Hanging Joists in Treehouse

[molo]

I'm building a treehouse.

I don't want to set the joists on the beams.

Can I sister a 2"x4" to the beam and set the 2"x8" joists on that?
The beams are sistered 2"x8" that meet code for span.

The beams aren't parallel, therefore I would have to order skewable joist hangers or have a local metal shop make them.

Sistering the 2"x4" is info that I have not been able to find online.

Thanks for any replys. :)

[jimbo]

I would love to see the code that applies to a treehouse!

[molo]

There is no specific treehouse code that I know of.

Some folks have done 1'000s of tests to satisfy CEO's.

The code I referred to is a simple span requirement.

My gut feeling on the sistering of a 2"x4" is that I shouldn't do it. But it can be surprising what the insertion of a specific fastener schedule can do!

Thanks for any replys!

[Southern Man]

I'm building a treehouse.

I don't want to set the joists on the beams.

Can I sister a 2"x4" to the beam and set the 2"x8" joists on that?
The beams are sistered 2"x8" that meet code for span.

The beams aren't parallel, therefore I would have to order skewable joist hangers or have a local metal shop make them.

Sistering the 2"x4" is info that I have not been able to find online.

Thanks for any replys. :)

The 2x4 "sistered" onto the beams (actually called girders in the Code) are called "ledgers". These can be as small as 2x2 (2000 IRC R502.6.2 Joist framing) It doesn't specify the number of nails, but we traditionally face nail the ledger to the girder with a 12d directly below the girder with two more on both sides of the first and 2" away. Make up the remainder of the nailing requirement with 16d toe nailed from the joist to the girder, or better yet blind nail from the first girder ply to the joist.

[molo]

The 10' x 10' "box" on top of the beams will be the house. The front 4' of the beams (12' at the widest point) is where I hope to drop the joists down for a porch that is lower than the house.

What is code on sistering a 2" x 4" in a situation like this?

Thanks!

:)

[Southern Man]

I'm not sure what your specific question is. are you talking about the nailing for a ledger on a 12' span? If so I need the joist spacing.

It looks like you'll need some x- bracing below the floor to keep it from swaying.

[molo]

The front 4' I want lower than the joists sitting on the beams.

I figure I need a hanger (skewable from Simpson, or locally made) or I can use a "sistered" ledger to get the joists for the front deck lower.
Please note: In the pic. the front joist has not been added in, hence the look of the rim joists not having a joist to "close" the box.
I honestly don't know the code on using a ledger to sit my joists on. The width of the beams at their widest point (which will be the front of the deck) is 12'.

Thanks for the help! :)

[Ian Gills]

Damn squirrels are getting very sophisticated these days!:)

[hj]

quote:
When I retire, I am going to take it easy and become a commercial plumber. If I get really good, I might turn residential. :)

And if you get extremely good, you MIGHT be good enough to become a service plumber.

[jimbo]

It's a damn tree house. You can do anything you want. The tree will probably outlive anything you do.

As far as sistering a 2X4 onto the 2X8..why not? I assume you would do that with through-bolts. A ½" bolt every 18" or so....that would hold any load you could get up into the tree.

[Cookie]

http://www.treetopbuilders.net/consulting.html

[Cass]

I wonder how that would have held up witth the winds we had last week.

http://local.cincinnati.com/local/pg/photogallery.aspx?sid=1&gid=300253

[master plumber mark]

It's a damn tree house. You can do anything you want. The tree will probably outlive anything you do.

As far as sistering a 2X4 onto the 2X8..why not? I assume you would do that with through-bolts. A ½" bolt every 18" or so....that would hold any load you could get up into the tree.


Tree houses are a lot of hard work.. a
nd you can basically do anything you want to do.......

I built one about 3 summers ago.....

getting that load of wood up into the tree was great fun....
I used treated wood only......and bolted everything together



It looks like you got a pretty good start...


The only thing I would suggest is not to bolt anything to the trees..... I dont care to stress or kill the tree.

you are not high enough in the tree to worry about wind
blowing the house like a sail, but still the movement of the trees in a good storm can really shake up the structure.....


I myself would install some 4x4 beams into the ground with concrete......

and you can always add more later

I concreted the treated 4x4s into the ground and built up from there....


maybe if you are lucky I will post a pic of my high tech tree house.

[Cass]

I am sure you installed a tankless heater...:)

[jimbo]

I am sure you installed a tankless heater...:)

For sure, tankless is the way to go, so you don't have to beef up the joists to support the load of a tank!

