I am going to build a treehouse for my family. The simple (hopefully) design is at this site:
http://pages.areaguides.com/ubuild/TreeHouse.htm
My question is, this calls for a 8 inch diameter post (tele pole) – which are impossible to find in Michigan. What I can find is 6×6 posts. If I reduce the lumber dimensions (ie 2×10’s become 2×8’s, etc) can I build this on a 6×6 post? It seems like more that enough size to carry the platform and a few kids but I am concerned about lateral pressures. Is treated 6×6 plunked into the ground going to be near as strong as a cedar post?
I don’t know any engineers and hate to turn this into a huge project when it seems pretty straightforward. I do realize that a square post will cause me some grief when attaching the 45 degree supports but think I can manage around that.
Thank you for your comments!
Jack
Replies
Sorry, forgot part of question. If a 6x6 isn't strong enough can I glue, nail, screw 4 - 4x4's to create an 8x8?
thanks again.
I don't think I would trust a 6x6 for that kind of design. Did you try the electric or phone co. to see if they had any post. Maybe even a railroad yard would have something you could use. What about a 8" log that was treated for underground use.
I don't think I would trust the 4 4x4's glued and screwed either. Instead I would use a 4x4 post in each corner.
I must admit that I haven't built a treehouse with just one single post in the center like that so maybe some who has will have a better idea.
Dave
I bet you can get your 8" diameter post from any of the Michigan log home manufacturers listed in this link:
http://loghomelinks.com/states/mi.htm
a bit of sleuthing should score you a hunk of Black Locust tree - - lots of them in Michigan, rot resistant and heavy - - - or the electric company - here I would talk to our REMC, they'll sell me a pole, deliver and plant it - -
Thanks for the feedback. Unfortunately these log home builders are primarily in the UP or at least northern part of the state. I tried Consumers Power and got puzzeled responses, maybe I will try that again.
Is it the type of wood (Cedar) vs. Oak that will make the difference or dimensions? An 8inch diameter post will have roughly 50 sq/in and a 6x6 36sq/in.
I can't find an 8x8 that are any length and need 18-20 ft.
Personally I don't like the 4 poster, looks like a hut on sticks.
I would love to hear from an engineer...
thanks.
perhaps an engineer will chime in - -
in my opinion, you've got at least 2 considerations - - enough strength not to break like a toothpick; I believe this factor is a function of the square of the diameter in addition to species - - another is the ability to stand without wallowing around in the hole - there's going to be great stress from wind - I see nothing to keep the post from rotating and the only thing keeping it from leaning is the fill in your post hole - - frankly, I don't think an engineer would sign off on those plans...
"there's enough for everyone"
I'm an engineer and I'm chiming in. But I'm not a structural engineer, my expertise in this area comes from 1) building treehouses for my son and 2) knowing more people (three) who live full-time in a tree house than any poster here. Okay, I really only know one tree-house dwelling dog musher and two of his girlfriends, but still. . .
Why not just bolt five 2x8s together? You'd have a 7.25 x 7.5 post that would have some redundacy because of alternating grain. Easy to get in whatever length you want.
The peak loads would come from wind (how windy does it get there?) and from lots of people if they get in one corner and jump up and down.
Rather than butt the 45s to the vertical post, I'd lap them over a flat face. Better to have the foot of overlap for a bolt pattern than to try a make a butt joint secure.
If an adult is ever going to be in treehouse, have enough headroom to standup somewhere inside. That helps your comfort a lot.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Thank you David!
I like the idea of bolting together 2x8's but some of the feedback wasn't too positive. Do you think 4 2x8's is better than 4 4x4's?
I will pick a spot behind some Pine Trees so hopefully this will block some of the wind.
I like five 2x8s better than four 4x4's because you only have to bolt in one axis instead of two. And you have 11% more cross section. But mostly for the easier bolting.
Four 2x8s would be a bit less wood. And then you're trying to figure out which way the prevailing winds are (so the thicker axis can be in that direction). I'd spend the extra $20 for the fifth and have an almost square post.
How old are the kids? Or is this for you?
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Hey, David
That wouldn't happen to be Gus Gunther out in Clam Gulch would it?
We worked together for Blazy Const. a few years ago.
Dave
Dave,
How many tree-house-dwelling Iditarod-running guys are there on the Peninsula who go only two weeks before landing another girl despite the broken nose, feral look, and a week since his last shower? Yes, I'm referring to Gus.
Two of my wife's partners (MDs) helped him build his treehouse (it's featured in several books). I played soccer with him and liked employing him at my place till he went and got a real job in construction. He once ran for mayor of Clam Gulch. And regularly wins the weekly ping-pong tourament.
