I built an outdoor sandbox for the kids that's about 4' x 5' but haven't had the time to put a real roof on it yet. To keep the rain (and the poo of roaming cats) out, we have thus far been using a piece of plastic sheeting held down with a bunch of bricks on the edges, but we have to go out and empty a giant puddle of water from the middle of it after each rainstorm so obviously that's a temporary solution.
I would like to build an extremely simple and inexpensive lid/roof for the box that will last at least a few years. Shingles seem like overkill, but all of the ideas online that don't use shingles seem like they're going to fail as soon as they get wet (ie this guy who just painted an OSB sheet).
What would be a good material for roofing? Can I just tar some plywood? Would painting OSB actually work long-term?
Best Answer
Purchase a 4'x8' sheet of southern yellow pine (SYP) plywood that's been pressure treated for ground contact applications.
Typically that's an ACQ treatment at 0.40 or 0.60 pounds per cubic foot, and SYP because that species of wood accepts and retains treatment extremely well.
"Ground contact" is the highest level of treatment, and I chose it over the lesser "above ground" treatment because it is directly exposed to the elements, and the additional cost should be negligible for just 1 sheet.
You wouldn't even have to paint it, but if you do, use a paint designed/intended for use on treated decks.
The only thing I'd be concerned about is a finding a way to prevent the sheet of plywood from flying away during storms and periods of high wind gusts.
Depending on the thickness you purchase, it will begin to warp as the main failure mode, not decay or rot. To prevent that you may want to build a frame for it by screwing treated SYP 2x4s on the bottom around the perimeter, and maybe one or two running down the middle of it. Make sure the screws are short enough so they don't stick through the other side and poke little fingers when removing the sheet to play.