[Southern Man]

The front 4' I want lower than the joists sitting on the beams.

I figure I need a hanger (skewable from Simpson, or locally made) or I can use a "sistered" ledger to get the joists for the front deck lower.
Please note: In the pic. the front joist has not been added in, hence the look of the rim joists not having a joist to "close" the box.
I honestly don't know the code on using a ledger to sit my joists on. The width of the beams at their widest point (which will be the front of the deck) is 12'.

Thanks for the help! :) I suggest that you re-read post 4.

[master plumber mark]

My tree house went through the floods of 08 and survived


actuallly my tree house looks more like an outhouse on stilts.....


but its fun to go sit out on the overhang to the creek and drink some beers.

on a hot summer night..



http://onsmartpages.com/weilhammerplumbingco/nss-folder/pictures/si_UEw80h80_DSC07678.JPG (http://onsmartpages.com/weilhammerplumbingco/pictures/view_alone.nhtml?profile=pictures&UID=10292) http://onsmartpages.com/weilhammerplumbingco/nss-folder/pictures/si_UEw80h80_DSC08170.JPG (http://onsmartpages.com/weilhammerplumbingco/pictures/view_alone.nhtml?profile=pictures&UID=10291)

[molo]

I suggest that you re-read post 4.


Southern Man,

Thanks for taking they time to reply to my unconventional questions.

I'm not going to bombard you with code questions, because it seems it can go on forever! Rather I just found the NYstate building code on the Department of State site. I'll spend some time with that.

Regarding the 2" x 2" that seems real small and I wonder what kind of load is allowed.

Also, I've read today on a reputable treehouse builders site (michael garnier) that joist hangers aren't recommended for treehouses. They recommend the joists on the beams. I'm guessing this is because of the movement and that also may be a concern with the use of a ledger, (unless I doubled up a 2" thick board, but that's another code question).

Do you have any suggestions for connecting the joists that are sitting on the beam to the beam?

Thanks for any replys! :)


Also, nice treehouse MPM! Looks like that creek decide to expand a bit.

[Thatguy]

To give you some reassurance you might look in
http://www.amazon.com/Basic-Lumber-Engineering-Builders-Schwartz/dp/1572180420/ref=sr_1_1?ie=UTF8&s=books&qid=1222812879&sr=8-1
and other books like it. These principles should be "the mother of all codes".

[Southern Man]

Southern Man,

Thanks for taking they time to reply to my unconventional questions.

I'm not going to bombard you with code questions, because it seems it can go on forever! Rather I just found the NYstate building code on the Department of State site. I'll spend some time with that.

Regarding the 2" x 2" that seems real small and I wonder what kind of load is allowed.

Also, I've read today on a reputable treehouse builders site (michael garnier) that joist hangers aren't recommended for treehouses. They recommend the joists on the beams. I'm guessing this is because of the movement and that also may be a concern with the use of a ledger, (unless I doubled up a 2" thick board, but that's another code question).

Do you have any suggestions for connecting the joists that are sitting on the beam to the beam?

Thanks for any replys! :)


Also, nice treehouse MPM! Looks like that creek decide to expand a bit.

Live loads are 30 pounds per square foot, dead around 5, for a total of 35psf. With a 12' span and 16" joist centers, each end needs to carry 280#.

The nails are the limiting factor. Most pressure treated lumber is southern pine, so with 12d common nails in side grain the allowable load is 94# (1.63" penetration), for 16d common it's 108# (1.78" penetration). Toe nails are de-rated by 5/6 and nails in end grain are de-rated 2/3. 12d common nails are 3" long and 16ds are 3.5" long. The connection type may also require a reduction if the length of the nail in the penetrated member is less than the required penetration. The critical length is the member with the point end in it, not the head end.

A 2x2 ledger with (3) 12d nails will carry (3)(87)(1.5/1.63)= 240#. The joist has to be back-nailed or toe-nailed to keep it from rotating, which will more than make up the 40# deficit.

[Southern Man]

With these light loads and at least a 2x8 joist you can as an alternate back nail with 16d common nails from the first ply of the girder to the end of the joist. The allowable capacity is (4)(108)(2/3) = 288#. The highest nail should be 2" or more below the top of the joist, and the lowest nail at least 2" from the bottom of the girder, and 1" from the bottom of the joist. The remaining should be between and no closer than 1" apart.

This is a more difficult connection since you have to hold up the joist while you nail into it.