DIY

Build a Sandbox

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With plywood, some basic tools, and our plans you can build a sandbox.
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Diagram shows dimensions to cut a sheet of plywood for the sandbox.
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With plywood, some basic tools, and our plans you can build a sandbox.
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Diagram shows method of assembling the sandbox's seat.

So you want to get the kids out of the house, but also don’t want to let them out of your sight. Build a sandpit? No, because you don’t want to dig up your lawn either. Why not build a sandbox instead? It’s simple and easy, although the grass underneath will die unless you make the considerable effort to move box
and contents every few days.

You can make a simple but serviceable wooden sandbox from a
sheet of 1/2″ thick plywood for the box and a cheaper 1/4″
sheet for a base. Cut one 4′ x 8′ sheet into three 16″ x 8′
strips. Bisect one strip into a
pair of 4′ lengths. Form the four panels into a 4′ x 8′ x
16″-high rectangular open-topped box (make it shorter if
you wish by trimming the long panels equally).

Fasten 2″ long wood-lath stakes at ends and every two feet
along the outsides of plywood panels, and hammer stake ends
into the soil to hold the panels down. Fasten the
galvanized-steel right-angle truss plates you bought from
the hardware store inside each corner–running
self-tapping drywall screws through holes in plates, through ply panels, and into end stakes.

Make triangular corner seats with scrap wood cleats
fastened underneath to fit the edges of the plywood sides.
Glue and nail the seats to the ply and corner stakes, and
sand the seat–the edge facing into the box
especially. Finish seat and box with paint or outdoor
varnish to bind in any potential splinters.

As an additional antisplinter measure, around the upper
edge of all four sides, fasten wood molding or plastic
bumper material from a boating-supply store (or collect
three or four old bicycle tires; cut in half, snip
sidewalls every few inches and staple around ply). You can
install the sides around a second sheet of ply (with an
inch trimmed off one end and one side) laid on the ground
if you want to be able to shovel out the sand easily. There
is little point of fastening bottom to sides.

Be sure you use outdoor-glued plywood that is smooth and
splinter free, “finished-one-side” for the upper surface of
the bottom sheet and inner surface of the sides–where
kids will scoot around and might get splinters. Before
beginning construction it is best to seal both sides of your plywood with a clear, weatherproofing finish to bind in
splinters and retard decay.

A Wood-Beam Sand Crib

I’ve built plenty of plywood boxes, however never to hold
sand. The one time I did build soil bins above ground was
to contain compost mixed with glass cullet made by crushing
old bottles (this was in 1969–just before the first
Earth Day when municipal recycling began to catch on). I
used it to grow lovely, straight carrots, but the design
would make a sturdy, quick, and easily
disassembled/recycled sandbox.

The carrot crib was made of stacked 8″-square, 8′-long
fence posts sawed from native Northern white
cedar–which (along with redwood and red cedar in the
West, Osage orange in the Midwest, and others) just
naturally resists the terrors of bugs and rot. Cheaper is
pressure-treated lumber used in ground-contact
construction. However, the pressure-treatment contains
copper and arsenic, two metallic poisons that I didn’t want
near the carrots and you surely won’t want holding in your
kid’s sand pile.

I notched the ends log cabin-like with the chain saw
and stacked the posts three high on a flat and level area
of sod. Their weight held them in place, but they were
warped enough to wobble, so for good measure, I drilled
3/8″ holes down through the corner joints and dropped in 6″
spikes as lock pins.

To get sand, I recruited an assortment of kids and made
them sit quietly in the pickup truck bed while we drove to
a natural gravel and sand bank. After the kids chose the
best sand in the hill, we all started shoveling it into
buckets and dumping it in the truck. We picked out roots
and clumps of sod and rocks large enough to do damage in
small hands. Back home after a stop at the swimming hole,
we dumped the larger rocks into the dry well I’d sunk in
the center of the pit, then shoveled in the sand. It took
three loads–wet sand and a half-dozen wet, bouncy
kids being heavy enough that a third-of-a-yard (9 cubic
feet) made the truck’s rear springs complain a little.

If you don’t have a truck, but live near a natural sand
deposit, you can haul it buckets at a time in the trunk of
a car. You may be able to get road sand from your town’s
landfill or highway department. Or, you can order it hauled
in a dump truck from any aggregate or traprock supplier to
the building trades. Clean “sharp” sand will be stone and
dirt free. Or as a last resort, in-town pool and outdoor
furniture retailers sell white beach sand in bags for city
kids who need sandboxes as much or more than country kids.

Cat Prevention

The neighborhood cats may try to adopt a sand pile as a
giant kitty-litter box. Don’t let it start. Besides being unaesthetic in the extreme, cat feces may contain human
pathogens and parasites and you surely don’t want the kids
playing anywhere near it. Our dogs woofed cats out of the
yard during the day and the kid’s green-eyed, orange
she-cat chased them away at night–and, once she’d
joined the kids playing in the sand a couple of times, she
seemed to prefer the loose soil of our garden to the sand
pit. But, I kept a constant check on cat activity. On the
way in from the garden every evening, I’d smooth the sand
with the garden rake. If I’d ever seen signs of a digging
or romping cat, I’d have raked and hosed the sand clean and
put on a cover.

The best sand cover I know is one of those inexpensive
blue, woven vinyl tarps you can get for a few dollars at
any hardware store. Leave one over the sand anytime it’s
not in use, holding it in place with stones all around or
wood planks on top. The kids will be able to remove it and
(if you nag them long enough) replace it. If rain water
pools on top, burn a few small holes through the middle
with a small flame or soldering iron. (The heat will seal
the edges so the hole margin won’t ravel and enlarge with
use.)