Cabin loft extension

[memopad]

I'm hoping you guys can help me determine if my plan of action is reasonable or stupid!

I have a loft in my cabin that spans 12ft. The loft joists are full dimension 2x8 16" on center, tied to wall studs with a jack (king?) stud underneath. 

My dilemma is that I've decided an extra foot of loft space would allow me to turn my bed 90 degrees and make the layout much more workable. Since I've already finished the interior with tongue and groove pine, it would be fairly difficult to access the wall studs to add another joist that way.

My idea is to run 2x4s perpendicular through the existing 2x8's, and cantilever a floor extension out about a foot. These 2x4s would bore through the 2x8s and hold up another 2x8 at the end so I could run the floor out that extra distance. Sorry if I'm using the wrong terminology and this isn't clear.

I would not attach stairs or a ladder to this extension, I would make a trap door through the floor on the opposite side and run a ladder through that.  

Stupid idea? Or something that would be good enough to hold the foot of my bed?

[memopad]

I'll try and add a couple of photos of the loft floor...

[Don P]

No, and those joists do not need injury. From here I see 3 I would have culled for spike and oversized edge knots. If they make #2 it isn't by much and red pine is probably close in 2x8 at 12'. That said it is not going to be heavily loaded. 

This is a graphic of the notching rules there;


 

For others reading this but using heavy timber:
A note on a note in that first graphic where it says a 1/6 depth notch on the bottom, tension, edge if the lumber is 4" thick or less. Heavy timber does not allow any notching on the tension edge.

I don't believe there is a concealed rough sawn hanger. If you can weld I'd make this and use structural screws into a stud, get a long 1/8" or 5/32" bit and predrill for the screws.
LUC Concealed Flange Light Face-Mount Joist Hanger | Simpson Strong-Tie (strongtie.com)

Depending on floor layout you might be able to end one end of the joist supported by stairs or ships ladder rather than a hatch. Then you just have one end with a hanger on the wall or a 2x nailed to the wall under the joist... hmm if it notched around the joist it could form the wall post beginning of the guard rail at the loft edge.

[memopad]

Thanks for setting me straight on that idea Don. 

The joists are cut from Jack pine, some of the first things I cut after I got my sawmill. They definitely aren't the highest quality lumber I've produced  ;) The loft floor boards are primarily jack pine with some red and white pine mixed in. There is barely standing headroom in the loft for me, but I haven't noticed any amount of sagging or movement while walking around up there. It's definitely not a high load area.

My backup plan for adding another joist without cutting open the walls was to install two "posts" flush against the wall supporting the ends of the joist and running down to the main floor. I thought this might look kind of stupid but it's probably the most realistic way to go.

Or, I'll just leave the loft as is and start planning a larger cabin 2.0 build. This cabin is 12x16 that I built on a whim starting the end of October 2020. I had to clear a foot of snow to get the footings down but got lucky with a really warm November that gave me time to frame it in. This is in North Central UP of Michigan, 1000ft above Lake Superior right in the middle of a snow belt. Average snowfall at the cabin is probably in the 250-300" range.





 

[Don P]

That is cute as a button. That's it, I kept thinking, but it has to be red, not thinking about jack. Yeah, the rafter load had me more concerned than the floor load, you are probably wearing more up top at times than the floor ever will. We applied small half tree posts to the wall of one cabin, in that case they were stiffeners but would be fine posts if that fits in the theme better, although at 12x16, small prolly wins the day.