Step One

You will need to cut the deck joists in this step, the joists will form two square frames that'll sit one on top of the other. Start by measuring and sawing the eight sections of deck joists: you will need to cut x4 one metre joists and x4 of 1.056m joists.

It is wise to use a thick pencil when marking out your lines and consider using the back of a Mac Allister hand-saw to draw those straight-lines

For each of the frames you'll need two one metre joists and two 1.056m joists. The difference in measurements allow for the overlap at the corner joins.

When joining the first box together you'll need to drill pilot holes at each corner to help guide the 100mm galvanised nails through. Continue to secure all four joists together to form the first square frame and repeat. I was using my Mac Allister for the first time on this project. The drill and in fact the Mac Allister range (Hammer, tape measure, saw, etc..) were all quailty and if you consider the price compared to other brands then the Mac Allister range punches above it weight each and every-time.

Step Two

Once you have the boxed frames secured lay one of the on a level-surface and mark out each corner with a long cane or stick. You will need these markers to ensure you secure match both frames together and outline the hole.

You'll then need to dig a hole in the garden, it is recommended you find an clutter free area. When digging the hole you'll need to consider how deep you want to place the sandbox in the earth.

Once you're happy with the hole put one box frame on top of the other, if you have clamps freely available clamp them together, making sure they're flush and square. If you do not have clamps ask someone to help you secure the frames together, asking them to hold each section in place until you have added the metal plates in either the middle of each side secured with 25mm galvanised nails or like me use metal corner pieces; secured between the two frames.

Step Three

Now that you have the two frames secured together the next step is all about forming a seat around the top of the sandpit for the little ones to sit on whilst playing.

To make the seat, take the remaining four 28mm x 144mm pieces of deck joists. You then need to cut one end of the decking to a 45 degree angle; most hand-saws will have a 45 degrees angle that should help you draw an accurate-line each time and again ensure you use a thick pencil to mark out the lines.

I admit that this step is tricky, if you have a work-bench then secure the decking down. If you can't get access to a bench then you'll need to make sure that you have a level surface to cut-form and have an extra pair of hands to hold the wood when cutting, this will help you follow the previously drawn-line.

Step Four
After the first 45 degree angles have been cut, you'll then need to go on to cut the other ends accurately. To achieve an accurate fit line the deck boards up and and around the box, one at a time.

Align the  first angled end with one corner and mark the point where it touches the next corner.

Use this as your starting point for cutting the other end. If the box is exact, the inside, shorter edges of the frame sections will be exactly one metre long.

Step Five

After edging the joists it's then time to join them together. Find a flat surface, i used the existing frames, glue the joints together with a strong waterproof wood adhesive.

To offer further support to the joint you need to nail the perforated metal plate across the joists using 25mm nails.

Here i found that a lot of the glue escaped and i had to wipe the surplus glue away with a damp cloth.

Step Six
Once each of the angled corners are bonded, you'll then need to drill pilot holes and fix the seating to the box.


Use 75mm countersunk deck screws to secure the seat on to the frame, start in each corner to avoid any potential for movement - i used x4 machine screws in each panel. It is essentially at this step that you make sure that the seat is aligned with the frame, failure to do so will result in the seat being set back from the frame; therefore looking uneven and untidy.

Once you have secured the seat fill in the holes with a wood filler and sand them smooth to remove any splintered wood.

Step Seven
Now that the seat is secured, bonded and filled it is then time to paint the seat and frame if you wish.

I decided to only paint the seat, it needed two coats as the groves in the joists were deep so the colour didn't come out as bold as we would have liked to have first time round.

Step Eight

Once the seat/frame had dried you can then start to think about attached a sheet of heavy duty plastic or weed control fabric to the bottom of the frame.

To do this simply turn-over the frame, measure and cut-out the material and secure it using evenly spaced 10mm felt nails.

We used both nails and staples to secure our sheet, we even doubled up our sheet to add a little bit of extra strength.

Step Nine

Before lowering the finished box into place it is advisable to scatter a thin layer of sand into the bottom of the hole.

You will also need to ensure the ground is level before securing the pit into place.

If you're using a plastic liner then you will need to perforate it with a garden fork. Make plenty of holes these will allow for drainage and prevent the sand pit form becoming soggy.

Step Ten

Fill the sandpit with play-sand, x4 bags will provide a thin layer of coverage but i used x8 as my boy likes to build hundreds of sand-castles.

It's good idea to cover it when it's not in use to stop it getting waterlogged. You can either use the left-over plastic sheet or even look to source a lid for the frame.




As you can see from the photos below my son loved playing in the sandpit for the first time yesterday. We have a lot of family and friends with younger kids so i am sure the sandbox will be well used week-in week-out.