Tree House Plan

Brian Barth
tree house

Building a tree house is every child's dream, but an adult is needed to make it a reality. If you're going to indulge your kids and erect the ultimate play fort in the backyard, try a simple, worry-free method.

Tree Houses Simplified

The daunting part about building a tree house is attaching it, safely, to a tree. To do that right -- in a way that won't hurt the tree and won't cause the tree house to fall apart in a few years -- takes an advanced degree in engineering. However, an easier approach it to build the tree house around the tree. That way, when the trunk sways in the wind and the limbs grow and twist over time, the tree house (and your kids inside it) will be safe.

Things to Keep in Mind

Safety is number one when building a tree house, so make sure to follow these basic principles:

  • The higher the tree house is off the ground the more precautions you should take to keep people from falling out of it - e.g., railings.
  • Trees can move significantly in the wind. Make the opening around any trunk or limb at least twice the diameter of the trunk or limb.
  • Check with your home insurance company to see if accidents arising from a tree house are covered.
  • Make sure the tree itself is structurally sound -- if in doubt ask an arborist to verify that there are no weak branches or internal rot that could cause it to come down in the foreseeable future.

There are various legalities and neighborly relations to consider, as well:

  • Check with your local municipality to find out about building codes related to tree houses. For example, some areas may require deeper post holes to account for frost.
  • If the tree house will be highly visible to your neighbors or near a property line, make sure you have their blessings before moving forward.

Project Materials

A 5 pound box of 3-inch exterior wood screws, a 5 pound of 2-inch exterior wood screws, and a 1 pound box of 1-1/4-inch exterior wood screws should be sufficient for the project. One pound of 1" self-tapping sheet metal screws with rubber washers and a dozen or so 1-inch galvanized nails will also be needed.

Deck Frame

  • 4 - 4"x4"x12' pressure treated posts
  • 16 - 60 pound bags of concrete
  • 4 - 2"x8"x8' pressure treated joists
  • 16 - 1/2''x6" galvanized bolts with lock washers and nuts
  • 2 - 2"x4"x8' pressure treated boards

Joists and Flooring

  • 6 - 2"x6"x8' pressure treated joists
  • 10 - joist hangers
  • 16 - 5/4"x6"x8' pressure treated deck boards

Stairs

  • 2 - 2"x8"x6' pressure treated boards
  • 1 - 2"x6"x8' pressure treated boards

Roof Support

  • 2 - 2"x4"x8' pressure treated boards
  • 1 - 4"x4"x8' pressure treated beam
  • 2 - 16-inch nail straps
  • 4 - 2"x4"x8' pressure treated boards
  • 5 - 2"x4"x12' pressure treated boards
  • 10 - rafter hangers
  • 10- hurricane ties

Roofing

  • 4 - 12' sheets of corrugated metal roofing
  • 1 - 8-foot metal ridge cap

Front Wall Frame

  • 4 - 2"x4"x6' pressure treated boards
  • 1 - 2"x4"x8' pressure treated boards

Door Frame

  • 1 - 2"x2"x14' pressure treated board
  • 4 - galvanized hinges

Window and Balcony Frame

  • 2 - 2"x4"x8' pressure treated boards
  • 1 - wood sash window

Siding and Hardware

  • 25 - 1"x12"x8' pressure treated boards
  • 2 - galvanized metal handles
  • 2 - galvanized metal hasps

Tools

  • Circular saw
  • Ratchet and socket set
  • 4-foot level
  • Electric drill
  • Hammer
  • Tin snips
  • Tape measure

Step-by-Step Instructions

This tree house plan does not require attaching the structure directly to the tree, allowing it to be adapted a wide range of situations. It is similar to constructing a shed except it is elevated off the ground and has a hole in the roof and floor to allow the trunk to pass through.

Click on the images for printable plans based on the instructions below. If you have trouble downloading the plans, use the Guide for Adobe Printables article to troubleshoot.

Deck Frame

Rather than a typical shed floor, this design uses a floor similar to a deck since the structure needs to be weatherproof inside and out -- there is no way to seal out moisture with a hole in the ceiling for the tree trunk. The deck is accessed by a ladder-like set of stairs.

  1. Set four 4"x4" posts in concrete to make the four corners of an 8 by 8 foot square. Use four 60-lb bags of concrete per post, setting each one 2 feet below grade.
  2. Install 2"x8" boards to the outside of the four posts using two 1/2''x6" galvanized bolts with lock washers on each end of the boards. Install them so they are level with the top surfaces of each forming a horizontal square 5 feet off the ground.
  3. Cut two 2"x4" into eight 2-foot pieces. Cut a 45 degree angle into each end of the pieces and screw these between the posts and the joists as braces using 3-inch screws (the cuts should be in opposite directions so the board ends up with a trapezoid shape).

Joists and Flooring

Install all 2"x6" joists so they are one inch below the top of the 2"x8"x8' frame.

  1. Install 2"x6" joists every 24 inches between the 2"x8"s using joist hangers and 1-1/4-inch screws.
  2. Install a 2"x6" joist directly to the inside of the front and back 2x8"s.
  3. Install one more 2"x6" joist three feet from the front of the structure. This joist will support the studs for the front wall of the tree house.
  4. Screw 5/4"x6" deck boards on top of the joists with an 1/8-inch gap between each one using 2-inch screws. Cut the deck boards as needed to allow space for the tree trunk to pass through.

