Preparation
Step 1
Ensure that the ground at the base of your steps is firm and level. Place one end of the first stringer on the ground and lean the other end against the tree house platform with the 2-inch side against the frame. Adjust the stringer to a 60- to 70-degree angle. Mark the bottom end of the stringer level to the ground. Cut the bottom of the stringer.
Step 2
Put the stringer back up against the tree house platform. Mark a vertical line at the top of the stringer and cut on the line to fit stringer to the platform. Attach stringer to platform with 3 1/2-inch galvanized deck screws.
Step 3
Once the first stringer is cut to fit properly, use it as a template to mark and cut the second stringer.
Step 4
Fasten both stringers to the tree house platform 16 inches apart with 3 1/2-inch galvanized deck screws.
Step 5
Mark every 8 inches on the inner face of one stringer for tread placement. This will give you a rise, or distance between steps, of 8 inches. Using a carpenter's level, make corresponding marks on the second stringer. Extend a level mark toward the back of each stringer across the inside face. These layout lines mark the top of each tread.
Step 6
Cut 2 by 6 lumber to 16-inch lengths for treads.
Step 7
Set each tread in place with 3 1/2-inch galvanized deck screws driven through pilot holes drilled in the outside of the stringer. Ensure that the top of each tread is on the top of its perspective layout line.
Step 8
Reinforce each tread with a supporting 1 by 4 cleat. The cleats should fit at the end of each stringer from top of lower tread to bottom of tread above it. Use 2-inch screws driven through pilot holes you drilled to fasten the cleats to the treads.
Step 9
Finish ladder with a sealer for wood products, if desired.