Well I have been lurking around this site for years now and i am finnaly going to post some of the work i have done. My wife and i finally purchase some property on the key penninsula in 2009. we wanted to build a house there but over time have moved the start date back and i have settled for a treehouse/shed/cabin. I have learned alot since i started but i think i need some critique from some people who know more. Here are some photos of the property and the start of the building process.(https://i184.photobucket.com/albums/x193/chapman0929/IMG_3660.jpg)(https://i184.photobucket.com/albums/x193/chapman0929/IMG_3663.jpg)
first stages(https://i184.photobucket.com/albums/x193/chapman0929/IMG_3664.jpg)(https://i184.photobucket.com/albums/x193/chapman0929/IMG_3665.jpg)
I don't know what your design is but from what I can see, you need a LOT more bracing. Here is a structure I built. It isn't finished. I have quite a bit of bracing and it does wiggle a bit. I don't have any confidence problem with it though. But you can see all the bracing I used and I used very large lag bolts to secure everything. Nails will not do by themselves. Just my two cents so far.
(http://www.ouramericanadventure.com/coppermine/albums/userpics/10001/DSC_0140.jpg)
that looks really cool. how tall is it and what is the footprint? I did wind up bracing it some more. Ill post some pics and let me know what you think.(https://i184.photobucket.com/albums/x193/chapman0929/phonepics182.jpg)(http://://i184.photobucket.com/albums/x193/chapman0929/phonepics183.jpg)(https://i184.photobucket.com/albums/x193/chapman0929/summer472.jpg)
A lot of the lumber came from an old garage in Port Orchard that someone listed on craigslist for free. The teardown took me 3 days and some hard work. It wound up costing me $300 for fuel and the dump fee for the shingles. It was well worth it, i got alot of siding and sheating as well as 2x4 and 2x6. If only i had taken a picture of it before i tore it down.
I haven't built a house that high, but I have built decks similar to that. Don't mistake me for a real engineer or architect, please, but here's my concern----once you get some walls up and create a nice sail, I think your structure will twist in the wind. You have good compressive strength with your posts and your cross bracing is good diagonal support, but if you imagine a giant hand grabbing the top of it and twisting it, the entire stilt structure will bend from a rectangle to a parallelogram. Your floor you have down does provide some sheer against this but only if you are really, really secured down to those cross beams---more than just a couple of Simpson ties. I would add a giant 'X' joining diagonal corners, or at least some 45 degree braces in each corner (as high as possible, just below the floor).
Thanks flyingvan, you make a good point. That will be an easy fix and I will get right on it.
Frankly, the height of those posts scares me. Then I went back and read instead of just looking at pictures. I see Port Orchard mentioned. Port Orchard, WA? Earthquake country.
The USGS database shows that there is a 93.255% chance of a major earthquake within 50 kilometers of Port Orchard, Washington within the next 50 years. ... note that probability is for a 5.0 quake; for lower intensity quakes the probability interval decreases and the percentage chance approaches 99%. That probability risk is much higher than the area in NM where our cabin is located and I am having thoughts about it and it only sits on piers that extend 13 inches above ground level.
That data is pulled from this website (http://www.homefacts.com/earthquakes/Washington/Kitsap-County/Port-Orchard.html) which gets the data from the USGS
Let me add that I am not an engineer. I know one who would be quite concerned about that, to put it in the mildest possible language. If that was a simple uncovered deck, it would cause enough for concern, IMO. Erecting walls and a roof on top of that is going to greatly increase the effects of wind upon the structure, not to mention seismic activity. It is my belief that the plan needs some serious rethinking. That is my opinion, not an engineers opinion as I stated, but I believe a valid opinion.
Also note that even though the IRC allows a post size of 4x4, the current Prescriptive Residential Wood Deck Construction Guide (http://awc.org/publications/DCA/DCA6/DCA6-09.pdf) recommends 6x6 as a minimum post size for decks.
If it were me, and I know it is not, I would consider enclosing that entire lower area with wall framing on 16" centers. Then nailing sheathing over the entire exterior, making a ground level shed out of that bottom. Framed and sheathed walls with the sheathing well nailed into the posts and the framing infill would make each wall able to resist much greater forces.
Anyhow that is one opinion. I don't want to appear to be a wet blanket, but I can not sit by without commenting on my perceptions.
