Building and Supporting the Floor Frame Brad Staggs, host of DIY Playgrounds, provides step-by-step instructions for building a children's tree house. Project Plans Materials: Pressure-treated pine lumber: 2" x 6", 2" x 4", 4" x 4"
Exterior-grade plywood
3/4" tongue-and-groove plywood for flooring
Joist hangers
Miter saw and miter box
Fast-drying concrete
Asphalt shingles
Drip molding
Exterior latex paint
Door hinges
Marine rope
Galvanized screws
Galvanized nails
Galvanized lag bolts
Two metal corner brackets
Circular saw and beam-cutter attachment
Power drill with screwdriver attachment and spade bit
Router and piloted router bit
Posthole digger
Speed square
Framing square
Carpenter's level
Tape measure
Bar clamp
Pencil
Ladder
Safety equipment: safety glasses, dust mask, work gloves, protective clothing
Your tree house will be exposed to the elements, so use materials that resist moisture, rot and insect infestation. Pressure-treated lumber lasts longer than ordinary lumber because it has been specially processed to resist decay and insects. Likewise, nails, screws and other fasteners that are galvanized (zinc-coated) resist corrosion and are less likely to cause rust stains in the wood. Because pressure-treated lumber has been processed with strong chemical preservatives, you should wear work gloves, long pants and other protective clothing when working with it. When cutting it, wear safety glasses and a dust mask. Dispose of scraps and sawdust properly, keeping them away from children and pets. Never burn the scraps. When working with power tools, wear protective eyeglasses and ear protection, and follow the manufacturer's safety recommendations closely. Select a hardwood tree (e.g., an oak, a maple or an ash) to which you'll attach the tree house. Don't select an evergreen such as a pine or a cedar. Securing a structure to a tree may damage the tree, so avoid building onto a prized tree or one too near a house or other building. Choose a tree that's at least 16" in diameter. The structure of the tree house will be braced against the tree on one side and supported on the other with 4" by 4" uprights sunk in the ground and set in concrete. This project involves digging, so before you begin you should contact your utility company to make sure you won't damage any buried water, gas or sewer lines. Building the Frame The frame for the platform floor is an 8' by 8' square constructed from pressure-treated 2" by 6" boards attached with butt joints. - Cut two of the rim joists to 8' and two to 7' 9": the shorter lengths allow for the width of the adjacent sides.
- Use 3" galvanized screws to attach them. Once the boards are butt-jointed, they should form an 8' by 8' square.
- On the side that will be attached to the tree, drill three pilot holes in a triangular pattern to accept the lag bolts that will anchor the structure to the tree.
Elevating and Mounting the Frame Now you'll elevate the frame with upright supports and mount it in place. - Attach a brace of pressure-treated 2" by 4" onto the tree at the desired height. (Ours is about 1' long, attached at a height of 8'.) With the help of two or three friends, lift the base and rest it on the brace (figure A). With the center of the frame resting at the center of the tree, attach the frame to the tree with a single screw to help hold it in place while the frame is being leveled.
- Stand some 2" by 4" or larger pieces of lumber on end, and clamp them to the frame to serve as temporary braces until the 4" by 4" corner uprights are put in place and secured. Use a carpenter's level to make sure the board attached to the tree is perfectly level, then stabilize it with a second screw. Level the remaining sides, and clamp them to hold them in place (figure B).
- Once all four sides of the base are level, attach the structure to the tree with 6" galvanized lag-bolts.
- Position the 4" by 4" uprights inside the rim joists in the two corners opposite the tree (figure C). Use spray paint to mark the locations where you'll dig holes in the ground.
- Use a posthole digger to dig holes about three times wider than the diameter of the posts and deep enough to extend below the frost line. (The frost line varies, depending on the area of the country. Our posts are set about 24" deep.) Tamp the sides and bottom of the holes so that the walls will be firm.
- Add a small amount of fast-drying concrete mix, followed by a little water, to help hold the posts in place while you work.
- Using a level, plumb each post (figure D) on two adjoining sides to make sure it is perfectly upright before attaching it with clamps to the rim joists (figure E). Clamping the posts in position will keep them secure while the concrete sets.
- Add dry concrete mix to each hole, adding water gradually, until the hole is filled to about 3/4" from the top (figure F). Allow the concrete to set and dry according to the manufacturer's recommendations.
- After the concrete has set, attach the rim joists to the post with lag bolts (figure G) set in pilot holes. Cut the excess from the top of the uprights so they're level with the top of the rim joists. Remove the temporary uprights that held the frame in place while the 4" by 4" uprights were being positioned. Now that the concrete has hardened, fill in the top of the holes with dirt.
- For added stability, install metal inside-corner brackets (figure H) in the two corners that aren't supported by 4" by 4" posts -- that is, the corners on either end of the rim joist bolted to the tree.
Floor Joists The flooring system for the tree house consists of floor joists installed on 16" centers (at 16" intervals, with each joist centered over the inch-mark) and topped with tongue-and-groove plywood decking. - Cut 1" by 6" boards to size for the floor joists, and install them on 16" centers, using joist hangers (figure I). Install all but the center floor joist: the trap-door opening will be located in the center section. The center joist will be a "cripple joist" -- one that's shorter than the others.
