A couple of the more obvious objectives when building a treehouse are:
- Make sure the structure is safe and sturdy, and
- Don’t kill the tree
Grunt Like a Caveman
Well, it turns out one of the ways you accomplish those laudable goals is by minimizing the number of penetrations through the tree’s outer living layer of tissue. That means fewer connectors, which also means bigger connectors. And when I say “bigger”, I mean grunt-like-a-caveman-with-your-new-weapon bigger. Our weapon of choice for the main attachment points to the tree is this beauty – a 1-inch diameter x 14-inch long lag bolt.
Being trained as a mechanical engineer, this sort of over-sized monster hardware appeals to my primal need for high safety factors and bad-ass equipment. (sorry for the language L&A, but sometimes Papa’s gotta call ‘em like I see ‘em.) It also gives my kids something heavy and dangerous to play with when Mom’s not looking. And it’s a nice conversation piece when guests are over:
Me to other guy: “Dude, check this out!”
Other guy: “Awesome!”
Wives: “You idiots…”
More Hardware Fun
Luckily our treehouse design comes with some additional perks for the specialty-hardware-loving engineers/dads/nerds like me. You’ll recall from a previous post that we have a front beam that will be suspended by cables attached to the tree above. This nifty feature calls for quite a few pieces of additional specialty hardware. Galvanized steel cable, thimbles & clamps, turnbuckles, shackles, forged eye bolts, load plates, and so on. It’s like Christmas for an engineering nerd…or a redneck (they have a surprising number of similarities).
Where I Bought the Stuff
Unfortunately, monster lag bolts and hardware pieces like these are not available at your neighborhood Ace Hardware store. So thank goodness for Internet shopping. There are a number of professional treehouse supply websites that sell all sorts of specialized hardware, massive lag screws, etc. But good golly they are pricey! (and I am notoriously frugal) I’m sure these sites are run by fine folks who know what they’re doing, but $35-$40 per bolt just seemed silly to me. So after considerable scouring of the web, I came across a couple sources that deserve a mention and a ‘thank you’.
Lippincott Supply in Vallejo, CA - http://www.lippincottsupply.com/
These folks carry lots of specialty fasteners. I got all of my large bolts, washers, and nuts here. At about $8 per bolt for the 1-inch x 14-inch lag screws, they were WAY less expensive than the $35-$40 price at the treehouse supply places.
FarmAndRanchHardware.com in Saugerties, NY - http://www.farmandranchhardware.com/
After doing some digging to make sure this was a legit site (it is) I ordered the wire rope, turnbuckles, shackles, and related accessories from here. The company is actually Fehr Brothers or something, but they sell some stuff through this website. Their prices were considerably less expensive than places like Grainger or McMaster-Carr. UPDATE 6/10/2014 – I got a comment from the company saying the site is now http://endurancehardware.com/.
A Couple Custom Pieces
There is a perfectly good knee brace bracket available online, but something about spending $190 on two of them ($95 each) seemed obnoxious. So like any good engineer, I took to SketchUp to design my own and contacted a local welder/fabricator to make some custom brackets at about half the price. (Thank you, Brandon!)
The design I chose is made from 1/4-inch plate steel and (I’m hoping) should allow for a little easier installation of the knee braces. We’ll see how that turns out… One thing to note – my earlier versions of this design failed to account for water drainage but luckily I wised up and incorporated slots for drainage in the final version. These have been cleaned, primed, and finally painted with a fancy-schmancy galvanized paint to resist corrosion, which was considerably less expensive than powder-coating. I’ll report later on how well this design works out.