6x6 Post Swing.

Hi guys. i'm in the HVAC trade, so i dont know alot about carpentry. I need some advice on building a swing set for my kid and myself. I am going to make it out of treated 6x6 posts. I was thinking putting 2 6x6 poles in the ground and resting another 6x6 on top for the beam and bolting it together using steel plates on each side . So far I have just three questions.

1. how deep should the posts be in the ground if i plan to have 10' above ground?

2. Will 8' span between posts be ok using a 6x6 as an overhead beam, or is that too far apart?

3. How can I prevent the beams from twisting and bowing over time?


Thanks guys.

Try this Good luck

1. Kinda depends on soil conditions, here 3'-4' would be plenty.

2. Kinda depends on how heavy the swing is & the people going in it weigh. Unless you're huge the 6x6 should work.

3. Don't use treated pine, some braces will help tho.

Greg, not exactly what I was looking for. Thanks anyways.

Soil here is pretty hard.

Most of the playground kits I have seen use a 4x6 for a beam. I would think the 6x6 is much stronger. Just wasn't sure on the span size.

what other options besides treated pine?

I just read on another website that said laminate posts will resist warping and twisting and are stronger than solid 6x6 posts. What are laminate posts?

Treated Laminated posts might help with the twisting, but they are going to be expensive and availability might be suspect. I haven't seen any at my local yards. Probably a special order.

The 6x6 should span that fine, assuming that your connection points are towards the posts and not in the center.

4' deep with the concrete should be fine.

I prefer to do them like this, for more stability and good looks.

what about making my own laminate posts using 3 2x6? just glue, clamp, and screw.

that would be a 4.5 x 5.5.
I'd trust it to swing on. How many seats?

i guess 4.5x5.5 would be sufficient . you can also try HVAC forum for better answers

3-4 ft deep with concrete.

6x6 posts braced at the top will have minimal defect.

use a few laminated 2x8's or 2x10's notched/bolted as a beam across the top.

Would kiln drying the PTed 6x6 posts help keep it from twisting?

Here's another idea...

I would suggest using an A-frame rather than single 6x6's. The A-frame members could be 4x4 pressure treated embedded in concrete say 2' deep x 2' diameter. You want plenty of concrete weight to counteract uplift when some fat guy really gets to whipping :-) Miter cut the posts where they come together at the top so that you wind up with a flat top on which to set your beam.

A 6x6 hem fir, pressure treated beam, if spanning 8', can easily hold 500 lbs (I calc'd it). And that's even with the bolt holes through the beam on which the chains attached.

The hard part will be the connection of beam to posts. I'd use a TP57 (5"x7" metal tie plate) on each end, oriented long dim vertically, with 1-1/4" galv screws, and also a ML26Z (angle with SDS screws) on the underside of the beam where it sits on the posts.

Sounds like fun!

When I built our swing/fort 20+ years ago, I went the A frame rout, 4x4 A's, with 4x6 horizontals for the chain swings. It worked out nicely. My air plane mechanic neighbor wanted something cleaner looking & came up with an excellent solution. He used 2 vertical 4 x 4's spaced with 4x4 blocks at the top, center, & in the ground, & through bolted, so as to create a 3 1/2" x 10 1/2" thick vertical. It looked clean, & was very stable. He said air plane frame girders were what gave him the idea. It kinda peeved me off that a mechanic came up with something so original. I've yet to see anyone else do one that way.
Joe

I dont like the A frame look.

After looking at my plans, it looks like i will need to put the post 10' apart instead of 8'. 8' will not allow enough room to pout 2 swings and still have 2' of clearence between the swings and 2' between swing and post.
Hopefully adding 2' to the span wont make any difference.

I'm going to use 16' beam and leave 3' of overhang on each side. The brackets I plan to use to attach the post to the cross beam is going to be custom made steel plates in a "T" shape. One on each side for a total of 4. Bolts all the way through it, so the post and beam will be sandwiched between the "T" Plates.

If 10' span is too much I may build a beam out of 2x10's, but the guys at the lumber yard says 10' is no problem for a 6x6 since there will be very little load in the center.

Local lumber yard said I should use Douglas Fir. He said its stronger and will last alot longer than SYP

Make sure that it is treated for ground contact, if it is going in the ground.