Tips on embedding posts for playground

I'm going to be building some heavy duty play equipment in the backyard (monkey bars, climbing wall) and need to bury some post ends. I read that the golden rule is to embed 1/3rd the height of the post, and galvanized nails or lag bolts into the bottom of it to hook up with the concrete.

What's the best way to avoid "slop" of the posts? I may hand-dig them. I know that cardboard cylinders (Quik-Tube, Quick Tube, Sono-Tubes, Setting Posts, Building Form, Forms by Quikrete) are generally used for posts. However, if I regularly soak the ground I assume I don't need this? Also, wouldn't my posts "key in" to the surrounding ground better if I just put the post in place and pour concrete around it without the cardboard cylinder? The force on a deck is pretty much all vertical, but I'd have a decent bit of horizontal force in my application so I do need it in the ground pretty darn snug.

I have a 32-36" frost line, but no need to worry about permit for what I'm doing. My ground is exceptionally hard to dig into and I would hate to go deeper than I need.

Thanks for any ideas on how best to secure these

 

IMO, you would be just a well off embedding the posts in holes without the use of a sonotube. I would make the holes wide enough so you could get a good stand of concrete to surround them. I, also would build all the stuff, with the posts embedded, THEN poke in the concrete. That way you would be sure to achieve plumb on all your posts when they are connected together. You could embed the posts, plumb and measure them off, but once the concrete sets, you won't have slop enough to adjust them.

 

I wouldn't have thought of it on my own but I like Chandler's idea of building the structure first and then filling the holes with concrete; I'd definitely do it that way.

 

For play equipment...why even use concrete? This isn't a fence that has a huge windload and no triangulation for rigidity. You could just dig the holes..set the posts, build the rest of it then fill the holes back in and tamp tamp tamp every 6 inches of fill or so.

You might also make a "T" on the bottom of the post using some t-brackets and a piece of treated 2x4 or similar.

Of course it depends on what your actual design is.

One thing to remember...kids grow up pretty fast. Unless you have a huge family with a lot of kids or it's for something like a playground or daycare.....it will get use for a few years...then just sit til you decide to pull it down.

I think my dad really regretted spending so much time and effort to build me a freestanding tree house when I was 8 or 9. 3 yrs later its may as well been scrap wood. I'd moved on to other stuff. No grand kids so I doubt it ever got used again. As I remember a neighbor demolished it with his loader about 15 years later.

 

Yes, that is indeed a fine idea, Chanlder, thanks! Makes total sense.

I was going to use concrete because I want this absolutely damn strong, rigid as heck. I want it to feel like the unmovable equipment at playgrounds next to schools, for example. Also, I may be building a climbing wall that is simply a rope net between two posts and if I do this it will need to be anchored to avoid any wobbling I suspect.

You're very right, gunguy--that is why I want to get this built this summer. A few years from now it will be merely an ornament. I already built a pretty serious swing set a few years back because I was unable to find--even in the very expensive ones made of wood--anything up to snuff. Cost me about $100 in wood and my kids still regularly use it (every day). I think that's because it's a serious swing set, doesn't rock, is high enough to get good swing on it. Hoping to get the same out of this stuff

Regarding the tree house, I had thought of building something along those lines, but when I look around my neighborhood I see no kids using them more than the first few times they are set up (just like slides--no kids ever, ever, ever use slides that come on the typical house-size play set). It's too bad yours wasn't built when you were five, because you'd have had 5+ years of use out of it. We were at some old folks' home last week and the previous owner had built a very impressive platform 10' up with a drop down ladder. They have no grand kids, though, so my kids had a ball but was the first time it had been used in years, I think.

Wow, digressing

 

Done Got the set built this past weekend. I did set one post initially and then the next day hooked the monkey bars to that, and set another post that day (so that only one half of it was connected). The day after that I set the other two posts, and as I was connecting the ladder to the posts prior to concrete everything was nice and snug with no weirdness.

Construction consisted of 4X4 posts and then the ladder was 12' long 2X6" on either side with 1" galvanized steel in between them every foot. Had a guy at Lowes spend 15-20 minutes cutting my lengths from 10' sections.

The posts I set into a thin bed of gravel and prior to putting the concrete around them had drilled 1/4" holes through the bottom, through which I hammered a 60D galvanized nail, this way it's impossible for the post to move vertically independent of the concrete. This was possibly overkill but each of those nails was something like 16 cents

Materials and wood ran around $200.

 

I'm all about overkill

Thanks for the update

 

Your camera broke??? http://www.doityourself.com/forum/el...your-post.html

 

Will be bolting the post next to the swing set into the swing set, which will end up giving both more stability.

I'll keep an eye on the wood. If I think there's too much splitting at the end where the ladder attaches to each post I'll screw some short 2X4 ledges to the posts, so that the ladder additionally rests on them.

The holes for the steel are offset from center by design. However, my original idea was to have the bolts (each one has a single bolt going through it from bottom--out of picture in this case) at the top so that there would be more wood "below" each hole. Then I thought I'd flip it so the top is smooth. Again, I'll keep an eye on wood splitting and if I think it's too much I will sister a 2X6 to each side, which will give it more strength and also cover the holes.

As it is right now though I can go across it without issue and I weigh the same as several small children

 

Now, you're talkin'. Only thing....cut those carriage bolts off as flush as you can and grind them smooth.