- Measure between the two center joists to get the inside dimension of the center section. It should be about 30 1/2". Cut and install 2" by 4" cross braces in the center section -- the first 1' off the tree and the second 3' off the tree--to form the opening for the trap door (figure J). Attach them with galvanized screws. Install the cripple joist extending from the inner cross brace to the rim joist.
- For added support, cut two 2" by 4" diagonal supports (figure K). These will be connected to the tree at their bottom ends and to either end of the rim joist that's bolted to the tree at their top ends. Miter-cut the bottom ends of the 2" by 4" boards so they fit together well. Attach them to the tree and rim joist with lag bolts. These supports help transfer some of the floor's weight to the tree.
Flooring Once the braces and joists are secure, install the 3/4" tongue-and-groove plywood flooring. - Have a friend help lift the flooring onto the joists, and position it.
- Attach the plywood to the floor joists with galvanized nails or screws. Screws are recommended because they're less likely to work themselves loose as the structure moves.
- Use a spade bit to cut a hole through the plywood inside the frame for the door opening. Cut out the opening with a router and a piloted router bit (figure L).
- To reduce wobble, you may want to add diagonal braces, miter-cut at 45 degrees and connected between the 4" by 4" uprights and the bottom of the rim joist (figure M). Attach the braces with galvanized screws.
Walls and Windows Build the walls in standard fashion: laying them out, assembling them and attaching them. You may need to make an exception for the wall adjacent to the tree -- the tallest wall, at 7'. Ours was fashioned slightly differently from the others to accommodate the tree trunk. The other walls' studs were set on 2' centers, but the tree trunk was in the way where the center stud would've been installed. To solve the problem, we installed two studs in the center section, on either side of the tree. This had the added bonus of allowing the tree trunk to remain visible inside the house. We used a jigsaw to notch out the top and bottom plates slightly to fit snugly to the tree (figure N). - To build the wall opposite the tree, select two 8'-long pieces of 2" by 4" lumber for the top and bottom plates.
- Cut five 2" by 4" studs to a length of 4' 9". Place the studs at 2' intervals between the top and bottom plates, and nail them in place.
- Raise the wall, and secure it to the floor with nails between the studs (figure O). Position a brace on the outside edge of the wall as a temporary support, and secure it to the wall and floor (figure P).
- To build the two side walls, measure and cut the top and bottom plates, and find the center of each. These walls are positioned between two walls already in place, so they'll be slightly shorter than 8'.
- From the center point, measure out 2' in both directions, and mark for the placement of a stud. Position the last two studs at the ends of the plates.
- Nail in the studs, and raise and attach the walls in the same manner as before. Nail the walls together at the corners.
- To construct the windows, attach two braces between the wall studs. Use a level to make sure the braces are positioned properly (figure Q).
- Screw or nail the exterior plywood to the outsides of the walls. Leave the plywood sheathing uncut, 8' high. It will be cut to align to the angle of the rafters after they're installed.
- Use a router to cut out the windows in the same manner as the trap door (figure R).
Roof The roof is made from 3/4" plywood, covered with asphalt shingles and attached on 2" by 6" by 10' rafters secured to the front and back walls with "bird's mouth," or seat, notches. - Lay a 2" by 6" by 10' board that extends from the 7' back wall to the 5' front wall. Make a mark on the rafter 1' from the end. The board will overhang each wall by 1'. Align the mark with the inside of the top plate of the wall. Use a framing square, lying flush on top of the wall plate (figure S), to make a horizontal and a vertical mark for cutting the bird's mouth. Do the same at the bottom end.
- Notching out using these lines will permit the rafter to sit securely on the top wall plates (figure T). Once you've notched the rafter, cut off the top overhang so the end of the rafter is flush with the outside of the back wall. Leave the overhang on the front wall. Repeat the process for all of the rafters.
- Nail the rafters in place on 2' centers by toenailing: nailing at an angle through the side of each rafter into the top plate (figure U).
- With all the rafters in place, install the roof decking (figure V). The rafters are 9' long, so use 2 1/4 sheets of plywood. Position the plywood, and attach it with galvanized nails.
- Attach the shingles to the plywood. The first course, or lowest row, of shingles go on upside down. Then you'll place a row directly on top of it, right side up. The rest go on right side up, with the tabs of each row overhanging and covering the nails of the preceding. Position the shingles so the tab slits alternate and no plywood is exposed (figure W).
- For a clean edge that will help prevent water damage, install drip molding to the roof all around.
Trap Door, Ladder and Finishing Touches Once the structure is complete, you may want to protect it with exterior latex paint, watered down by 50 percent so the wood grain shows through, giving the tree house a rustic look. Make the trap door from a piece of plywood cut to size so that it just fits inside the opening (figure X). Attach it to the floor with door hinges. The trap door rests on supports framing the inside of the door opening. Drill a hole in the trap door, and insert a piece of marine rope, tied at both ends, for a pull handle. The ladder (figure Y) is made from pressure-treated 2" by 4" boards attached to the inside of the opening and running to the ground at a slight angle. The rungs are made from 2" by 4" lumber cut to length and nailed in place, with 9" spaces between them. The ladder also helps brace the structure.
RESOURCES :
Georgia-Pacific Information
For product information, click here.
For more Georgia-Pacific contact information, click here.
Georgia-Pacific Corporation
Atlanta , GA 30303
Phone: 404-652-4000
Fax: 404-230-5624
Website: www.gpplywood.com
| ALSO IN THIS EPISODE: | | Tree House |
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