My structure is 17' fro ground level and is 12x24 in size. I think there is a valid point about twisting at the bottom. My posts are 3' in the ground and surrounded and supported with concrete to keep the legs from pulling towards each other. In your case, a set of sturdy boards at the base surrounding the entire structure and then in the inside to keep every board from not only kicking outward, but also inward. I am no engineer either, but this is what my work has taught me. I believe my structure would be stronger if I put some cables going from the bottom of 1 corner to the top of another corner and then replicated on the other corners. My structure doesn't wiggle a whole heck of a lot but it does wiggle. I would be concerned a little by your base not being in the ground but rather, setting on the ground. There is nothing preventing it from tipping over in high winds. All this in my opinion. I had originally planned to have posts buried in the ground and attaching to the top of the base legs with "guy wires". Ultimately, I don't believe it is needed in my case. It might not be a bad idea in yours.
Just some food for thought. There will be a few others chiming in, like MountainDon, who are far more smarter and "engineering wise" than I to offer more opinions.
It is fun building though isn't it? :)
Just to tack on to the subject of earthquakes---I'm on a federal team and have responded to a few....If you have a brick structure, versus a tent, guess which is more likely to survive? The stiffer the structure the more prone to damage it is. Earthquakes seem to leave the rickety stuff alone (They leave them for the hurricanes) probably because they flex around some.
I like the cables and guy wires idea
Quote from: phalynx on February 19, 2012, 12:17:43 AM
I believe my structure would be stronger if I put some cables going from the bottom of 1 corner to the top of another corner and then replicated on the other corners.
That could help but would also take away from the use of the space under the floor.
Maybe that's a good thing (taking away from the usefulness) as then there woule be less chance of someone being under it when it collapses.
Quote from: phalynx on February 19, 2012, 12:17:43 AM
I had originally planned to have posts buried in the ground and attaching to the top of the base legs with "guy wires".
Guy wires from the top of each post down to some hefty concrete anchors could also help. As someone I spoke with about this said though... there in a chance for injury from running into a guy wire. He broke his nose as a kid by running into a guy wire.
There is no doubt in my mind that a tent would survive an earthquake better than most other structures. However, IMO, one can not extrapolate that data to a structure like this, and call it a safe structure.
I had another look at the images. Am I correct that the structure appears to be sitting on what are commonly referred to as deck blocks? The deck blocks appear to be simply sitting there on top of the earth? I think that must be correct as the ground is not disturbed enough to have made a hole in the ground and pour concrete. That did not register in my brain the last time I looked; I think the stilts got the best of me.
With a structure on top of that that becomes so easy to be overturned by strong winds. Do not count on the weight of the building counteracting lateral wind forces. This is especially a concern with a top heavy structure.
My earlier comment about building walls using the lower perimeter should now be modified... I was under the impression there was some concrete in the ground. d* That does not seem to be the case. A single storage shed can get by sitting on the ground or deck blocks. But a second floor, especially a highly raised second floor... ? The shed could shift and maybe fall off it's blocks. But my impression here is that if the ground shakes the upper floor whips around and falls on whoever/whatever is on the ground.
Port Orchard is right in the worst seismic risk area in WA state. That alone, IMO, should be cause enough to rethink what id being built here.
And of course, there is always the possibility that a quake or wind strong enough to cause severe damage might not come along in my lifetime, your lifetime, or the kids lifetime. At least things like tornados and hurricanes are usually given ample warning and people can stay away from dangerous areas. But nobody is good enough to predicting date and time of an earthquake or how strong it might be.
Anyhow that's what I have to say. There is information available about building in a seismic area. Pretty much all I have seen regarding construction is seismic zones centers around keeping all the parts together; keeping any one component from failing from too much flex. This is the world on the engineer or the world of following prescriptive solutions that have been derived from engineering analysis.
I appreciate all of your input on the structure as it sits right now. I do enjoy building but I wasnt really thinking about earthquakes as i have yet to experience one for myself. What sort of modifications would you suggest? I decided to use the deck blocks because of their ease of instalation and i had seen them used in the western wa area. the treehouse is 11x17 and it will be about 21 feet tall when finished. Any more insight would be greatly appreciated since i plan on it lasting a long time.
I agree with the others.
I'd be looking to tower designs.
This is no endorsement just some quick searching.
http://www.water-towers.com/
http://www.fs.fed.us/database/acad/lt/
Would it take care of most of the racking issues if you walled in the back bay to make a stogage area?
Phalynx, do you have a thread on this forum which shows your structure being built in the above picture? I'm very interested to get ideas on this thread as I bought river property last year http://countryplans.com/smf/index.php?topic=10161
If and when I build it will likely be at least 12 feet or more above ground level (inside the flood zone on the river). I plan to overbuild (only do it once). I've given it a great deal of thought. Why drop time and money into something that might disappear with the first flood or hurricane. Even if I've only got $3,000 in the structure... and it goes down. That's still $3,000 I could have put into a $7,000 build that might last the rest of my life.