 

Wondering...whats holding the monkey bar tubes in?

 

I do plan on cutting those carriage off. Had thought of cutting the top of posts and ends of ladder, but may keep them there as a little extra wood.

Through the bottom of each bar end, through the wood and then into the bar is a 1/4" hole, and I have a bolt terminating inside of the bar, within which it's secured with a nut. Was pleasantly surprised at how easily this steel is drillable.

 

Just out of curiosity, what would be the tallest structure I can build without attaching support columns to sonotubes?

My 5 year old son wants a square fort (base) that is 6 feet high with climbing net, rock wall, slides, etc. (what can I say, he is an active little boy). He wanted a 7 ft platform but my wife vetoed that idea.

I figured with a 6 ft platform with roof on top would be about 12 ft in total.

I think a triangular base would provide good stability without attaching to the ground but he wants a square one.

I am concerned that a strong gust of wind (which happens often in my backyard) just might tip off this thing.

I do plan on using 6x6 support columns though.

I hope I did not hijack OP's post.

 

Yeah, you hijacked it, but here's a quick answer:
Don't cheap out. Sink the posts in the ground, use concrete to stabilize them and build a quality fort. You already have your parameters as to height, dictated by a higher power Nothing is worth compromising safety. You'll have several activities, so I imagine it won't be a postage stamp fort, but will require a good bit of wall space.
If burying it is out of the question, at least anchor it with screw in type rods and attach them firmly to the inside of the posts.

Attachment 1900

 

No hijacking concerns here!

If you build any sort of a square shape and put diagonal supports in place you'll end up with a ridiculously strong structure

Wind is a concern. I've seen one or two play sets, including my immediate neighbor's blow over in heavy wind.

Even some shallow holes filled with some concrete and hooks coming out of it that attach to the play set would completely mitigate such concerns of blowing over; don't even need to bury the posts. Possibly even more simply if you can find some stakes that dig nicely into the ground and hook to those they'd take care of wind concerns. A metal play set I once bought came with 15-18" metal stakes that had a ring on one end and an auger type shape on the other (the ones in chandler's post). There was nothing ever so comical as thinking those would work in my soil, however, which requires a pick to gain any headway into, so they hang in my garage. I couldn't get them in for the life of me. I found some other stakes in the meantime that let me use a hammer to put in place.

You could also look at those $40 (?) things they sell at home depot. You hammer with a sledge into the ground at least two feet and set your 4X4' posts into those. As long as you can screw the 4X4 into the bottom of them that play set won't be going anywhere.

 

Skoorb, trick......Big SDS hammer drill and a home made bit with a yoke on it to go over the hole part. Drives like a dream.

 

thanks for the input.

regarding ground spiral stakes, my backyward is so rocky, i doubt i can get them to securely lock into the ground.

i recently built a deck with 6x6 posts set on 14" sono tubes and have some leftovers so maybe i can use up some of those materials. no, i will only go down to maybe 24 inches or so but i don't think i should worry about frost heaving for a playgym, do i?

thanks again!

 

Unlike a deck it's no huge catastrophe if the playground moves a little IMO (though it's not ideal and if it moved much it would move the fasteners a bit). FWIW my frost line is 30-35"--though I understand frost lines are worst case, so it would rarely get that low. I went about 29-30" on my holes. I simply got sick of digging with the approach I was using. Another 6" would have been ideal but it is what it is.

In fact, this is one of those rare cases I just cut a corner, frankly. It doesn't happen often, but I truly don't see my stuff moving to any discernible degree.

BTW at the beginning of each season I do check my existing swing set for damage--make sure it's good and if it can hold my weight it's ok for the kids. Whatever you built should always be plenty sturdy to take an adult.

 

This string has been so helpful to the DIY commoner
I have noted down various comments i.e. galvanized nails at base, bed of gravel etc.
Took down the huge old prefab playset and have bought wood for a more modern style. I wanted something TALL and have bought 4x4 x 16ft with a cross beam of 4x8 x 14 feet. The structure will look like the photo. But now I am concerned that this could be too tall and not safe? I will dig 4 feet down (we live in the Rocky Mountains) to bury the doug fir 4x4's. Does this sound safe and strong enough? There will be two swings, one handle bar and one skateboard swing.
Thanks!!!!

 

Although I started this thread re. monkey bars, a few years prior I built the biggest baddest swing set in my neighborhood with a classical A-frame shape and heavy lumber. Kids still use it. It's awesome. I don't think you can go too tall. Basically, make a swing set an adult could use, and then just change the swing height over time.

That looks quite safe to me. The only thing worth noting is that even four 4X4 will move quite a bit that far off the ground--more than you might think. The one thing that should mitigate that is the piece in the middle, as I think if it's tight enough it may try to lift the side that is now pointing up, and so stiffen the entire thing. If you're willing to use concrete it's a much simpler setup than building a set out of a ton of lumber. Worse case you find it sways more than you want and you could put two diagonal braces in later on, also embedded in concrete, then you'll be good.

I'm happy to report no noticeable movement in the posts I put in back in 2012 even though last winter in particular was just hell on heaving in our area.

Not sure if I mentioned it above, but I kept the concrete a few inches from the top of the holes so that in the future when kids are grown I can just cut the wood off at the concrete line, soil over it, and grass will grow without ever removing the conrete.