Stairs

  1. Cut a 22.5 degree angle into the ends of a 2"x8" pressure treated board to form sides for the stairs. The cuts should be in opposite directions so the board ends up with a trapezoid shape.
  2. Screw the end of each board two feet apart to one of the 2"x8"s next to the corner where you want the entrance using 3-inch screws. The other end will rest flat on the ground.
  3. Cut a 2"x6" into four 2-foot pieces and screw these between the side boards of the stairs as steps. Space the steps every 12 inches and make sure they are level.

Roof Support

The tree house has a simple pitched roof supported by the four corner posts that are already in place and two 2'x4" posts that will be installed to support the peak of the roof. The rafters will rest on a horizontal square of 2"x4"s mounted to the top of the existing corner posts.

  1. For the central roof posts, screw a 2"x4"x8' flat to the midpoint of the 2"x8" joist on the side where the entrance to the tree house will be with 3-inch screws; this will involve cutting a notch in the decking to allow the 2"x4" to pass though. Mount it so the top of the 2"x4" extends 80 inches above the decking and repeat the process to install another 2"x4" on the opposite side of the decking.
  2. Cut off the bottoms of the 2"x4"s so they are flush with the bottom of the 2"x8" joists.
  3. Rest a 4"x4" beam across the top of the 2"x4" posts and secure them with nail straps and 1-inch nails.
  4. Screw four 2"x4"x8's to the tops of the four 4"x4" posts, forming a horizontal square around them, with 3-inch screws. Screw these four 2"x4"s into the 2"x4" roof posts at the point where they cross using 3-inch screws.
  5. Cut five 2"x4"x12's in half using a 22.5 degree cut at the midpoint of each. Install these as rafters every 24 inches along either side of the 4"x4" beam.
  6. Connect the rafters to the beam with rafter hangers using 1-1/4-inch screws.
  7. Connect the rafters to the horizontal square of 2"x4"s with hurricane ties using 1-1/4" screws. The rafters will extend about 16 inches beyond the horizontal 2"x4"s.

Roofing

  1. Cut four sheets of corrugated roofing in half with tin snips and screw the pieces to the tops of the rafters with 1-inch self-tapping screws.
  2. Cut a hole in the roofing material where needed to allow the trunk to pass through.
  3. Screw a metal ridge cap into place to cover the peak of the roof using the same screws.

Front Wall Frame

Four 2"x4" studs must be installed to frame the front wall of the tree house where the window and door will be located -- these will be mounted to the extra floor joist that was installed 3 feet back from the front of the structure. A couple of horizontal 2"x4"s also need to be installed to support the siding on the front of the balcony, but the roof supports will suffice as framing for the siding on the other walls of the structure.

  1. Screw a 2"x4"x6' flat to the 2"x8" joist on the side with the stairs 3 feet back from the front corner of the deck using 3-inch screws; this will involve cutting a notch in the decking to allow the 2"x4" to pass though. Mount it so the top of the 2"x4" is flush with the top of the horizontal square of 2"x4"s (a height of 5 feet above the deck). Repeat the process to install another 2"x4"x6' on the opposite side of the decking in the same location.
  2. Screw a third 2"x4"x6' to the extra 2"x6" joist (the one that is 3 feet back from the front of the structure) at the midpoint between the 2"x4"s that were just installed so that it also extends five feet above the deck. Screw a fourth 2"x4"x6' midway between the first and third 2"x4"s in the same fashion, resulting in two 2-foot openings and one 4-foot opening.
  3. Cut off the bottoms of the 2"x4"s so they are flush with the bottoms of the joists.
  4. Rest a 2"x4"x8' across the top of the four studs as a top plate and screw it into them using 3-inch screws.

Door Frame

  1. Cut a 2"x2"x14' board into two 2-foot pieces and two 5-foot pieces.
  2. Screw these together to form a 2 by 5 foot rectangle using 3-inch screws. This will serve as the door frame -- mount it to the 2"x4" stud in the center of the front wall of the tree house using a pair of galvanized hinges.

Window and Balcony Frame

  1. Cut two 2"x4"x8' boards in half to create four 4-foot boards.
  2. Mount two of the 4-foot boards horizontally between the 2"x4"s to the right of the door frame using 3-inch screws -- one at 3 feet above the deck and one at 4 feet.
  3. Hang a window from the top 2"x4" using a pair of galvanized hinges. The height of the lower 2"x4" can be adjusted as needed depending on the size of the window you will use.
  4. Mount the other two 4-foot boards horizontally between the front 4"x4" posts and the 2"x4" post between them at a height of 3 feet using 3-inch screws to support the siding at the fromt of balcony.

Siding and Hardware

  1. Use 2-inch screws to mount the 1"x12" boards to the exterior of the framing to serve as siding for the structure. The 8-foot boards can be used whole on the front of the balcony and the right and back walls of the structure. The boards will need to be cut down to various lengths for the remaining areas: 5-foot boards for the left wall and the portions of the wall above the windows; 5-foot boards for the door (mount these vertically); 2-foot boards for the wall to the left of the structure.
  2. Install a galvanized metal hasp and handle on the door and window.

Tips and Variations

This is a very simple tree house design that can be customized in many different ways.

  • Put the stairs under the floor rather than on the side and build a trap door entrance.
  • Use a clear fiberglass panel for one section of the roof to let the sun in.
  • Add windows in the other walls for extra light and ventilation.
  • Use asphalt shingles or other roofing material to make the tree house match the roof of your home.
  • Use a different material for the siding (such as cedar shingles) and add decorative trim to create a more ornate tree house.

A Playful Project

Once the tree house is built, your children will have a blast decking it out with kid stuff. It's a great spot for playing tea or a sleepover -- you might even find yourself joining in the fun!

Tree House Plan