Jonathon Wardman

DIY Sandbox: Sandpit Lid

Back in June I wrote about the DIY sandbox which my father and I built in the garden over summer. As the sandbox is out in the garden we obviously needed to cover it to keep the rain out. At the time we used a standard tarpaulin held down with bricks. I always planned to get one cut to size and use hooks and bungee to hold it in place but never got around to it. The temporary solution had worked through summer, allowing a little rain ingress but nothing major. That was until a couple of weeks ago when the UK was hit by torrential rain. I decided it was about time I did something about it.

The Plan

Obviously the roof of the sandpit needed to be waterproof, but it also needed to allow fresh air to get underneath. We had some condensation problems when using the more “sealed” tarpaulin, and we didn’t want to stop water evaporating from the sand on warmer days when we couldn’t open the lid. The plan was simple. I designed the lid in a similar style to the roof of a shed. A couple of beams to support it on the sides of the sandpit frame and give it a slope, a sheet of OSB3 to make up the main panel of the lid, and roofing felt to make it waterproof.

Building

We already had two substantial beams which had been rescued when demolishing the shed at the bottom of the garden. These were just the right length to make up the supports across the width of the sandpit. We cut notches out of one end of the beams to hook over the edge of the sandbox to make the slope. The other end just sits on top of the wall of the sandpit.

The sheet of OSB3 I ordered was 2400 x 1200. With the outside area of the sandbox being a little over 1200 x 600, and with the roof requiring some overhang, I needed to take the end off the board and use the off-cut to extend the bottom of the lid. Once it was marked up the circular saw made short work of getting the pieces cut to size. It was then just a matter of putting it all back together and screwing the OSB3 onto the supports.

This was the hardest bit working alone. Using the same decking screws as I had used to build the sandpit frame, I needed to screw down through the board into the supports. For this I needed to line the supports up in the right place, place the board, and screw down blind. Taking time to make sure everything was carefully measured and marked on both sides helped to line up the beams. Once screwed together I was able to give the lid its first test and place it on the main frame.

I wanted to ensure that rain (and creatures!) couldn’t get into the sandpit through the gaps left at the side by the sloping roof. I also wanted to make sure that there was still a flow of air under the lid to allow any moisture to evaporate. To do that I added some additional timber to the very outer edge of the sides of the lid. This has the additional benefit of helping to hold the ODB3 in place a little better.

The final step was simply to cover the whole thing in shed felt.

The End Product

The finished sandpit lid can be seen at the top of this post. The best part is that it only cost just over £35 (with the use of the recycled beams and decking screws). I also have most of a roll of roofing felt left over which can be used for another project. And it certainly does the job, but I’ll admit to one or two flaws.

The slope on the roof could be greater. When it only rains lightly there are issues with water pooling on the top. This isn’t too much of a problem as it remains waterproof, but it should be easy to fix by adding padding to the rear of the supports.

The whole thing is also pretty heavy and awkward to move around due to the size. I can move it on and off the sandpit, but my partner can’t. Using thinner OSB3 would have helped, as would lighter supports. As would, in all honesty, a smaller sandpit.

Now comes the test of the first (so far very wet) winter since we built the sandpit in the garden!