We’ve finished the walls and windows.  Now it’s time for the ‘woof’.  This structure presents the same challenges as the floors: it’s got to grow with the tree.  However, unlike the floors, which I was able to stand on to build, I needed to make the roof a light-weight structure, which I could erect “from below”, because it is so high off the ground.

My solution was simple… in concept.  Use heavy duty polyethylene clear plastic sheeting as the roof surface stretched between supporting rafters.  Think of it as a giant umbrella.  The plastic makes the surface flexible to accommodate tree growth over the years.  Its light weight makes it easy to install “from below”.  Its low cost makes it affordable to experiment with. 

I started by making the rafters of 2×3 oak boards.  I built one for each of the five corners of the structure with another to raise a gable over the block-and-tackle hoist arm.   Once these were fastened to the tree trunk it was time to stretch the plastic between them.  Having stumbled around the second floor using a wobbly 8 foot step ladder to erect the rafters we decided it would be much better to build a scaffold to install the plastic sheeting. 

Jonathan, Dan and I lowering the no-longer-needed-ladder.

I mentioned above that the plastic idea was “simple…in concept.”  Well, after a couple false starts with plastic, experimenting with different ways of arranging it on the gables, we figured out the approach that would work best…or at least easiest.  We measured and cut five triangular segments for each side of the pentagon. 

These were overlapped, tightened and secured to the rafters…often dangling out over 30 feet of air.

Dan and I secure the final bit of plastic

Roof viewed from down below.

Nice view of rafters, hoist arm and plastic sheeting pulled nice and tight.  You like?  Since the roof system is experimental I’ll be very attentive to see how it “weathers” this winter, bearing up under the stresses of wind and snow when there is no leaf cover to protect it. 

The Treehouse is now “structurally complete”.  All the systems are in place from my original drawing.  There are still several things that need to be completed: 

• Build and install hatch doors for the first and second floors.  With those in place we’ll be able to decide on floor coverings to weather proof the interior above and below.
• Craft my escutcheons.  Wondering what an ‘escutcheon’ is?  It’s defined as “a decorative plate that surrounds a faucet in a bathtub or shower”.  In the case of my escutcheons, they surround an 88 inch tree trunk inconveniently located in the center of my floors.   
• I’m eager to get rid of the makeshift railings on the second floor and install the final system, which I’m thinking will be heavy duty netting. 
• I need to decide on the means of egress from the ground to the first floor, either a ladder semi-permanently installed or a retractable stair similar to the staircase to the second floor. 
• I’ve got to trim and furnish the interior and the deck.  I’m also still mulling my options for lighting and heat, whether to go with propane (cheaper) or generated electricity (safer).

I’ll issue a final post with lots of pictures in the spring when all the work is done.

This has been quite the building adventure and I’m grateful for its near-conclusion.  I couldn’t have done this without my wife’s vision and encouragement, without “a little help from my friends” particularly Dan and Jonathan LaPre, Mike and Mike at Volpone Home Improvements, Danny Thomas, Jon Coate and Eamon Coy and the helpful guys at Loudoun Lumber.  The generous people of St Peter’s Episcopal Church in Purcellville gave me the time off from being their pastor and supported me financially to make this project possible.  Thank you ALL! 

In my line of work I don’t get to see a lot of tangible results of my labor.  Rarely do I get to see an idea go from dream to plan to execution to conclusion.  This Treehouse has given me that gift.  It actually came out BETTER than I envisioned!  How unusual…

I guess you can say I’m one satisfied builder…

GOT WOOD?

We had to relieve the monotony of the pentacube.  Time for wallpaper, windows and battens.

First I cut window-shaped holes in the walls and installed windows, one for each wall except the wall with the stairway.  I was able to acquire nice, durable windows of the right color, size and price by searching online for play-house windows.  After installing the windows we framed them and hung the battens to cover the seams between the boards. 

This was the most precarious work we did on the tree house.  It required working perched 16+ feet up a ladder mounted on often-uneven ground at a sharp angle against the outside of the structure.  Once up there you’re slinging a heavy 18 volt screw gun, over your head, at full arm’s length driving 3 inch long screws at an awkward angle.  It’s very challenging for guys who don’t do this for a living.   My friend Dan LaPre was a true champ putting himself up the ladder every day for nearly a week to get the job done. 

Nailgun also helps get the job done.

The results speak for themselves.

