To make this project easier, we had our timber pre-cut at Bunnings. Here's the cut list we used for this project.
90mm x 19mm merbau decking:
35mm x 70mm treated pine:
Get the four pieces of 430mm treated pine for the sides of the legs. Take a piece of 340mm pine for the top rail and clamp into place. Pre-drill with a 5.5mm drill and countersink bit before screwing into place with 2 x 100mm batten screws. Galvanised screws are good because they won't rust in the weather.
Measure and mark 100mm up from the bottom of the legs. Pre-drill with the 5.5mm drill and countersink bit. Secure the bottom rail with 2 x 100mm batten screws on each side. Repeat the previous two steps to make the other leg.
Once you've made the legs you need to attach rails at what will become the front and back of the seat. Clamp the timber to the leg, before pre-drilling with a 5.5 mm drill and countersink bit and secure the rail with 65mm batten screws. Attach to both legs. Use one screw on each rail.
Measure and mark the centre point between the bottom rail on both legs. Clamp and fix the centre rail with 65mm batten screws.
Turn over the bench frame so the top of the frame is on the workbench, then measure and mark the position for the two supports, which fit between the two longer sides. Ours were placed 435mm in from both ends. Pre-drill using the 5.5mm drill and countersink bit before screwing into place with 65mm batten screws. Use one screw on each support.
Make the first cut and then measure 485mm from longest to shortest edge to make the mitre cut. Set the drop saw for a 10-degree mitre cut. These mitre cuts are parallel to each other at each end. Repeat this process for the three other back supports.
Once you've cut the back supports, you need to attach them to the frame. Clamp the first one in place so it sits flush to the underside of the supports on each leg and in the top of the seat frame. This'll ensure the supports sit at the correct angle. Pre-drill with the 5.5mm countersink bit before screwing into place with 50mm batten screws. Repeat this for the other three back supports.
To attach the decking boards, start at the back of the bench seat with the first board. There'll be some overhang of the board at each end, over the legs and a little at the front. Make sure the board is straight against the back. Mark the position of the screws, two for each decking board, pre-drill with the 3mm drill bit and countersink. Use the 50mm decking screws to attach the decking to the frame.
Place spacers between the first and second decking board. Pre-drill with the 3mm drill bit and countersink. Use the 50mm decking screws to attach the decking to the frame. Repeat this process to attach the rest of the decking boards to make the seat of the garden bench.
Place spacers on top of the seat and flush to the back support. Place a piece of decking on top of the spacers. Measure and mark for the screw holes. These holes will follow a straight line from where the screws are in the seat.
Use the drill and 3mm drill bit and countersink to drill the holes in the decking. Use the 50mm decking screws to fix the board into place. Repeat the previous two steps to attach the rest of the backrest.
Use the putty and putty knife to fill in the holes left by the screws. Leave the putty to dry.
Once the putty has dried use the orbital sander and 120 grit sandpaper to sand all of the bench. Wipe away any dust.
Apply timber oil to the decking boards. This will not only protect the boards but bring out the warm colour of the timber. You may need to apply more than one coat. You can also paint the timber frame if you like, depending on the look you want. Use masking tape to protect any parts of the bench you don't want oil or paint to go on to. Let the paint and oil dry.
Once the paint and oil has dried, it's time to put your garden bench into place. All you need is now is to sit back, relax and enjoy your good work.