His treehouse has been on a couple of TV shows and afterwards he gets mail addressed to "Gus, Calm Gulch, Alaska" asking for advise on how to quit the rat race, his hand in marriage, etc.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
One of the guys said that it was featured in a magazine but when I asked him about it he acted like it was no big deal.
The last time I seen him was about a month ago. He was on the payphone with his latest, (Canadian girl that he met in a hostel in Europe), at Mom and Dads Grocery in Sterling. He said that he joined the Carpenters Union and was working in Anchorage.
We always had the best time working together. I liked to mess with him when he was doing something. I would walk up behind him and say stuff like "huh, never seen it done like that before" and then walk away. Man it would tick him off. Then he would get me back later in the day usually in front of everyone. He's very quick witted.
Dave
The visiting medical residents at my wife's practice get a loaner vehicle while they're in town for a month. For a whole year, the Bronco had a cassette tape stuck in the radio. So no tunes except the tape. And the tape was a audio love letter from Gus to his girlfriend (in Costa Rica?) at the time. A love-starved, dog-mushing, tree-house dweller's rambling to a girlfriend. Doesn't get much worse than that.
Everyone else can take Dave and David's tales of Gus as a warning if they start to think living in a treehouse full-time is a good idea. It takes a very unusual person to do that.David Thomas Overlooking Cook Inlet in Kenai, Alaska
LOL to that.
Thanks! Treehouse if for the kids, ranging from 4-15 years. Oh, and the deer that wander into my yard!
If you can get friendly with your local utility guys, you can usually talk your way into a broken/cut/removed pole. I remember my father did that when they replaced the guy pole across the street, because they needed to put up a full height pole to service the house that was being built there. The guy building the house wasn't too thrilled when they put the pole in our backyard, since he just assumed he'd get to keep it......
Well, I'm going to chime in here like a wet blanket with a pessimistic attitude. I would seriously question the author of that DIY article to see if that design has ever been built. The first sketch shows the tree house wrapped around a tree...looks good. Then he proposes to put an 8x8 only 4 feet in the ground (5 feet if you can dig that far he says) and attach a very top heavy structure. Here's one of the clues that makes me laugh at his proposal: in order to dig the hole deep enough, he suggests that you tape extensions onto the handles of the post hole digger so you can reach farther down into the hole. Pray tell, what kind of tape is going to be strong enough?
The reason the real tree works is that it has roots that go down into the earth, and also spread out to the drip line...that's quite a bit of underground material, and that's what permits trees to resist twisting and overturning forces.
I am concerned that you are going into this with way too little experience and too much Pollyanna. The first thing you've done is tried to downsize the post from the suggested size, and from your questions I don't think you have a clue as to the properties of different sizes of lumber. To answer one of your questions, yes the species of wood makes a lot of difference in it's strength. An oak post would be substantially stronger than cedar, which I would not even consider using.
If you're determined to build this thing, do yourself...and you family...a big favor and buy some time from an architect or engineer. And then walk away from Home Depot, go to a real lumber yard, and I'll bet they can order anything you need...but the chances are that the 8x8x20 won't be on the shelf, so ask questions at the order desk.
Sorry for the negative response...I like to push the envelope lots of times....but it soundds like you're about to break it.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Ed
he suggests that you tape extensions onto the handles of the post hole digger so you can reach farther down into the hole
Man I had to laugh when I read that!
Doug
Ed,
I was thinking about the same thing as you were.
My thought would be to use at least a 10" diameter Ash post (should be able to get a good deal on it now in Mich). You can buy and apply your own preservative. Also, I'd get someone out there to auger the hole about 36" in diameter at 48" deep (forget about those stupid post hole diggers!). Fill it about half way with concrete to secure the post.
With a hardwood post and a monolithic base, you will never have to worry.
gk
Yeah, the post 4-5 feet in the ground is bogus and I was going to comment on the extension handles on the post hole digger but it seemed so obvious. But here goes: Post hole diggers are difficult at the limit of the normal range. Making the handles longer is not viable unless you are very desperate for another foot. But I'd want a depth similar to the height of the whole thing, depending on soil conditions.
The easier way to dig a deep hole with a shop vac. Loosen the dirt with the lightest thing you get results from (sharpened 2"x2", electrical conduit with the end flattened, steel digging bar, etc). And put a 10-foot, 2" PVC or ABS extenison on your (big) shop vac. Works sweet.
The best utility clearance I've seen done was an industrial version of that - light jack hammer with LONG extensions. And a truck-mounted vacuum with a big drop-out chamber for the dirt. They could go to 6 or 8 feet in 2 minutes. And therefore see and measure EXACTLY where the utility was instead of those +/- 2-foot spray paint marks.David Thomas Overlooking Cook Inlet in Kenai, Alaska
I like the idea of bolting 5 2 x's together but I think I would glue in between them as well. Bolting more than 3 or 4 doesn't really work as well as you might think because the bolts get too long and you get this sheering action as the members slip by each other. So I would go stright for the epoxy and glue the snot out of them then bolt. The bolting would hold the whole assembly together well and the epoxy would prevent sheer or slip.