Don't take chances with mother nature. In the very least I'd say use 6X6's buried in the ground 3" supported beneath by concrete/gravel footer. Then fill hole with 2 feet of concrete. Then cross brace as recommended by mtnDon and others on here who've been around here for awhile.
When it comes to a structure like this. The most important part is the foundation IMO. In this case the posts/piers are part of the foundation.
Granted I'm still the village idiot when it comes to building. I'm still just too inexperienced.
Here's my shed I posted on here recently http://countryplans.com/smf/index.php?topic=9948
When I framed up the walls I failed to install a top plate. And I should have used 2X6 rafters. I'm still just a rookie, but I've spent a lot of time contemplating this type of build.
Some resources.
http://www.boardwalkbuilders.com/pages/art/art1.htm
http://amazingplans.com/styles/beach-pilings.html?plan_foundation=4550
http://www.topsider.com/Piling-pier-stilt-foundation-home-plans.asp
what do you think about building forms around the perimeter of the deck blocks and pouring a concrete pad up to the 4x4 posts? that would tie everything together but it still could move in the event of an earthquake. Do you think that enclosing the bottom area will still help or shoud i take it all down and pour some footings? :-[ Im just not sure of how to attatch the house to the ground.
It gets worse
(https://i184.photobucket.com/albums/x193/chapman0929/summer475.jpg)
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Yes, it does.... d* Well, go ahead and post all of them.. Go ahead and take your licks now.. ;) We need to know how far you got so we can see where changes can be made.. It won't be bad. I have seen much much worse.... in fact, I may have built much much worse...
Let's see how far you got.
Ok fess up is it finished yet ? :o
here's a possible remedy
rent a hole auger dig 4 feet down between the existing pads ie 6 new holes 12" diameter site a paver or gravel in the bottom fit 6 off 6x6 treated posts into those holes running down from your beams and backfill with cement
wait for setting
remove the existing posts - dig out the 4 end positions and repeat.
spacing is uneven but you'll have a firm foundation -brace as per recomendations
Uh Oh. You guys are on to me. I have gotten alot further than these pictures show. :P
(https://i184.photobucket.com/albums/x193/chapman0929/summer471.jpg)
(https://i184.photobucket.com/albums/x193/chapman0929/summer603.jpg)(https://i184.photobucket.com/albums/x193/chapman0929/summer601.jpg)
(https://i184.photobucket.com/albums/x193/chapman0929/summer605.jpg)
(https://i184.photobucket.com/albums/x193/chapman0929/summer594.jpg) (https://s184.photobucket.com/albums/x193/chapman0929/?action=view¤t=phonepics200.mp4)
here are a few more. i had alot more pics but they were on my phone and it broke
(https://i184.photobucket.com/albums/x193/chapman0929/summer596.jpg)
(https://i184.photobucket.com/albums/x193/chapman0929/summer597.jpg)
(https://i184.photobucket.com/albums/x193/chapman0929/summer721.jpg)
Getting up to speed.
(https://i184.photobucket.com/albums/x193/chapman0929/summer847.jpg)
this tree fell 2 feet from the treehouse on the north side. scary
(https://i184.photobucket.com/albums/x193/chapman0929/summer849.jpg)
then i had to start cutting alot of them down since there was no root to them at all. the neighbor said they are prone to falling down so i have quite a few more to take down but i got all the ones on the west side so I should be good for a while.
(https://i184.photobucket.com/albums/x193/chapman0929/summer846.jpg)
"then i had to start cutting alot of them down since there was no root to them at all. the neighbor said they are prone to falling down"
This is what we've been trying to tell you - your tree house has no roots ! ;D
I would not let my children play under that tree house!!!
Har Har very funny, :D
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.
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
(https://i184.photobucket.com/albums/x193/chapman0929/summer1047.jpg)
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(https://i184.photobucket.com/albums/x193/chapman0929/summer1052.jpg)
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
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.
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?
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.
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
Quote from: flyingvan on March 20, 2012, 10:04:32 PM
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.
(https://i139.photobucket.com/albums/q305/djmbucket/construction/framing.jpg)
Quote from: brian7gv on March 16, 2012, 10:38:12 AM
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.
Quote from: Don_P on March 21, 2012, 07:51:09 AM
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.
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. d*
I have alot of braceing on the long axis but still looking for options on the short side.
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The stairs are up and useable. I still need some pressuretreated treads and some more braceing but its way better than a ladder.
(https://i184.photobucket.com/albums/x193/chapman0929/IMG_0188.jpg)
Burn season. There is alot to do
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