200 sqft treehouse

[brian7gv]

Har Har very funny, 
Just got back from the property, did alot of burning and planted about 20 trees. mostly fir and some cedar. Had alot of fun.

By the way the kids run around like crazy on the top floor and it hardly moves. i think you are a worry wart. im a bit concerned about the earthquakes still but i will remedy that come summer.

[brian7gv]

Thats the last of them so far. I do have a set of stairs built but no pictures yet. i will keep working on that

[Bob S.]

I like your build. Did you build it up for the view? If so could you show us a pitcure of the view? Thank you for taking the time and trouble to post it on the forum.
Bob

[Bob S.]

The reason your build intrigues me is that my county in Idaho does not requier a building permit for anything under 200 sq ft. I plan on building a 12x16 foot with a loft just like you have and using it as a guest house after I build my cabin. I am having a lot of problems figuring out how to put in the stairs. I will be 70 years old this fall and do not want a ladder.

[brian7gv]

I wish that there was a view. its just a wooded area. the only reason we built it up was that we were going to but it in a tree like a real treehouse but everything i looked  at made me think that it would shift alot over time. I didnt want to hassle with any permits either so im glad some areas allow for the buildings under 200 sqft. Some of the rules make things difficult though, no heated space and the loft has to be less than 5.5 feet tall. but thats fine for sleeping. a stairway to the loft on a 12 x 16 will be very challenging. there just isnt very much floor space. are you going to put in a kitchen or bathroom?

[Bob S.]

I plan on using  jefferson stairs like Beavers did in his build (12 x16 House) and tucking a bath under it. I think if I put the toilet under the stairs it will make good use of the space. No kitchen.

[flyingvan]

  Brian---I have another structural concern for your build, but fortunately there's a solution.

   Over time, or even a single heavy snow load (if that's at issue there) or a heavy branch comes down---your ridge will want to settle and push your walls out, particularly in the middle of the structure away from the end walls.  There are three things that keep a roof from pushing walls out--- First is a heavy ridge pole (the main roof beam) that is supported by columns on either end of the house.  Then your rafters can just rely on the strength of that beam to always keep things straight.  You don't have that.  Second, if you have ceiling joists at the top of the walls before the gable, they keep the walls from pushing out which keeps the roof from settling.  Your layout doesn't allow for that.  The final approach is with collar ties--- horizontal members that join the rafters, forming a strong triangle that can't spread the rafters out.  This option's still available to you.  The lower down you make them, the better, but you're limited by your window placement. 
   I would take 2x6's, cut angles matching your gables on both ends, and size them so they end up just above the top of your windows (with room for the finish, of course)  It'll give a bit of flat ceiling, a great place to mount some small halogen recessed lights, too

[MountainDon]

The final approach is with collar ties--- horizontal members that join the rafters, forming a strong triangle that can't spread the rafters out.  This option's still available to you.  The lower down you make them, the better, but you're limited by your window placement. 

Under current IRC nomenclature, technically they would be called collar ties if in the upper one third of the rafter pair triangle. If they are in the upper third they do not do much to prevent wall top spread. Collar ties are meant to hold the upper portion of the roof together, to prevent wind lift from peeling the roof apart at the peak.   If located in the lower one third of the rafter triangle they become rafter ties and are effective at preventing wall top spread. Note, if wall tops spread the ridge sags; just an FYI.  Rafter ties are best when they are actually ceiling joists as flyingvan mentioned. Note though, that as the rafter tie moves up from the wall top they place additional stress on the rafters. The rafters themselves may have to be increased in size depending on how far up the triangle and on other design loads. The IRC rafter table footnotes have the details on how to resize the sizes listed in the tables.

The good thing this is a smallish narrow structure so the loads are nowhere near those on a 20 foot wide.

Also good is that the dropped loft floor is not dropped very far down the wall studs. Looks like less than a foot. That greatly reduces the bending stress on that short upper end of wall stud. Again, being a smallish narrow structure is a partial saving grace when it comes to that.

My primary concern is still the fact that the structure is highly elevated with what I characterize as rudimentary bracing.

[Don_P]

I wish that there was a view. its just a wooded area. the only reason we built it up was that we were going to but it in a tree like a real treehouse but everything i looked  at made me think that it would shift alot over time. I didnt want to hassle with any permits either so im glad some areas allow for the buildings under 200 sqft. Some of the rules make things difficult though, no heated space and the loft has to be less than 5.5 feet tall. but thats fine for sleeping. a stairway to the loft on a 12 x 16 will be very challenging. there just isnt very much floor space. are you going to put in a kitchen or bathroom?

A little bit on that exception;
It is intended for accessory structures rather than habitable buildings.
1. The building eave height is 10' or less
2. The maximum height from finished floor to grade does not exceed 18"
3. The supporting structural elements shall bear on firm soil, and if wood, shall be preservative treated.
4. The structure is anchored to resist wind loads
5. The structure shall be of light frame construction.

Here nor there but I don't want others taking an incorrect notion away. This would not be an exempt structure. I do agree with other folks' structural concerns.

[MountainDon]

A little bit on that exception;
It is intended for accessory structures rather than habitable buildings....

Every jurisdiction may have their own wording. My state rules make it very clear what their intent is with the first item in their list of what types of projects are exempt from the permit process....

1.  One story detached accessory buildings used as tool and storage sheds,
playhouses, and similar uses, provided the floor area does not exceed
120 square feet.

[brian7gv]

Thank you for everyones input. I did wind up putting hurricane straps on both ends of every rafter. Where it meets the ridge beam and where it sits on the wall. I also put a large lag bolt with a chain between the outside walls just below the loft floor. I did have some issues with wall spread during construction so this chain became a permanent fixture.

To the issue of Storage and accessory buildings, I am violating a few of the county rules with reguards to building with out a permit. Mostly that they arent supposed to be over 1 story and not heated. But each area of the country has their own set of rules to follow and propper research should be done prior to any projects beginning. Im willing to take my lumps if need be.

Thanks again for eveyones time, More bracing is on the way.

[brian7gv]

I have alot of braceing on the long axis but still looking for options on the short side.





The stairs are up and useable. I still need some pressuretreated treads and some more braceing but its way better than a ladder.


Burn season. There is alot to do