For wallpaper we selected something special: wall covering called Tyvek from the Laura Ashley Collection line carried by Loudoun Lumber.  Tyvek is a super durable, weather resistant, breathable house wrapping product.  We hung it on the inside of the walls to make them impervious to wind and moisture from the outside, and yet permeable to moisture and air from the inside.  Nice. 

It’s all part of making this a four season luxury deer stand and camping cabin.  A nice side benefit: the white Tyvek brightens the interior.  I’m hunting now for an appropriate covering for the floors to complete the effect. 

The poplar ‘pentacube’ becomes a true Treehouse…a veritable cabin in the air.   

But without a roof it’s really not very useful…

Next up: the Twelve Foot Umbrella.

Now it’s time to put some weight up the tree.  It’ time to nail up 300 board feet of poplar for walls.  These walls will be of board-and-batten construction, secured to the floating floors.  The boards (generally 12 inch wide) are butted up vertically to each other.  The battens (3 inch wide strips) cover the seams between the boards.  The boards can shrink and expand with the weather (about ¼ inch per foot of board width) and the battens keep the weather out. 

Let's start moving the boards up the tree.

Keep 'em coming!

After a couple of sessions we got all the boards up and now the tree house looks like a giant pentagonal box in the sky. 

Up next: wallpaper, windows and battens to break up the monotonous board-om of the penta-cube.

The time has come to connect the first floor to the second with stairs. Our trusty 2×6 oak boards did the trick beautifully. We made a sturdy and attractive stairway with about 12 inches of rise for every 6 inch stair tread. The dimensions remind me of stairs in Navy ships.

I installed a block-and-tackle hoist arm to lift the heavy stair (and other weighty matters) up the tree. This is a “double tackle” with the rope pulling through the sheaves four times. This gives a mechanical advantage of 4 meaning it takes only 25 lb of force to move a 100 lb load. See http://en.wikipedia.org/wiki/Block_and_tackle for more details.

With some final fitting, the floor is ready to be “boarded”.

C’mon up!

A nice shot from behind. See the stairs and the struts…and the pile of poplar boards awaiting Phase Four: Walls.

Upon a return from Massachusetts work commenced again.  Time to build the second floor.

This time we got to cut our own lumber: 2×4 and 2×6 oak and…

… 1×12 poplar for the second floor walls.

The key to the second floor is the 12 foot long 4×4 pillars running up from the first floor corner supports to hold up the second floor corners. 

To make a strong joint between the supports and the pillars I cut mortises into the pillars.  A “mortise” is a big square or rectangular hole into which a board fits.  It makes a very sturdy and attractive joint for pieces of wood joined at right angles.

Posts are in place and the corner supports for the second floor.

With the supports in place we made the second floor with oak boards, a mirror image of the first floor, and built a makeshift railing around the upper deck. 

With the second floor in place we cut the boards for the first floor walls.  We used a Poplar tree because its wood is light and abundant.  It guess that’s why it’s ‘popular’.  Light as those boards are, however I realized that walls would add a ton (almost literally) of weight to the structure. 

We needed to beef up those struts.  Thankfully that was easily accomplished by adding two oak 1×6 boards to each of the 2×6 struts supporting the floor.  We were also able to further bolster the corner struts by adding 4×6 tie-ins. 

A view from the second floor… 26 feet above 

Next: stairs

My original plan was to harvest and cut all the lumber on the farm, which has a portable band-saw saw mill to make fence boards (lots of four-board fencing on the farm). Unfortunately the farm was extremely busy in May with restoring the gravel driveway after a couple damaging washout rains and cutting hay. Lumber wasn’t on the agenda. So I bought my first batch of lumber to build the main supports and pillars. We made the floor from oak boards we had already cut earlier in the year.

Phase One:

I fabricated the main supports in my shop at home and with help from Mike and Mike (the fun-loving raconteurs of woodwork of Volpone Home Improvements) we installed them on the tree. The farm manager was generous with his time to lift us up to that height in the tractor bucket.

Day 1: we installed the corner supports with massive effort and ingenuity to shim them plumb and level on a leaning tree.

Day 2: since we had the “hang” of it installing the floor supports was much easier. Being fully supported we proceeded to put the oak floor in.

Labor all-told: 12+ hours each of highly skilled labor from Mike and Mike, 12 hours of semi-skilled assistance and direction from me, with indefatigable support from our young helper Henry.

