# Treefort / treehouse structural integrity



## syler (Feb 23, 2009)

I'm building a treefort/ treehouse for my 2 boys and am nervous about the structural integrity of it.

I'm using 2x6x8' braces on 2 pecan trees that are 11' apart. The braces are secured with 5/16" lag screws. The 2x6x12' joists "float" on top of these braces to allow for the tree trunk growth.

Is the 11' span for the joists too much? Would blocking help?

Will the 2x6x8' braces fail?


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## Willie T (Jan 29, 2009)

I see three things that concern me.


What is joining those two trees together? I see six joists that appear to be just nailed to the diagonally supported cross pieces. The cross pieces may stay well attached to the trees, but will not the joist ends pull away if the trees separate from wind movement?
The diagonals appear to be toe-nailed to the bottom edges of the cross supports. Some notched joinery is called for in instances like that... some way, better than nails, to lock those joints together. It may be there, but I can't tell.
Although lagged to the trees, the bottoms of those diagonals could benefit from some method of tying them together, even if it is just a plywood plate across both faces of the diagonals.
Other than those 3 nit-picks, it looks like a very good start for a neat treehouse.


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## syler (Feb 23, 2009)

*Thanks for the reply, Willie T.*

So, the 11' span of the 2x6 joists is not a problem?

1) The floor joists are "floating" on the cross braces that are bolted to the trees. I'm using metal brackets to keep the joists in line and to prevent the floor from falling off the ends of the cross braces. The brackets are nailed to the cross braces but not to the joists. This should allow for the joists to slide while the trees sway.

2) The diagonals are connected to the cross braces with 1 lag screw. I could add a plywood piece to secure the connection.

3) I'll take your advice and use plywood to secure the diagonals to each other. Sort of like this photo?...


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## Willie T (Jan 29, 2009)

Yeah, shudda been 2 x 8's, but you're right in there for the light load you'll be supporting. Might be a bit springy, but probably no danger of collapsing.

I know we built them that big, and bigger when I was a kid... and did it out of patched together 2 x 4's and whatever we could find.

I might double up the outside joists since you'll have a wall there.

Both plywood additions sound good.

Don't know where you're located, but if lifting loads from wind storms are an issue, you dont want that thing ending up on your own roof. Might consider that.

This should be fun for you: neat treehouses


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## syler (Feb 23, 2009)

*Uh, oh... wind storm.*

I live in Houston, TX... recently hit hard by Hurricane Ike. 

In case of hurricane, I might have to quickly secure the whole thing with steel tie-downs or something.

I'll use your suggestion about adding another 2x6 member to the outside joists.

Thanks for all of your help.


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## Tom Struble (Dec 29, 2008)

that looks cool show us some pics when your done:thumbup:


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## DangerMouse (Jul 17, 2008)

perhaps some heavy logging chains bolted to the trees or sunk in 55 gal. drums of concrete and mounted to the outer frame would help hold it down in a heavy wind? leave some links hanging to allow for growth adjustments. the kids can climb the chains too.. fun fun!

DM


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## skeeter 152 (Nov 17, 2008)

too much adult thought going into this tree house.throw away the level square strait edge plumb bob laser etc. and get the crayon print from the kids


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## Scuba_Dave (Jan 16, 2009)

One of the most interesting kids pre-made forts/houses around here are made totally out of level, walls at odd angles, weird roof line


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## syler (Feb 23, 2009)

*safety first...*

I know I'm being a little anal, but I'm only being anal with the structural support. Once my nieces and nephews visit, I'll have 10 kids jumping, climbing, swinging from this thing and I don't want anyone to get hurt.

I promise, once the support is done, my 2 boys have tons of ideas for useful stuff they want on, in, under, around the treefort. Like...

a pulley system
tire swing
trap door with cargo net
rock wall
a moat with sharks... yeah, my 6 yr old is getting a little carried away. I mean, come on, sharks? Maybe alligators, but not sharks!

What other cool add-ons am I forgetting?


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## Willie T (Jan 29, 2009)

syler said:


> I know I'm being a little anal, but I'm only being anal with the structural support. Once my nieces and nephews visit, I'll have 10 kids jumping, climbing, swinging from this thing and I don't want anyone to get hurt.
> 
> I promise, once the support is done, my 2 boys have tons of ideas for useful stuff they want on, in, under, around the treefort. Like...
> 
> ...


A mock steering wheel (ship-style) for pretending it's on the water.

A flag pole so they can hoist their club flag.

A fireman's pole.

A slightly higher vantage point for the "lookout" to perch.

A carved wood name plate.


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## DangerMouse (Jul 17, 2008)

helipad on the roof...
solar powered, batt. backup lights...
chemical toilet...
solartube on roof for free light.....
built-in covered desk for quiet homework area....

DM


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## Treehouse Guy (Feb 10, 2011)

syler said:


> I'm building a treefort/ treehouse for my 2 boys and am nervous about the structural integrity of it.
> 
> I'm using 2x6x8' braces on 2 pecan trees that are 11' apart. The braces are secured with 5/16" lag screws. The 2x6x12' joists "float" on top of these braces to allow for the tree trunk growth.
> 
> ...



I agree with Willie T, but I'd also add that 5/16 bolts are suspect to me - once repaired a treehouse attached like this - the braces on one tree had snapped the 5/16" bolts. The other side was okay. But it was only 2 years old. Upgrade to a 1/2" or bigger galvanized lag bolt for more security with kids up there... The treehouse bolts I sell are probably too big for this application, but you can find 1/2" and sometimes 5/8" at Home Depot or Lowes.


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## tpolk (Nov 7, 2009)

3/4" all thread thru the tree, also 1/4" cable from up in tree to outside of triangle joist support with turn buckles for adjustment


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## WillK (Aug 29, 2010)

syler said:


> I know I'm being a little anal, but I'm only being anal with the structural support. Once my nieces and nephews visit, I'll have 10 kids jumping, climbing, swinging from this thing and I don't want anyone to get hurt.
> 
> I promise, once the support is done, my 2 boys have tons of ideas for useful stuff they want on, in, under, around the treefort. Like...
> 
> ...


Ill tempered sea bass?:laughing:

Periscope. Trebuchet. Maybe use chalkboard paint on some of it?


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