The Swamphouse

[Swamp_Yankee]

I got a little bored now that the firepit project is done.  Finally had a great night for it on Saturday and enjoyed some beers by the fire.  Today I started a new project-the Swamphouse.  Since we moved in two years ago I have wanted to build a combination permanent stand, box blind, and treehouse in the swamp behind my pond.  I wanted a large roomy platform that I could build a shelter on, bring my daughters with me in, etc...  Knowing that permanent stands tend to fall apart quickly I started to look at how tree platforms are built for zip lines, ropes courses, and professionally built treehouses at resorts.  One of the biggest things I learned is that when a lot of penetrations are made into a tree in close proximity (ie: banging a bunch of nails into one spot) causes the tree to "compartmentalize" or seal off the injured area and allow it to die.  This is what causes permanent stands to weaken and eventually collapse.  Ropes course platforms and professional treehouses are built using carefully placed bolts in as few locations as possible, as far apart from each other as possible.  With this is mind I started to design the Swamphouse with just four bolts attaching it to the 22" diameter tall straight oak tree near the southeast corner of my land.  The whole platform will be 10' long by 6'-6" wide:

Here's the tree and the view from 16' up:

Building the supports-gusseted with 1/2" plywood, glued and screwed:

That was all for today.  Next will be bolting the 2x8x10 crossbeams to the supports.  I plan to bolt the supports to the tree through the gussets and then (with some help) rotate them upright on the axis of the bolt.  At that point I'll bolt the crossbeams through the center and then it will be time to attach the floor joists.  

Edited October 7, 2019 by Swamp_Yankee

[Swamp_Yankee]

*EDIT* Nevermind-pictures are showing now.

Edited October 7, 2019 by Swamp_Yankee

[Rusty]

Sounds like a fun project.  Keep us posted on your progress Yankee.  

[Swamp_Yankee]

Thinking about building a lightweight frame out of furring strip type wood and stapling something like this to the outside as a shelter:

https://camofabricdepot.com/shop/600d-poly-shadowblock-mossy-oak-break-up-country-60/

[BowhunterNJ]

Cool project!  So one lag bolt through that mitered joint covered by the plywood is enough to support a side from the bottom?  Looks like the bolt would go right through the mitered seam? Glue is stronger than anything for a joint, so maybe that distributed across the larger area with the plywood gives it some extra strength?  

Also what did you use for the sketch/diagram?  That looks useful!

[Live to Hunt]

Pretty cool can’t wait to see it complete

[JHbowhunter]

Good luck. I actually thought this was goi g to be a political reference to the Whitehouse. 

[Lunatic]

I would make sure to look in more depth into carrying capacity of your 1" bolt on top. You also need to worry about the bolt simply pulling out since you are dealing with live tree. I would feel much better if you drilled through the tree and use one large bolt with a nut on both sides. Threaded rod would work very well but again size the bolt to the load. Another concern is that the weight of the structure hanging on one single penetration through the stringer will split the wood. Buying some kind of premanufactured metal seat on which the stringer would simple rest would be much safer.

 

 

Edited October 7, 2019 by Lunatic

[Swamp_Yankee]

3 hours ago, BowhunterNJ said:

Cool project!  So one lag bolt through that mitered joint covered by the plywood is enough to support a side from the bottom?  Looks like the bolt would go right through the mitered seam? Glue is stronger than anything for a joint, so maybe that distributed across the larger area with the plywood gives it some extra strength?  

Also what did you use for the sketch/diagram?  That looks useful!

Google Sketchup-it's like a free amateur version of AutoCAD

2 hours ago, Lunatic said:

I would make sure to look in more depth into carrying capacity of your 1" bolt on top. You also need to worry about the bolt simply pulling out since you are dealing with live tree. I would feel much better if you drilled through the tree and use one large bolt with a nut on both sides. Threaded rod would work very well but again size the bolt to the load. Another concern is that the weight of the structure hanging on one single penetration through the stringer will split the wood. Buying some kind of premanufactured metal seat on which the stringer would simple rest would be much safer.