As a side note though..... one 8x8 post doesn't really sound like big enough to me. I don't think I'd be sending my kids up in that.
Good luck
Rob Kress
Rob, I know that a 6x6 has a 10 ton rated capacity according to the UBC. I've lent out my copy so I can't look up a 8X8 but I'll bet it's more than that evan at 20 feet!
I stand way corrected
Rob Kress
You aren't wrong regarding stability! It's gonna take a whole lotta concrete to keep that thing up in a stiff wind!
... I know that a 6x6 has a 10 ton rated capacity according to the UBC...
ya but... this installation needs consideration of tensile strength - - dead load is about the least of the considerations"there's enough for everyone"
the only real load that a 8x8 can't handle on something as small as a tree house would be the stability factor!
without a massive amount of concrete to hold it down a tree house like this would easily topple in a stiff breeze let alone high winds.
Sail boats that survive hurricane force winds have masts this size. thus the strength issue isn't a factor while the stability issue most definately is!
Sail boats that survive hurricane force winds have masts this size.
ya, but they furl the sail in high winds - this tree house plan puts a big sail on top a modest post - a decent blow would snap it like a toothpick if it didn't lay it over first...(IMO)"there's enough for everyone"
It's realitively easy to figure out the force that would be needed to break the beam holding it up. surface area times the wind speed ... but why bother. It'll tip over long before the post breaks..
MY question is why have it that High? Is there something magical about being twenty feet in the air that you don't get from being on the ground? Why not just build the kids a neat fort and all sorts of hidden doors etc..
I'd worry evan if I could build it, that some kid would want to climb around on the thing fall off.
>> It'll tip over long before the post breaks.
Not if it's installed correctly. I have seen power poles quite a bit larger than 8" that broke off before they tipped over. And the sail area of the wires they carried was little if any larger than this treehouse. Although somewhat higher, I'll admit.
>> Is there something magical about being twenty feet in the air ...
Um, yes. Keep saying things like that and we'll conclude that the pod people have taken the real Frenchy and left a substitute who was never a boy. :o)
>> I'd worry ... that some kid would want to climb around on the thing and fall off.
Not building it won't prevent that. If there's no tree house, they'll climb around on the tree. If you cut the trees down, they'll climb around on the house. If you threaten them with grievous bodily injury for climbing on the house, they'll go to their friends' houses and climb around on their tree houses / trees / house.
I speak from extensive personal experience. At age six I was climbing around in a tree, several feet above our tree fort, and higher than the roof of the house. I sat me down on a dead limb and the bark slipped, launching me into the void, or that's the way I remember it. Broke both arms midway between the elbow and the wrist. My subsequent reluctance to climb trees lasted until both casts were off.
Some years later we had another family over for Sunday dinner. About five of us were big enough to walk around, and the other family had about as many ambulatory. After dinner the parents were sitting around the table talking grown up talk, or trying to over the din, and one of them finally noticed that they had seen something like 7,000 miniature persons run shrieking up the stairs and none of them had come down. We were going out a bedroom window onto a narrow ledge, stepping over into a tree and coming down the tree. Back in the house and up the stairs.
You might be able to keep kids from climbing on things if you hobbled them, but then the other kids would tease them mercilessly at school.
Dunc-
You are always such a realist.
OK! now we get to argue ;-)
Actually I can't believe I wrote that bit about kids falling.. Must be getting to be a geezer ;-(
As for tipping over I still claim that if you put a post 4 feet into the ground it will likely tip.. if you put a bunch of guy wires you'd better make sure each one is capable of handling the wind load since it's possible that only one wire will take the strain..
>> I still claim that if you put a post 4 feet into the ground it will likely tip.
Very likely. 4 or 5 feet into the ground might work, in the right kind of soil and with meticulous backfill technique, but I wouldn't build it that way. The rule of thumb I'm familiar with is that 1/3 of the length of a heavily loaded post or pole should be in the ground. Given the weight and sail area of this tree house, I might argue for 1/2 the length. So start with a 24 or 30 foot post instead of 20.
Another interesting thing about the plan as drawn is that the elevation view shows a pole much larger than 8" in diameter. If you scale from the lengths of the sides, it looks to me like somewhere between 16" and 20". If you built it that way and started with a pole long enough to install correctly, there would be no question of it either tipping over or breaking off, and no need for guy wires. The only remaining failure mode in wind would be the superstructure tearing away. You wrote sometime last year or the year before that your house was built to withstand tornado force winds, so it shouldn't be too difficult to detail a treehouse to handle anything up to about 100 MPH.
