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Obviously, building a tree house is no small task--it must be done right for safety sake, and so you don't create an eyesore in your backyard. Hint: If you don't have much building experience, find a friend or family member who is handy, and willing to lend a weekend of his or her time. And then you must have a good stout tree with branches that spread in a V-shape, and is located away from power lines, the street, and other potential dangers.

Before you start on a design, go to a building supply store to find out how much all of the materials will cost. Listed below are the materials needed and the estimated cost that we came up with (prices vary according to location and store).

Materials

• Two 40 lb. bags of concrete mix: $4.65 • Two 6" lag screws: $1.35 • 3" galvanized screws, three packs of 20 each (for roof, balusters): $6.27 • Two pounds 3 1/2" galvanized nails: $2.75 • Five pounds 2 1/2" spiral deck nails: $6.85 • Plastic tarp for roof: $3.00 • Two 4'x 4'x 16'(for posts): $24.54 • Seven 2'x 6' x 8' (for frame, joists): $24.64 • Fourteen 5/4'x 6'x 8' (for floor): $87.00 • Four 2'x 8'x 8' (for railing): $19.80 • Twenty-eight 2'x 2'x 8' (for balusters, roof): $53.48 • Five 2'x 4'x 16' (for diagonal supports, ladder, rungs): $21.50 Approximate Total:  $255.83

	Tools
	Goggles, Plumb line, Dust masks, 2-foot level, Reversible drill, Jigsaw, Hammer, Handsaw, Combination square, Tape measure, #2 Phillips head screwdriver, Posthole digger, Steel wheelbarrow (for mixing concrete), Shovel, Extension ladder

LUMBER BUYING TIPS:
1. At the lumber yard, "sight down the wood"--that is, hold one end of the board up to your eye and look down its length for unwanted curves.

2. Inspect the wood for knots, and not just for aesthetics. Knots warp the wood, and they're hard; your nail hates to hit one and so will your arm.

3. For the wood, choose pine; a soft, abundant, inexpensive wood; treated with arsenic--a handy dosing that retards bugs' interest. Otherwise, termites and carpenter bees bore in and lay eggs. Redwood would be ideal, a durable, light wood that bugs find naturally repugnant, or a hardwood like oak, but they are both more expensive.