Connecting an inside corner rail post to the exterior of a rim
joist requires some specific framing and carpentry skill. This is one
way of securing the corner rail post that sits outside the rim joist but
on an inside 90 degree corner.
There are necessary blocking details you have to follow as shown.
The blocking is critical because the inside corner framing has to
be built to take the load from the moment forces created. It also needs a
number of metal structural connectors to hold it all together and keep
the post from moving excessively.
Although corner configurations are more rigid by mere geometry it still important to get the construction details right.
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Required Hardware And Cost
Securing the post this way will work fine. It just brings with it some other railing design issues you have to think about.
Your entire railing sits beyond the edge of the deck. This will
create a gap that you have to ensure does not exceed 4". And remember
to notch the last deck board around each post.
The two biggest issues for most people building deck railing this way is the amount skilled labor to install the blocking and hardware and then the cost.
Additionally, some people are concerned about their posts remaining vulnerable to moisture over the years because of direct wood on wood contact.
If you fall into this camp, there are railing solutions for decks available to get you a high quality and beautiful looking railing.
What you may wish to consider is to build deck railing
with posts that are connected to the deck boards by a low profile
surface mount anchor.
Take for example this low profile internal wood railing post anchor shown here.
At less than twenty bucks, it can be
used in code compliant residential rail applications when installed
according to the manufacuturer's engineering guidelines.
A Simple And Cost Effective Option
This is a proven and very affordable solution for building new wood
deck railings, replacing rotted railing posts, or as support posts for
pergolas, gazebos, decks, etc. on a wide range of surfaces.
Then watch this video of a surface mount wood post anchor that has been tested for use with wood deck railings and costs less than $20 with all the hardware you will ever need and it covers all the possible situations described above.
So there you have it.
A thorough explanation of traditionally building deck railing with an inside corner rail post and an alternative solution for great looking railing. You decide which is right for your specific project.