How Tree Houses Work

The first step to having your own tree house is choosing a tree or trees (some tree houses span two or three trees). Take a walk around your yard and consider whether you prefer your tree house hidden or visible. How close are your neighbors? Think about who will use the tree house -- adults or kids. Tree houses for kids should be kept close to the ground. The perfect tree for a tree house is not too young, not too old and must be healthy. Apple, oak, ash, fir and beech are some good choices.

When choosing a tree, consider its height and branches in addition to its age and health. Diseased or damaged trees will be unstable -- your house might not last very long and you might not be safe inside it. Trees can be diseased at the root (at ground level or underground), in the trunk or at the core. Other warning signs of an unstable tree are lightning or excessive wind damage.

Additionally, the thickness and angle of the branches makes the difference between a strong or weak support system. Limbs grow naturally in all sorts of sizes, shapes and angles and the strongest limbs are those growing at 90-degree angles. Steer clear of building in elm or sycamore trees -- both of which are prone to disease. Also avoid any tree with a short lifespan, shallow roots or position on a slope.

Trees sway naturally in the wind and so will your tree house. With proper design and construction, the structure will survive high winds. If you live in an area where winds might pose a danger, experts recommend building your tree house in the lower third of the tree, keeping it small to minimize potential damage.

Consider asking a professional for help. Arborists, sometimes known as tree surgeons, specialize in caring for trees and can help you select the perfect one. The arborist will inspect a tree in preparation for construction and give you design and construction advice to minimize tree damage. When built in the right tree and with regular maintenance, tree houses can last an average of 10 to 15 years or longer depending on how long the tree itself lives [source: Tree Top Builders].

Even if you don't have a suitable tree for a tree house, you can still enjoy an above-ground room. Although it's preferable to build tree houses in trees, it is possible to build forts and playhouses on posts in the ground.

Now that we've chosen the perfect tree, let's learn about tree-house design and amenities. Did you know your tree house can have indoor plumbing?

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Just as every tree is different, so is every tree house. Tree house designs are limited by your imagination and the size, shape and species of the tree -- and, sometimes, building codes.

Depending on where you live and what type of tree house you want, you might need permission to build. Restrictions exist that limit height and distance from property lines. Usually permission is needed when your structure will overlook your neighbor's house. Talk to your neighbors as you start the design process. If they know what you're planning, they may be less likely to feel that you're invading their privacy.

If you're not sure what permits you might need or how to comply with building codes, talk to your local planning authorities or a contractor who is familiar with building houses -- they deal with these permits and codes every day.

While traditionally we might think of a dad hammering together a small tree fort over a weekend, it's not uncommon for people to put down their hammers and work with professional tree-house architects, carpenters, arborists and engineers to plan their tree houses. In 2007, professional tree-house builders created an average of five tree houses each month worldwide, ranging from 200 to 2,500 square feet (61 to 762 square meters) [source: Common Ground].

When you're living high above the ground, there's no need to forgo modern living amenities. In today's tree-house designs, plumbing, electricity, cable, heating and air conditioning are all options. Want a fireplace? Add it to the list -- if your budget allows. Tree-house design and building costs have been known to run from hundreds of dollars to hundreds of thousands of dollars, and depends on how much work you do yourself and how luxurious of a tree house you desire.

Having trouble imagining a toilet in a tree? Including plumbing and electricity in your tree house takes some planning -- and you'll need permits since power and water make your tree house more like a regular house. For plumbing, piping is run into your structure from a nearby water source such as a municipal water supply or well. Adding electricity is equally complicated and requires tapping into the power grid and permanently wiring your tree house for power. As in your house, pipes and cables can be concealed cleverly through the design of your tree-house platform and walls. Simpler options, though, include running an extension cord into your tree house or hauling buckets of water. As long as you design and build carefully, any comfort of home can be just as safe as in a ground-level house.

There are also opportunities to go green by using alternative materials in your tree house design. Some people choose solar panels for heat and hot water, and use a waterless composting toilet in place of plumbing. Instead of using pressure treated wood that contains toxic chemicals, some choose reclaimed or salvaged wood and materials for construction.

Next let's learn about tree house construction and safety.

If you don't have the time or the skill to build your own tree house, consider hiring a licensed and bonded contractor to do the work for you. Some are so passionate about building tree houses they will travel to wherever you live to work with you.

If you're a do-it-yourself type tackling the construction of your tree house, stay safe in the off-the-ground work zone by wearing a hard hat, protective goggles and safety harness. Tie your harness and your ladder(s) to a strong tree branch to minimize your chance of falling. Also consider renting scaffolding instead of leaning ladders against the tree trunk. Familiarize yourself with your tools, especially if any are newly purchased for your project. And always keep a first-aid kit nearby.

Are tree houses safe? In a healthy tree with strong building materials, yes. Build tree houses close to the ground, no higher than 10 feet (3 meters) up. Use tall railings and sturdy, well-placed ladders protect children (and adults) from dangerous falls. Consider acrylic plastic sheets in place of glass windows. And avoid splinters by sanding down rough edges.

It's also important to protect the tree during the construction process and beyond. Tree houses do cause mild harm to trees, even when using practices that minimize damage.

Remember that trees are living, gro­wing things. Allow for future growth in your construction plan, and don't cut away branches or pieces of the trunk to make way for your tree house's support system or remove large amounts of bark or wood, which could expose the tree to infection and disease.

Construction techniques also help protect trees from damage. A tree house can be broken down into several parts: the platform, windows and doors, decks and railings, and access.

Building the platform is the first step to assembling your tree house because it is what provides the support system. The platform should be built close to the trunk, with space to accommodate the tree's future growth. It should be level and balanced centrally.

Single, large bolts should be used for main supports rather than nails. Nails are weak, can easily loosen, and because many are needed, it's likely they'll damage the tree. As the tree continues to grow, it will expand over the bolts, in a process called compartmentalization. This creates a tight bond between tree and tree house over time. Another option is Garnier Limbs (GLs), artificial steel limbs created by professional tree-house designer Michael Garnier. GLs are bolted into the tree and are able to support up to 8,000 pounds (3,629 kilograms), significantly increasing the safety of the structure [source: Treehouse Workshop].

Once the platform is complete, it's time to add the floor, walls then roof, which can be preassembled on the ground to reduce the amount of construction done above ground. To ensure your tree house lasts for years and isn't damaged when the tree grows or sways in the wind, be sure no part of your tree house touches the tree; it should all rest on the support system. Windows, doors, decks and other amenities are optional, but railings are a necessity.

But how will you get up there after it's done? Depending on how high you've built your tree house, you may do well with a rope or wooden ladder. For tree houses that are way up high, consider steps -- spiral or straight -- with railings for safety. You can also use a combination of rope walkways and landings or even a pulley system. The possibilities are endless.

For more information about house construction and tree houses, look over the resources on the next page.

Did you know that Roman emperor Caligula had a tree house? Neither did I, and when I discovered that during my tree house research, I was immediately convinced I should book a stay at the Out 'n About Treesort Tree House Hotel in Oregon as a test-run for having a tree house of my very own. Adult-sized tree houses? Sign me up. What was most interesting about the tree house assignment wasn't just the idea of adult-sized tree houses, though. Identifying which tree (or trees) to build a tree house in, from its health to its branches and overall placement always seemed the most important, and most special part, in my tree house-building imagination, but while writing this piece, the construction of the structure is what impressed me the most. Tree houses with fireplaces and running water -- welcome to your treetop house.

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