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A place of your own: grown-up treehouses

  • 10/25/2016 3:48:00 PM
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By Mindy Kralicek
From the September/October 2014 issue of Iowa Outdoors magazine
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You don't have to be a kid to have a treehouse! Know what to consider to protect the health and safety of your trees and hideout | Iowa Outdoors magazineIf you weren’t lucky enough to have a place of your own in a tree or other hideaway as a child, it’s a good bet you wished you had one. 

A private place surrounded by nature is soothing to the soul, and up in the trees is first rate. And, you don’t have to be a child to want a place of your own.

Lynette Rasmussen, an attorney living in Polk County, likes to read and watch squirrels and birds that nest in the trees surrounding her family’s treehouse. “It’s a great place to go and talk with someone important to you without the distraction of electronics,” she says. 

Her children have their friends up in the treehouse, enjoying the outdoors together. Her youngest daughter spends a lot of time in the play structure underneath, jumping from rock to rock, in a swing hanging from one of the beams and loafing in the rope-baggage-style hammock.

For Jacob Mueller, it was a house built on posts 14 years ago by his grandfather especially for him, his brother and his cousin. It was tucked into the evergreen windbreak on his grandfather’s farm in Jones County.

“My grandfather knew we loved the outdoors and climbing trees and he did something about that. He built this house for us in the trees. It touches my heart when I think about that. We played in it a lot. It was where our adventures began,” says Mueller.

Brent Nie, an architect, built a half-dozen structures in trees as a kid. “I’d see a tree that would start me thinking about different ways to build a tree fort and then I’d build it. It was a compulsion.”

As a college student at Iowa State University, Nie designed and built a treehouse for a class with the goal of not impacting the chosen tree.

“The treehouse is in a huge oak overlooking a pond on my uncle’s land in Greene County, a very peaceful place,” says Nie. “A few feet from the oak trunk is a red cedar—a natural ladder to climb to the lowest platform in the oak. My class project partner and I climbed up and down those cedar branches hundreds of times during construction. Even in my sleep I climbed those branches. Although I didn’t get to use the treehouse myself, I built it thinking someday another kid will discover it and explore the tree.”

Tree stressors
Rick Tagtow, executive director of the Midwestern Chapter of the International Society of Arboriculture and a consultant in arboriculture and urban forestry, is not supportive of attaching structures to live trees, although he understands the attraction.

“As an arborist, I see trees under a lot of stress, especially in urban areas. Away from their natural environment—the forest—they are placed where the soil is probably compacted from construction equipment.  They have to compete for water with thick grass lawns and a flower bed planted over their root system. They may be sprayed by passing vehicles with chemicals used to melt ice. If planted under or near electrical and telephone lines, trees may get topped or major branches chopped off. They are exposed to various air pollutants. A driveway may cover part of their root system.

“Trees are often treated as if they are short-term plants; yet the value of a tree improves as it grows older,” advocates Tagtow. ”A tree that’s 100 years old and properly cared for provides a lot of benefits—especially in cities where they contribute to cooling in the summer, protect animals and people from rain and wind, provide food and shelter for wildlife and are beautiful to look at.”

If you’re close to making a decision to build a treehouse, here are some important considerations.

You don't have to be a kid to have a treehouse! Know what to consider to protect the health and safety of your trees and hideout | Iowa Outdoors magazineAsk Yourself A Lot Of Questions
If you intend to build a treehouse in the city, first make sure there are no ordinances or building codes pertaining to building treehouses. You may be required to obtain a building permit, although Mark Tomb, director of membership services for the Iowa League of Cities, is not aware of specific cities that have had this concern.

“However, if the place you plan to build a treehouse could impact your neighbors’ view, privacy or fencing, talk it over with them before you begin,” advises Tomb. “They may be just as excited about it as you are and offer to help; or they may be completely put off by the idea, in which case it is good that you asked before causing tension with your neighbors.”

Decide what the treehouse will be used for, how often, how long and by whom. How much weight will it need to support? An average 8-foot by 8-foot treehouse will need to be supported by a hardwood tree that has a trunk diameter of 12 inches or more.

What special features do you want? A roof, walkway, bridge, swing or climbing rope? What safety and security provisions should be made? You may want the treehouse away from public view to reduce the temptation for others to vandalize or be in the treehouse without permission.

Best Trees For Supporting Treehouses
What tree species support a treehouse best? In Iowa, the recommended trees are maple (sugar or red), hickory, black cherry, oak, eastern red cedar and apple.

You may have problems with ash or elm (diseases and insects will impact its strength), black walnut or sycamore (brittle branches), cottonwood (weak-wooded), birch (short life span and weak branches) or poplar and aspen (shallow roots). 

