. Try miter cutting the bottom of the post to make it more attractive or use stainless steel nuts and bolts to enhance the look.
The Final Effect on The Railing
Exterior railing posts will tend to pull your eyes toward them. Consider using decorative caps to complete the look. The downside to this kind of a railing is that the balustrade will sit beyond the periphery of the deck. Keep this in mind as you design your railing.