I have a porch switch installed onto a 4x4x12 beam, and the beam has developed a crack that looks ~1 inch at its deepest, and ~4ft long. The wood beam is screwed into equidistant perpendicular 2x4s with 6 inch screws, so they should have gone ~1.5 inches into the 2x4s that are above the cement fiber ceiling. I used the same screws to attach the swing hinge to the 4x4.
Does anyone know what I should or can do to prevent this crack from continuing further and how to fix the issue if possible?
That's not cracking. It's checking, and all timbers do it. It's what happens when wood dries out. Wood expands and contracts across the grain, and unless it's dried over extremely long periods in controlled conditions it's unavoidable.
It's not a concern as it doesn't affect the bending strength of the member significantly. This assumes that your mounting screws go nearly or completely through the timber so they're not just hanging on the partially detached portion.
your mounting method is incorrect, doing it that way will crack the wood every time, over time especially swinging on it. So either don't swing on it, or do your swing mounting like this that won't cause that kind of splitting:
it's not soley "checking", not with how his swing mount is on the end and the bolting of the 4x4 up into the ceiling is inwards away from the end, with the forces at play. The swing mounting is at least exacerbating the "checking".
from his pic this looks like what is happening :
This depends a lot on what is above the 4x4.
Given the fastener positions, it looks like you have 2x4 (or greater) trusses and the 4x4 is lag bolted to them. What's odd here is the lag bolts stop at the closest swing anchor in your photo. I guess whomever mounted it considered it to be good enough that the swing appears to anchor into the porch joist.
See if there's another joist on the other side. Then add a couple of lag bolts. If I were you, I'd take the 4x4 down and replace it while you're at it. Wood glue is amazing, but I wouldn't want to bet on it fixing that board enough to support a 2 person porch swing.
Please rethink this entire installation.
The 4x4 needs to be supported on both sides of both chains.
The screws look too small. I can't be sure from pictures of course, but are they meant to support swinging weight hanging from the upside-down heads like that?
Those plastic hangers and those little baby riveted hinge pins just, nope!
