Redwood Tree House

To design a tree house that will suit Alix's play activities, landscape contractor Alain Joske takes her wish list into account, along with the composition of the tree. The result is a spacious, two-level design that features an overhead canopy, a pulley-anchored basket and a whimsical garden below.

Overall, Joske estimates that this project would take the average homeowner several weekends to complete, and would require about $1,500 worth of materials. (A professional installation would cost around $3,500-$4,000). On a difficulty scale of 1 to 5, with 5 being the most difficult, Joske rates this project a "4," explaining that it requires a thorough working knowledge of tools and carpentry, and presents the added challenge of working in a tree. He also emphasizes the importance of checking out local codes that apply to this type of project before getting started.

To get started, the first consideration is choosing a tree that will provide a sound foundation for the tree house. Joske explains that while it's important to consider the child's requests, it's crucial to make sure the tree has sufficient strength and stability to support the weight of both the structure and its occupants . He also notes that the configuration of the branches is a key consideration, and says that the main crotch of the tree should have an angle that measures close to 45 degrees; angles that are too wide or too narrow won't provide sufficient support. Joske also recommends choosing a mature tree with thick, strong branches and says that the tree house shouldn't be built above the bottom third of the branches; any limbs above this area may be too young to have developed any real strength.

Step One: Building the Frame

Here, Joske has already evaluated the Menudiers' tree and determined that it is structurally sound for a tree house. After designing the two-level structure that will be built into the tree, the next step is to determine the height of the lower level. Once this is decided, the triangular frame is installed. Joske and his crew create the frame with 4" x 4" redwood beams, which are woven through the branches of the tree for extra support.

After the beams are checked for level placement, they are nailed into the tree with rust-proof galvanized nails. Joske recommends using a circular saw (this will generally cost about $10 per day to rent) to cut small wedges of wood that can be fitted between the tree branches and beams to help level them. Special cuts made in the ends of the beams allow them to fit together tightly; Joske advises using a speed square to pre-mark the angles of the ends to make this step easier.

With the beams in place, the next step is to add the floor joists. Here, Joske and his crew cut the joists from 2" x 6"s with two-inch notches cut into the bottom , which enables them to be fitted firmly onto the 2" x 4" support beams. The joists are spaced about two feet apart, toe-nailed to the beams, with the final joist nailed directly to the trunk of the tree as well as onto the frame.

The support frame for the upper level is constructed in the same fashion as the lower level frame, but on a smaller scale; a ten-foot-high, 4" x 4" post that extends from the frame to the ground provides extra support.

Note: While the frame of the tree house featured in this episode utilizes a triangular shape, the form of each tree house frame will be different since it will be dictated by the overall shape of the individual tree.

Step Two: Building the Floors

The floors of the tree house resemble standard decking to a degree, but Joske explains that tree house platforms must be designed with an emphasis on flexibility, since the structures will move with the tree branches when the wind blows.

The flooring is created using more 2" x 6"s, with a 16-penny nail used as a spacer between the boards. These spaces will allow rainwater to pass through the flooring and prevent it from collecting in puddles on the surface.

A reciprocating saw is used to cut the curve of the floorboards that fit around the trunk of the tree, as well as the rounded openings that must be cut to fit around various branches.

Along the edges of the platforms, Joske uses a thin, flexible strip of wood to create a curved arc that he traces around with a pencil. Once the curved lines are drawn, he uses the circular saw to cut along the mark, creating attractive curved edges on each platform.

To add extra support to the lower level platform, Joske secures it with heavy-duty rope that is strung and knotted through the ends of the floor joists and tied tightly to strong branches overhead. (Joske says it's always a good idea to "overdo" supports wherever possible.)

Next, an easy-to-climb ladder is added to the structure, fitted between the two platforms. The ladder is built with 2" x 4"s, with notches in the side braces that allow the rungs to be fitted firmly in place before they are secured with nails.

While the floors are under construction, garden designer Tom Allen sets to work laying out a whimsical garden in the space beneath the tree house. Allen explains that adding a garden to the tree house setting creates a sense of ownership for the child, and also gives them an opportunity to learn about plants and gardening. He also points out that since kids will be playing in the area, the plants must be tough enough to withstand a bit of abuse. (Additionally, Allen recommends choosing relatively inexpensive varieties that will be easy to replace if one is accidentally destroyed.)

In arranging the chosen plants, Allen creates a miniature maze that provides a fun passageway for kids to run through and jump over. He also considers color placement , sun and shade issues and creative options (such as the "miniature doll forest" comprised of rosemary plants). Featured varieties include:

Green Beauty Boxwood (Buxus microphylla japonica), Zones 6-9

Rosemary (Rosmarinus officinalis), Zones 8-10

Primrose (Primula), Dreamer Series, Zones 6-8

Mexican Bush Sage (Salvia leucantha), Zones 10-11

Kid-friendly garden accents include oversized footprint stepping stones, a small birdbath, animal sculptures, a miniature chair and a colorful swing hung from the branches overhead.

Step Three: Building the Railings

For this tree house, landscape contractor Alain Joske has designed a rope railing that features durable, half-inch-thick manila rope, which will be strung through posts that are anchored onto the platforms. (Manila rope is ideal for this project since it won't eventually stretch out as nylon rope would.) Since Alix and her friends are at an age where they know how to practice good safety, these railings will work well. However, in a tree house where younger, smaller children will be playing, Joske says the railings should feature a solid-style wood construction.

The railing posts are cut from 4" x 4"s and the bottom ends are chamfered for a decorative touch. Notches are made in each post to allow them to be fitted securely onto the edges of the platforms. Once positioned, the posts are secured in place with large bolts.

Next, the posts are capped with 2" x 6"s that form the top rail. The boards are mitered at the corners to fit securely together and their width gives them a decorative one-inch overhang on both sides of the posts.

Below the top rail, a 5/8" drill bit is used to bore holes in the posts, spaced four inches apart. (All holes are marked before the drilling begins). Patience is important during this phase... it can be tedious and time-consuming! Once the holes are finished, the half-inch-thick manila rope is threaded through the posts in one continuous piece to span the front of the platforms in a total of six rows.

Finally, Joske suspends a pulley from an overhead branch (slightly in front of the lower level), and fits it with a length of rope that is tied to a basket below . The basket will allow Alix to bring up toys and snacks without carrying them as she's climbing up the ladder.

Step Four: Project Review & Final Touches

With the railings complete and all accents in place, the tree house is ready for its new owner. Final touches include flower-filled window boxes anchored along the railings, a tarp canopy secured above the upper level for shade and a birdhouse hung from the platform of the lower level. Once the crew is finished, Alix wastes no time in making herself at home in her wonderful new backyard refuge!