I’m planning on building swings for my kids according to this rough design that I came up with here.

Essentially it’s a very simple two posts, one crossbeam layout. The posts of two 12 foot 4x6s on either side and one more 12 foot 4x6 across the top. Side posts held together with two 2 foot sections of 4x6 anchored through all three pieces with two 12” 1/2 galvanized bolts.

Cross beam would sit on one of those two foot sections and in sandwiched between the two 12ft 4x6s on either side. ( Hope my description makes sense, I’ve included a crude drawing below which should help. )

My questions are.

1. Will the bolt plus support from the 2 foot sections of 4x6 that the cross beam will sit on be strong enough to support the beam and swinging children? Or do I need to consider notching?

2. With the design as calling for vertical posts, will that provide enough strength if I go down 3-4 feet with each of the side posts?

3. Any other tips for a first timer would be greatly appreciated!

enter image description here

  • 3
    It is extraordinary unlikely that will be sufficiently rigid with wood supports that are both vertical. Build a triangular A-frame for sufficient rigidity. Commented Jun 6, 2020 at 13:20
  • Oddly, this is the 2nd or 3rd question about swing-set type construction in the last week or two. If you look at the commercial swing sets sold in stores and installed in local parks, you see very few that are not of an A-frame construction. The few you will see like that have 8-10" diameter steel posts supporting them. There is a reason for this. You're not going to sue yourself if your design hurts your kids, but take it from those who are worried about being sued if someone else's kid gets hurt: Go with an A-frame.
    – FreeMan
    Commented Jun 8, 2020 at 15:45

2 Answers 2


4x6 is pretty rigid, and doubling them will help, you will need a deep footing though as there will be high repeated lateral forces on it. 3ft is probably not deep enough.

For this reason most swtngs have A-frame ends instead of plain verticals.

  • 1
    You're right 3ft isnt deep enough, 3 ft would be too shallow for a fence, and even wind loads on a privacy fence will pale in comparison to a swinging kid. Commented Jun 7, 2020 at 5:19

When I was looking for info about making a swing set I found a commercial "PS20 swing set" that requires concrete footers of 18x36"
I would use that as a point of reference and dig a whole at least the same size.

  • Hello, and welcome to Home Improvement. Thanks for the answer, but would you elucidate: is that 18" wide by 36" deep? And, you should probably take our tour so you'll know how best to contribute here. Commented Jun 8, 2020 at 15:50
  • 18" wide and 36" deep for each 10ft long post.
    – anm767
    Commented Jun 8, 2020 at 22:23
  • The set has two seats rated to hold up to 500 lbs each.
    – anm767
    Commented Jun 8, 2020 at 22:30
  • rent a post hole digger with an 18" auger
    – Jasen
    Commented Mar 20, 2023 at 2:25

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