Is the tree healthy with a strong root system and shaped so that a treehouse is feasible? Trees should have a healthy canopy, leaves that are green and supple and a root crown that resembles the end of a trumpet. Inspect selected trees for wood-eating insects and signs of disease. Be sure the trunk has not been damaged by lawn mowers and weed-whackers. Such injury could weaken or kill the tree eventually.

The soil underneath the tree canopy should not be compacted. Soil compaction and trenching, digging or adding fill dirt within tree root zones often cause future tree health problems and weaken the root system. Another consideration is strong winds. A tree in a forest will experience less wind than a tree out in the open. 

Tree root systems
Tagtow points out the fallacy of thinking tree roots are as deep as the tree is high. “The depth of most tree roots is less than 12 inches in the soil. The vast majority of fibrous roots that take up water and nutrients into the tree are in the top six inches of soil.

“Another fallacy is that tree roots go out to the tree’s drip line. That’s not true either. Many tree species grow roots laterally much farther than the height of the tree.” 

There is no particular regular branching pattern for roots like there is for branches and leaves above ground. Lateral roots arise from tissue on the outside of larger roots. The root cap protects each root tip as it is forced through the soil. Right behind the root tip are root hairs which are fine outgrowths of single cells where water and nutrients are absorbed. Root hairs live for a few weeks and then are cast off. 
Removing fine roots here and there will probably not cause the tree a problem, but don’t hack through major roots an inch thick or thicker in order to place treehouse support posts. That is likely to weaken the tree.

The tree should dictate the plan
Consider various structure options for the treehouse. Two, three or even four trees may be used to support a treehouse and distribute the weight load. The house could be supported by posts in the ground and a tree, or by posts alone. The strongest branches on a tree grow at about a 90-degree angle to the trunk, if you plan to have more than one level for your treehouse. 

When you have made some decisions, it’s time to sketch out ideas and plan the size, materials, hardware and tools you’ll need. Although there are plenty of plans in books and on the Internet, the plan should be designed for the tree. Don’t try to make your tree fit a chosen design.

Bring in an arborist
The planning stage is a good time to bring in an arborist. An arborist can help determine if the tree selected is healthy and strong enough to support a treehouse and help with pruning decisions to open up the tree for construction to minimize health impacts. He or she may suggest plan changes to make your treehouse safer, or if you need posts to support the treehouse, an arborist can tell you where to place those to minimize damage to the tree’s roots. They have the safety equipment and skills to perform tree pruning as well.

If you will use one tree with multiple trunks, the arborist may suggest tying the trunks together with cabling above your treehouse. Follow the arborist’s instructions, as they are trained in this kind of work.

Before construction begins
Estimate the cost. You may find you need to adjust the plan to fit the treehouse budget.

Remove dead wood and snags from the branches and prune the tree. Clear debris and vegetation away from the tree’s root system—as far out as the tree’s branches. This helps the roots breathe and prevents competition for nutrients and water.

Spread a couple of inches of compost or deciduous mulch if it’s a deciduous tree, or cedar mulch if it’s under a cedar tree.

If your treehouse will be large or will block rain from reaching the tree’s roots, buy a soaker hose to use occasionally below the tree. Do not irrigate the tree trunk directly.

Do all the work on the treehouse that you can on the ground. It’s a whole lot easier to do it there than in a tree.

Rasmussen Treehouse
When the Rasmussen children outgrew their playset in the backyard, parents Kurt and Lynette began contemplating how they could enjoy the backyard more themselves, along with their teenagers, preteen and friends. The family was big on camping and exploring the outdoors, making their own fun and respecting and appreciating nature. Both adults had treehouses as children, and expressed their common dream of a treehouse like the one in the Disney film, Swiss Family Robinson.

They contacted Silent Rivers architects and designers and shared their desires. 

“They took our ideas and came back with great spaces for us to entertain and enjoy peaceful relaxation. There is a swinging bridge and a rope bridge, playscape underneath, a hatch entry to one of the levels, plus they added several details in the design that personalized the structure just for us,” says Kurt. 

Designer Tyson Leyendecker explains his design process and minimizing the impact on trees.

“It wasn’t a linear process. The area had a large elm tree, and Kentucky coffeetrees where we were to build the treehouse. There was Dutch elm disease in the neighborhood, so we had the elm treated. The arborist with Wright Tree Service guided the pruning before construction began. They also reinforced weak crotches in the elm and coffeetrees. We decided to build a two-tiered, freestanding platform as the strength of the elm was too questionable.

“There are two other platforms attached to coffee trees: one tree has a platform attached to it by a custom-made bracket that allows for a small amount of movement. The other is attached to a tree with a beam and supported by two additional wooden posts that angle together at the ground. Four braces help strengthen the beam attachment to the tree.”

The playscape is shallowly mulched with pea gravel that allows rain to soak through to the tree roots. Additional trees were planted near the structures to get some height before the elm tree succumbs to the inevitable.

