This project shows how to build a rope tree swing in the backyard for the kids including details for tying the specialized knots.
How to Build a Rope Tree Swing
Here’s the finished swing hanging from a high branch on the oak tree. My daughter really enjoys it, however I made it large and strong enough to seat two adults.
Rope Tree Swing Materials:
- Pressure treated 2in x 8in board, 4 feet in length
- 5/8in diameter hollow-core braided polypropylene rope, ~100 feet length.
- 3″ corrosion resistant deck screws, Qty: 10
- Sanding block
- Course and fine grit sandpaper
- 5/16in stainless steel quick link (working load 1760 lbs), Qty: 2
- Gorilla Wood Glue
- Roll of kite string
- Oak tree
Choose the Correct Rope for a Tree Swing
The 5/8 inch braided hollow-core polypropylene rope I used in this project has a safe working load of 294 lbs. The “working load” of a rope is about 1/5 of it’s total tensile (or breaking) strength, and the tensile strength of this rope is 1400 lbs. In the next photo, the rope appears to be 3/4 inch diameter; under load it thins to 5/8 inch diameter. The only difference between the two ropes here is the color.
It’s important to use a large diameter braided rope for the swing. The use of a smaller diameter and/or twisted rope will be too slippery on the chain link and may cause the seat to tip over.
Nylon rope would be an upgrade over the hollow-core braided polypropylene rope used here because it’s a stronger (and more expensive) material.
A nice overview is of twisted and braided ropes is at Rocky Mount Cord Company, Inc.
- Cordless Drill/Driver
- Carpenter’s square
- Tape measure
- Carpenter’s level
- Butane Lighter
Hanging the Tree Swing from a High Tree Branch
Building the tree swing presented a bit of challenge because my 24 foot extension ladder wasn’t tall enough to reach the high and strong branch on the oak tree. Normally, I’d tie the rope to the tree branch using a Swing Hitch knot, but it requires putting your arms around the branch to tie the knot. The Swing Hitch must also be loosened and retied at least once a year so it doesn’t strangle and kill the branch as the tree grows.
Since I couldn’t reach the branch, I had to figure out a way to tie off the lines from the ground. I solved this problem with kite string and a Running Bowline knot.
Build the Rope Swing Seat
- The seat is a 36 inch length of 2in by 8in pressure treated lumber.
- The seat reinforcements are a 4in length of 2×8.
- Mark and saw the 36 inch long bench seat and the two 4 inch reinforcing blocks.
- Bevel (i.e. round off) front and rear edges of the bench seat with sandpaper. This is so the edges of the board won’t cut into your thighs when sitting.
- Attach the reinforcing blocks to the bottom ends of seat with Gorilla Glue and the five 3 inch wood screws. Notice the screw pattern is laid out to avoid the drill holes for the rope.
- Locate and drill the 3/4 in holes for the rope 2 inches from the outside end of the seat and 1-1/2 inches from the front and back sides. Here’s a closeup of the reinforcing block attachment and holes.
Tie the Rope to the Tree Limb
As described in The Challenge section, the tree limb was too high for my ladder and climbing the tree was possible. The solution for attaching ropes to the tree limb is a Running Bowline knot, a type of slipknot. A key benefit of a slipknot is it expands as the tree grows and won’t strangle the limb.
Not any knot will do when personal safety is at stake. The knots I used in this project are:
- Very strong
- Won’t significantly weaken the rope
To reach the limb, I tied a small rock to a spool of kite string and threw the rock over the tree limb, letting the string run off the spool. This took a couple of tries to get it where I wanted.
With the kite string looped over the branch, I tied the free end of the kite string to the 5/8 rope and pulled it back up and over the limb. You’ll need a double length of rope to do this!
Next, I tied a Running Bowline in the rope and pulled it up snug against the tree limb, all from the comfort of standing safely on the ground. Here’s the result:
Do the same for both ropes:
Cut each rope hanging from the tree limb off at ground level. Remember it requires a double length of rope to drape it over the tree limb and run the Running Bowline knot up to the branch. For example, if your branch is 20 feet high you’ll need 80 feet of rope (80 ft = 20 ft * 2 for the temporary double length over the branch * 2 for the branch suspension ropes). Adjust your estimates accordingly based on the height of the tree branch.
This project is continued in Part 2.
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