Need advice on a sandbox


Hi,
Here's my work in progress:
http://freeboundaries.com/sandbox.jpg
I have PT 4x4 in the ground (the kind that's safe to have, and it's been out in the rain for the past two months). They are kind of "single finger joined" as you can see in the bottom right. There are 5 screws in each joint.
Then I have 2x12 rails, joined the way you can kind of see (the front of the four rails is not yet installed). The joint is reinforces by 2x2x12 blocks glued in and screwed.
Two questions:
1. Should I drive rebars through the PT wood to make sure the base doesn't move? (The square shape is held together by 25 screws so I feel comfortable that it will stay together. But it might move although it is filled with 2+tons of sand. I guess I'm not sure why I would care if it moves a little.)
2. Should I caulk to gap b/w the 4x4 and the 2x12s? If so, what type of caulk should I use? Also, I haven't yet figured out how to fasten the 2x12's to the 4x4s.
Many thanks in advance,
Aaron
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"Aaron Fude" wrote

Thanks for the Pic! Makes it real easy.

I would not bother. I dont think you are going to need it.

From the pics, I'd use a galvanized outdoor angle bracket (lots of smallish ones) to attach as it seems the 4x4's are outwards a bit of the 2x12 box tops. Caulk will help the sand not leach to the yard if there is a gap. I think anything that expands and contracts well would do if made to stick to wood as well as other things.
Further suggestions unsolicited based on my assumption this is for toddlers to play in (grin).
- Paint each 2x12 in it's own bright primary color (red, green, yellow, blue). Paint the 2x4 under it in the primary color of the opposite side. Consider the 2$ or so plastic stencils in kid friendly large elephants or whatever catches your fancy on the sides in the same color as the 4x4 base.
- Check on the web for 'sand box treatments' or something to keep the sand safe. Even with a cover (highly suggested) you create a natural cat litter box etc. I seem to recall most toddlers who get worms, get them from sand boxes as transmitted from cats who go in there and left a little gift.
- At 12 inch tall sitting on 4x4, this seems almost a playpen construction? If toddlers are to get in and out on their own, it's a little tall. You may want to get some foam tubing and cut it open and line the top with that. I'm not sure how to secure it to the top, but it will prevent getting hurt if they fall getting in and out. If you plan to full fill it to the top and maybe add a step at one side, it's less of an issue (but too deep for safety if they arent walking yet, not that you'd leave one that age untended in such a thing).
- There seems to be plastic under the sand? If it rains where you are (the foliage suggests it does) this will mean wet caked sand, and ringworm. Remove plastic advised and use a cover to keep it dry as possible in rain (some will leach up in a good rain). Old wifes tale that is possibly true. Beach sand (even wet) doesnt have these problems because of all the salt? Dunno.
Anyways, best i can do there.
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On Thu 01 Oct 2009 05:24:20p, Aaron Fude told us...

I don't think you need to do anything to stabilize it. The collective weight of the wood and sand should easily stay in place since it's on a flat surface.

If you use a long bit to drill holes from top to bottom around the perimeter of the 2x12 rails and continue holes into the 4x4s, you could use rebar to secure the frame to the base. Should you want to, you can use rebar long enough to penetrate into the ground, thus stabilizing it as per your first question.
Use a heavy bead of clear silicone caulk underneath the 2x12s before laying permanently onto the base.
Instead of lining the box with any type of sheet plastic (this will retain water and keep the sand wet much longer after a rain), use landscaping fabric, perhaps several thicknesses. This is keep any type of plant growth from coming up through the sand, as well as allow for good drainage after a rain.
I would also suggest a wooden cover, either hinged or not, to anything and anyone out of the sandbox when it's not in use by those for whom it was intended. When I was a very young child the sandbox my dad built for me was covered this way and the sand was always kept clean. IIRC, the cover was made from 1x3s or 1x4s with a slight space (1/8" ?) between them to allow rain to run through, preventing puddling and rot that could occur on a solid surface.
HTH

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Wayne Boatwright wrote:

fabric - 2 thicknesses.
Thanks for all the other pieces of advice.
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Looks great! Good job. I wouldn't use any rebar to hold it in place. It isn't going to move. If you really must seal the edges, use liquid nail. It will glue/hold the wood together and fill in the gaps too. hey, its only a sand box. After your kids find a cat turd in in, they'll never get back into it anyway. :-)
Hank
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remember sandboxes useful life is only till a toddler grows out of it.
myself i would go with plastic lumber since its chemical free.
if in 10 years junior does poorly in school, and mom hears is from the supposed safe PT, now banned............
much better to avoid the issue altoigether and plastic sandboxes with built in covers are both cheap and nice lookiing.....
building stuff can be fun, instead why not build junior something that will last a lifetime like a play house?
it will get far more use than the sandbox he grows out of:(
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