And to think, i just wanted to build a neat structure for my kids.
I appreciate all of the input. I now am convinced that I should build a sandbox. Hopefully they won't choke on the sand.
>> Hopefully they won't choke on the sand.
Probably not, but what about the diseases they might catch from the cat dung? :)
That was an excellent response. Not because we swayed your decision, but because you didn't come back all fired up with an attitude. Obviously you don't belong on this forum :)
There has been a lot of suggerstions given here, some good, some worthless...and I know mine was the best. Seriously, if you want the tree house, we can help you design it so that it will be buildable and useful. Maybe you could use four 6x6 posts, spaced about 4 ft apart as a core for a 12 ft platform. That way the overhang is only 4 feet, and the core could contain the ladder/steps. And kids don't need to be high...anything over an adults head puts them in a position of superiority and another world, so a platform height of 4 to 6 feet would work.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Ed,
You pretty much described what I was planning. I already have a sandbox.
I had planned on the posts at the corners of 8x8 platform but really like the cantelever (sp?) option - more tree-like. If I understand you correctly, I can mount each post on a single floor joist vs. bolted in corners. Do I need to put in additional support where the post meets that single joist?
I apologize to everyone for my ignorance. Just a white-collar father trying to learn.
Jack
I would treat it as two seperate supports, like two goal posts, each with a 6x6 sunk well into the ground...the crossbar would be two 2x's...one on each side opf the post with substantial through bolts. Wait...use 6x8 for the posts, turned sideways, notch the top of the 6 inch side a full 1-1/2" to allow the 2x to have full support...with about 4-1/4" between them...still use heavy bolts. 6x8 PT is available at my Lowes and HD off the shelf. Then you could either use joist hangers to carry floor joists the other direction, or even better lay full width joists on top of the two cross bars, with solid bridging to keep the joists from rollong over. Basically you're building an elevated deck.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Unfortunately these log home builders are primarily in the UP or at least northern part of the state.
big truck?
JeffBuck Construction, llc Pittsburgh,PA
Artistry in Carpentry
A friend of mine cut a good sized tree that was growing in his back yard, cut it off at about 8 to 10 feet off the ground.
Then he built a big tree house on the stump. Sits up there in the eve's and drinks beer.
Doug
I installed my own electric pole here. Bought the pole, brought it home, cut it off, stuck it in the ground, and put the box and mast on it.
For the pole, I simply went to the lumber yard and asked for a utility pole.
It is a standard sized pole, treated the same as any telephone pole. Tapered from about 16" to about 10" in 30 feet. I cut ten feet off the top.
Pole cost me about 300 dollars. But it is identical to the pole at the street, and will last just as long.
If you do nothing, nothing will happen.
Go to a sawmill and have them cut you one! it's gonna be a lot cheaper than anything you get at a lumberyard!
Michigan has a lot of trees, there are small to medim sawmills all over the place.. you might rethink building it with local wood rather than plywood etc.
It'll be a lot less expensive!
a lot!
Jack,
I built a very similar treehouse, only I used 6 x 6 posts at the corners. Without the center post you can put a tire swing or sandbox under the treehouse. I went with the tire swing and the kids love it.
Good Luck
Mike K
Amateur Home Remodeler in Aurora, Illinois
Forget that 4 2x8's stuff. You DON'T want to build a health hazard in your yard for your precious children to play on. You need a utility pole about 16" at the base for this unit. Think if it were a tree, you wouldn't want to build this on a 12" tree (let alone an 8 incher). The required stiffness for this design is pretty high. If you cant get such a pole DON'T build it! Such utility poles are available wherever utilities are available so you just have to find the right place to get them. Ask around. Check with electricians, cable companies, power companies, local telephone companies, etc. Four 8 x 8's and you might be talking turkey but the utility pole will be cheaper and easier to get (this is a standard size or even toward the small end for such poles). This might be a twenty foot pole but 5 feet are buried ... leaving 15 feet ... and the roof will take up at least 3 feet ... the platform floor should end up about 6 feet from the ground. This will be good, high enough to give the right feeling but offering the likelihood of survival in case of falls. I might be tempted to make the floor a foot higher so as to offer headroom beneath and avoid causing a hazard for people on the ground. Good luck! It should be fun!
PS: I am not an engineer but have an instinctive sense of proportion based on many years of experience in carpentry ... and I did study engineering in college. You'll find that the better carpenters have a pretty fine sense of appropriate design, often superior to that of architects and designers. Most engineers are pretty sharp and build in ample safety margins too so their recommendations are usually accurate. Wherever a skilled carpenter and an engineer disagree you will be wise to go with the most conservative recommendation (ie; strongest).