Attaching Railing Post to a 4x8 Beam and Flush 2x8 Joist

by Leo
(Kirkland, WA)

4x8 Beam and 2x8 Joist Connection

4x8 Beam and 2x8 Joist Connection

I am rebuilding a front porch with composite, and reusing the framing. The framing connects 2x8 joists to a 4x8 beam directly. Most of what I see puts the framing on top of the beam, so my first question is:

Can the joists be connected to the beam directly?

Second, I want to attach my 4x4 railing posts on the corner between the joist/beam, but the joists are attached using hangers that do not allow me to have the post flush to the joist/beam surfaces.

What is the best and safest way to attach my railing post?

Can I have it bolted only to the joist and not through the beam? I would like to avoid having to drill through the beam.

I've attached pictures the beam/joist connects, as well as what I am thinking of doing to attach the post, assuming I can find a way to get it flush to the beam/joist surfaces.

Editor's Comments

Yes the joists can be connected directly to the beam. This is common floor deck construction. Just keep in mind that the integrity of the entire joist and deck is now reliant upon the joist hangers and their connection to the beam. This means if you are using ACQ lumber to make certain you use hangers and screws or nails that have enought hot zinc (or stainless steel) to perform will over the life of the structure.

Because you have a large 4" beam and you wish to secure the posts withing the framing and the joist bays, the posts will be set back at least 4" from the edge of the deck. So you will lose a little bit of surface area. But it will be secure.

Bolting through a 4x8 beam will certainly be sufficiently strong however you should use large flat washer under the lock washer and nut. Yes you would drill through the beam to do so and should use a 1/2" hot zinc coated carriage bolt. The flat washer prevents the nut from being pulled into the beam if the post were subjected to extreme load.

Alternatively you can use 2x8 cleats and "scab" then to the beam and joist just behind the posts. This is very effective. The Simpson hardware is also a suitable solution. One or the other is going to be fine. Both would be overkill but you are going to be fine.

Examples of Joist Connecting Railing Posts

There are dozens of detailed illustrations showing all the framing techniques and hardware options in an article I wrote which I think you should also take a look at. You can peruse through them and find the one you think pertains best to your deck.

However the one drawing that seemed to most closely relate to your deck is the post along a joist. Take a look and examine it for yourself.

Surface Mounted Post Anchor Solutions

Sometimes a surface mounted post anchor solution is the perfect option if you can live with the maximum height and spacing recommendations of the manufacturer. But this kind of solution gives you total freedom as to where you may locate each post. The Titan Wood Post Anchor™ is one such solution and is a very affordable option for one and two family residential dwellings.

Alternatively, the manufacturer Titan Building Products is coming out with a very interesting new product called the Titan Structural Wood Post Anchor™ which is engineered for maximum performance and maximum beauty. It is a truly concealed post anchor and is smaller than the cross section of a 4x4. It connects to wood posts so no need to cover it with a post sleeve - you can actually show off a beautiful wood post from 36" to 72" tall. Yes, you are not limited to 36" or 42" post heights like structural steel posts. And it performs in the same range as a structural steel post. So this opens huge design possibilities for builders and homeowners. It can span distances greater than 6'. The manufacturer says 2018 is the launch date.

So those are some of your options.

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