Mueller’s Post House
Working from a mental plan, 70-year-old Dale Mueller built an 8-foot by 6-foot house from tubular steel, insulated it and paneled the inside for his three grandsons. It features a front porch, recycled sliding plastic windows and a spring-closure door. At the beginning he intended to move it to his son’s place in Des Moines for placement in a cottonwood tree, but it became bigger and heavier (600 pounds) as it was completed, so instead Mueller and his son Marlon used a skid-loader to place it onto four 8-foot treated posts in 3.5-foot holes dug below the frost line. Using brown colored steel siding, the house blends into the windbreak of evergreen trees at the family farm near Monticello.

“My brother and I went crazy when we saw it,” says Jacob Mueller, an 8-year-old at the time with a 6-year-old brother, Andrew. “We’d spend all day in and out of that house, even eating lunch in it. It was our own house up in the trees.”

Cousin Josh Pierce lived a mile from his grandfather and helped build the metal house. 

“My grandfather taught me welding and metal work on that treehouse (Pierce was also 8 at the time). It was a giant structure to me. When he decided it was to go in the windbreak, he welded caps on the bottom of the structure to place over the posts my uncle put in.

“The inside was 5 feet high,” continues Pierce. “I was the tallest, so it was only a few months before I had to duck to get around in it, but that was part of the experience. When we were up in the house, we were in the ‘timber.’ We played cowboys and Indians, riding horses through the forests and mountains in our collective imaginations.

“Now I’m in my senior year at the University of Wyoming, majoring in ag business. In the summer of 2011, I had the chance to work for a Yukon outfitter (in Canada) as a hunting assistant and guide. The place was a hundred miles from a paved road, so we drove the horses over the mountain terrain to the lodge on horseback. I had a lariat and gun packed alongside my saddle and was riding across some rough land. We swam across rivers hanging onto the saddle horns of our horses. I got a chance to live those imagined adventures we had as kids. 

“I can still picture that metal treehouse. It was a place that set our imaginations free.”

Nie’s cabled treehouse
It’s probably a quarter-mile walk from the county road and there’s no farmhouse on Brent Nie’s uncle’s land. Gigantic trees surround a pond. Nested in a giant oak is Nie’s concept of what a treehouse should be: a structure that incorporates the existing circulation and qualities of a tree that make a person want to be in a tree.

“It seems people want to be in a tree, but they don’t know how,” says Nie. “They know how to be on the ground, so they construct a house in a tree that is like a house on the ground. Once they enter that type of treehouse, they might as well forget they are in a tree. 

“I wanted to design something that uses architecture to reinforce the qualities of climbing and inhabiting a tree. I wanted a treehouse that behaved and could be experienced as part of the tree.”

We step on the spacious treehouse platform after climbing the limbs of the cedar tree. A breeze filters through our hair and gently stirs the oak leaves. “This really is peaceful,” says Nie softly, as his gaze follows a cable structure through the branches and out to the wooded hillside beyond.

“It’s interesting to be back after four years to see how my ideas worked out. My project partner and I cut cedar planks for the floor. Cedar contains natural protective oils so the wood doesn’t require a preservative. The wood was bright purple-red when we installed it. The spaces between the boards allow rain, leaves and twigs to fall through to the ground, and it is a constant reminder that we are off the ground and in a space unlike any other. The wood has weathered to blend with the bark of the tree. So have the bolt heads. I didn’t want shiny bolts, so I avoided using galvanized bolts where they weren’t needed.

“The weathered wood blends in with its surroundings, yet still stands out—like an old weathered hay wagon sitting in a fence row. It just looks like it belongs there.

“I didn’t want to put any holes in the tree so we used a cable system over branches to support the floors. A problem was how to keep the cable from biting into the bark of the branches. We decided to keep the cable between blocks of wood to serve as buffers. We figured wood against wood would be less destructive, and it looks like that has worked out in these four years. I can see the cables need some adjusting. 

“We left space for a dead limb to come through the floor. We decided to leave it so it could be used as a seat. Now, I’m afraid the limb might break and damage the structure.

“There’s another small platform about 8 feet higher above our heads,” points out Nie. “I wanted a higher structure to encourage a person to climb higher and prolong the experience.”

Another feature of Nie’s treehouse is that it was built to be adjusted as the tree grows, by removing sections.

The tree experience
Whether it nurtures imaginations, builds skills and confidence, opens minds to experiencing nature, teaches biology and physics or provides a place to share time with someone important to you, a place of your own in the outdoors is an important experience at any age. 

If you build a treehouse, build with regard to the tree’s nutrient and water circulatory system, growth 
and movement in wind. A tree cared for properly is a testimony to the enduring qualities of nature and 
a symbol of hope for the future.