Just finished flooring: Henry, Tom, Mike

Oooh, that's nice!

With makeshift railing he won’t fall off.

It’s UP there!

It’s over there…with our bovine observers

It’s down there in the holler.

We got this far in time for me to trek up to Gordon-Conwell Theological Seminary for my two week Doctoral residency in June. To be continued with Phase Two…

It took a couple of weeks (and the generous input of several friends far more competent than I) to work through the engineering challenges of bearing all that weight, and moving with the growth of the tree.

Weight – Oak floors and board-and-batten walls weigh a lot. And with 140 square feet of “living area” you can entertain a lot of people up that tree. How to support it all?

My original plan used 2×6 struts but Mike Volpone suggested I’d be better off with beefy 4×6 to bear the weight compression of both floors and the walls (and whoever is occupying them). We added scrap 4×6 material as cross-ties to further support the struts.

Growth – Trees grow, right? I had to create a structure that would grow with the tree for years to come. A poplar adds 1 ring a year of approximately 1/8 inch in width. That means I had to anticipate the tree gaining 1 inch in diameter every four years. So anything attached to the tree is moving outward at that rate. So anything attached to my main supports is also pulling apart as the supports move outward. Ancient Chinese proverb say, “wrestle not with a growing tree.” How to work WITH the tree rather than against it?

After considering a few options a simple idea came to me: float the floor. Let the tree grow. Let the supports move. Let the floor rest upon the supports, but don’t fasten the floor to the supports. Float the floor.

The first floor walls can be fastened to the floor and ceiling and be part of the floating system, while the floor supports are part of the growing tree system.

With these challenges addressed we began construction in early May. That’s where things get REALLY interesting.

The Design

The design was elegant: five main supports radiating outward from the tree trunk to the corners of the pentagon. Each corner would end with a post which bears the weight of the second floor.

For the length of these corner supports I picked a nice round number: 5 feet. I figured that would be a manageable dimension and give us plenty of elbow room inside the structure.

I then made a back yard mock-up of the floor plan in actual dimensions-

Analyzing my floor plan in the grass I discovered that with 5 ft Corner supports, the side supports would be 4 ft long and each of the sides would be approximately 7 feet long. That turned out nicely. I was immensely pleased to stumble upon such simplicity.

Walking around my floor plan in the grass I discovered… The scale was massive. It is two floors of nearly 84 sq feet each (subtract 5 sq feet for the area of the tree trunk), the lower enclosed with walls and windows, the upper deck bound with a railing.

This design confronted us with two engineering challenges: dealing with weight and growth.

The idea was born a few years ago when my family and I visited a house for sale. In back was an incredible, custom-made play house on stilts. After our kids climbed all over it like squirrels, my wife suggested I build something like it for them. The dream was born. I made measurements on site and sketched out the design…and forgot about it. Too busy.

Then as I was imagining my sabbatical leave in Spring of 2010, the tree house idea emerged from oblivion – again at my wife’s suggestion. I began looking for design ideas to supplement what we had seen on the real estate tour. I considered several. During the winter I settled on what we have built this summer: a pentagon shaped structure built around a tall, straight, sturdy tree.

I wanted to build something that would be large and beautiful, lots of fun and adventure for kids (even as they get older), useful for adults as a luxury deer stand and camping cabin, and durable enough to last for grandchildren 30 years from now.

Here’s the first picture I drew of the Treehouse. You can see the roof, the second floor railing, the first floor walls with windows, and the struts that support the weight.

I’m a builder.  It’s just the way I’m wired.  Since childhood I’ve loved making things large and small, from dams in the creek to forts in a tree.  My priestly work at St Peter’s in the last several years has been “building” the people, groups, organization, and ministry of our church.  Our growth in numbers, capacity, and spiritual maturity has been exciting.  But all the while I’ve yearned to build in more “concrete” ways: designing and building a large-scale construction project. 

I used to build houses on framing crews during the summers in high-school and college and I had a small cabinet-making business “on the side” in the early 2000s.  But as my family and congregation have doubled in size, being “father” to both has absorbed my time and creative energy for making things. My sabbatical leave (May 1 – August 15 of this year) has been the perfect time to recover my avocation as a wood-worker and carpenter…to build the Ultimate Treehouse. 

In the entries that follow I’ll tell you how it’s all come together.