Also if only one member, the inside stringer, is bolted to the tree, how is the load from the edge,(load moved out perpendicular to the stringer),  transfered to the bolt? It looks unsupported when you move the load to the next stringer.

I am nervous

 

The load will be carried by four 1" bolts, one through each 2x8x10 crossbeam and one through each of the side supports.  Each bolt has a shear strength of about 15,000lbs, so that's not an issue.  As far as pulling out of the tree, I'll be drilling as small a hole (3/4" or less) into the tree so that the threads get plenty of bite.  There will be about 7" of threaded steel penetrating into the tree.  For a large healthy oak tree this should be plenty strong enough.  I did beef up the sides of the stringers with 2x6s on one side of the plywood for exact reason you mentioned.  With regard to the load cantilevered out from the sides, I may end up adding more support once I get it up there and see how it behaves.  If anything, this will end up being way overbuilt-there is likely a way to do it with a much lighter structure that could carry a specified design load in a more engineered and elegant way, but I don't have the know-how to do it that way.  Therefore I'll probably spend a little more time and money overbuilding something that could probably hold my truck up in the air even though it will never see anywhere near that much weight.  

[Kype]

good luck . that loctite glue is good stuff

[Swamp_Yankee]

7 minutes ago, Kype said:

good luck . that loctite glue is good stuff

I'm pretty sure you could build just about anything with PL Premium, 2-1/2" coated deck screws, and enough lumber.  

[Lunatic]

45 minutes ago, Swamp_Yankee said:

Google Sketchup-it's like a free amateur version of AutoCAD

The load will be carried by four 1" bolts, one through each 2x8x10 crossbeam and one through each of the side supports.  Each bolt has a shear strength of about 15,000lbs, so that's not an issue.  As far as pulling out of the tree, I'll be drilling as small a hole (3/4" or less) into the tree so that the threads get plenty of bite.  There will be about 7" of threaded steel penetrating into the tree.  For a large healthy oak tree this should be plenty strong enough.  I did beef up the sides of the stringers with 2x6s on one side of the plywood for exact reason you mentioned.  With regard to the load cantilevered out from the sides, I may end up adding more support once I get it up there and see how it behaves.  If anything, this will end up being way overbuilt-there is likely a way to do it with a much lighter structure that could carry a specified design load in a more engineered and elegant way, but I don't have the know-how to do it that way.  Therefore I'll probably spend a little more time and money overbuilding something that could probably hold my truck up in the air even though it will never see anywhere near that much weight.  

As to my last comment I simply misread your drawing. When I wrote it I somehow did not see there being two lower members supporting the deck above. I though you were just bolting one of the deck beams. The way you have it looks good, 2' overhang is not a problem, it looks good.

I would still drill through the tree, with one bolt across, in fear of the bolt coming out. The bolt is strong enough but is the wood  capable of holding the bolt in? (I see this being used in tree house building applications)

Anyway looks like you did your homework, keep us posted on the progress

[BowhunterNJ]

Can anyone explain the mitered joint with the plywood triangular piece glued over it, as well as the single bolt through the seam of the mitered joint?  Assuming after gluing it has the strength of a solid unit and that mitered seam is moot?

[Swamp_Yankee]

3 minutes ago, BowhunterNJ said:

Can anyone explain the mitered joint with the plywood triangular piece glued over it, as well as the single bolt through the seam of the mitered joint?  Assuming after gluing it has the strength of a solid unit and that mitered seam is moot?

The mitered joint is actually sandwiched between two 1/2" plywood gussets that are glued and screwed.  On the outside of each support I then glued and screwed (with 2-1/2" deck screws) sections of 2x6 (will post a picture when I get home).  The idea is to have a composite consisting of layers of wood solid and glue which, as you said, makes the mitered seam moot.  

[Nighthawk]

You might find some useful information on this site.  
 

https://www.treehousesupplies.com/Treehouse_Bolts_s/41.htm