There are two ways you can lay decking on grass. One method is quick and easy but it will be hard wearing on your decking. The other is more difficult but your decking will stay healthier for longer. We’ll talk you through both methods.
- Outline the size and shape of your decking. Hammer a peg at each corner and run a builder’s line between each peg.
- Clear away plants, rocks and weeds, and dig down to a depth of roughly 50 mm. Clear away the turf so you’re working with the bare soil.
- Check the ground is even. Use a flat surface (a decking board or tamper is perfect for this) and place a spirit level on top to check the ground is even. If the spirit level indicates the ground is uneven, level it out with extra soil or compact the soil to flatten it out.
- Now here are your two options for laying your decking. You can either build it directly on the ground or square the site and build it on top of risers as a floating deck. If you lay it directly on the ground, you may find that it’s more susceptible to absorbing moisture and might need additional maintenance. If you’re laying your deck straight onto the ground, cover the area with a layer of weed control fabric. Then add 40 mm to 50 mm of gravel on top.
- The other method is to create concrete pads for the deck to sit on top of. This will reduce the likelihood of moisture seeping into the frame and causing damage. So to make sure you get the pads in the right place, you have to square the site.
- Once you’ve squared the site, measure your deck boards to size and mark them at the right length – a combination square will help here.
- Cut the board.
- Lay the decking on the grass in your decided design and leave the right expansion gaps between boards (5 to 8 mm along the length of boards, and 3 mm along the ends). This will show you if you have enough decking to complete the job. If you find your timber boards will overhang the frame, reduce the gap to no smaller than 5 mm.
- Measure the frame for your decking and cut to size. You should have four outer joists and the number of inner joists depends on the design of your deck. Horizontal deck boards should have joists a maximum of 350mm between the centre of one supporting joist and the centre of the next.
- Make two pencil marks on each end of the frame’s two outer joists; these are the joists that are at right angles to the frames inner joist. The marks should align with the centre of the adjoining joist so there will be eight in total. Two in each corner of the outer joist frame.
- Drill recesses into each mark with a flat wood drill bit. These should be the depth of the screw’s head and wide enough for a ratchet or socket attachment to tighten them. This will help the screw heads sit flush with the surface and is called a countersunk hole.
- Use a thinner drill bit to drill a pilot hole through the centre of the recess from the outer joist into the adjoining joist. This will guide the screws into the hole and will prevent the wood from splitting.
- Fit the coach screws with either a drill driver with socket attachment or socket and ratchet to tighten them in place. You might find it easier to do steps 11 to 13 on one corner at a time instead of all corners, step-by-step.
- You should now have a secure square frame. The next step is to add the inner joists which will evenly divide the square frame. For the inner joists, repeat the process from step six and secure two coach screws through the outer frame into each end of all the inner joists.