This is a tiny post about tiny house posts...or joists in this case.
So how do you put loft joists in a tiny sip house? What kind of extra considerations do you have to take and which ones can you ignore? Why is this entire paragraph questions?
When I first looked into building with sips I found Art Cormier and his beautiful house and with his advise my build has gone really well. Be sure to check out Art's blog at tinysiphouse.blogspot.com.
Art told me how he did his joists and I did the same. Basically I cut the joists about three inches longer than the width of the walls from interior to interior. Then I cut corresponding holes in either side of te house through the inside osb layer only. I used a hot iron to scoop out all of the foam out of one of the holes but only an inch and a half of the other side. This allows you to slide the post inside the big hole and have enough room to negotiate the other end into it's shallow hole. When you do this you'll have the post centered with an inch and a half on either side.
With your posts set in place you'll want to fill that void back with foam so from the outside you can locate the spot and drill a small hole that you can use to fill it with expanding foam so you get all the r-value you can and also make that post more secure.
Finally, in order to really secure your post you'll use one of your long SIP screws on each end to drill through the outer layer and into the end of the post. Be sure to let your expanding foam harden for a day or so to stiffen up your osb from the inside. That way your screw doesn't tear it's way through the board as those giant behemoths are want to do.
There is one exemption to this process. The post that is against the back wall is not notched into the wall. This is because at that point in the corner the sip panels have some 2x4s at the seam and I don't want to mess with notching around them so instead I cut it flush, slapped some good ol construction adhesive on there, tacked it up temporary with blocks and toenail screws, then went outside and sip screwed the whole board on both ends and also every foot along it's length. It's not going anywhere.
***One big tip I got from the Artist currently known as Art: once you get your house up and you know it's square measure everything else based on the house. A level can be a very crude tool and isote likely to lead to trouble than a tape measure. A sip house is almost guaranteed to be square once it's up so I measured all my joists based on the house and they look great.***
One hiccup I had was that I had planned on my loft being 8 foot even. This is because it would do a few things; allow a little area in front of the bed for solid footing when getting up and down, make for easy 24 inch on center joists, and I wouldn't have to cut my 8 foot pieces of cedar for my loft surface. And I would have gotten away with it too if it weren't for you meddling kids!...I mean if it weren't for those meddling SIP seams. The sips typically come in 8 foot sections to help keep them a manageable weight but you can get them any way you want, Art got his whole wall as one piece his whole house is 6 pieces and a floor piece. Anyway there was a seam right where my last joist wanted to go and I couldn't give it the same treatment as the first joist so I was forced to concede two inches so my loft is 7'10". Shaq could still take a nap no problem so I'm not complaining.
Because I had to move my last joist I had to make a choice on what to do with spacing. I could space them even, a little less than 24 oc, I could keep the 24 oc for all but te last one, or something else.
I'm doing thin walls, using 3/4 inch tongue and groove boards instead of big 2x4 walls. I'll just need a bit of blocking at the top and bottom to keep them in place and boom, bob's your uncle. I'm planning on using my loft joists to support the top of my thin walls so their placement affects more than usual.
I had planned for my bathroom to be 24 inches wide and already ordered the bathroom stuff to fit so that rules out making all my joists less than 24 inches. My closets were going to be 20ish inches and basically fit between the joists and they have to be at least that wide for my little dog crate to fit so those couldn't move either. I didn't like the idea of making only one joist spacing different so I split the difference on the last two in order to keep as much rhythm as possible. Even if we do all march to a different beat.
Here's the videos: