Step 1 Demolish old fence, if needed. Using post hole digger, dig 600mm-deep hole at end of fence. Mix up concrete in wheelbarrow and pour small amount into bottom of hole. Join 1 square post to 1 standard post, make flush at 1 end and screw together. Place post assembly in hole, so top is 1850mm above ground, ensuring plumb. Fill hole with concrete, tapering top of concrete away from assembly. Repeat for other end of fence.
Step 2 Run stringline between end post assemblies and make taut. Starting from 1 end, lay down bottom rails along length. By doing this, you won’t need to measure for each post hole. Mark ground at each join, before digging each post hole to a minimum depth of 600mm.
Step 3 For all posts along fence, you’ll need to also create a double-sided post (post assembly). Do this by placing 2 standard posts back to back, and screwing them together with 16mm self-tapping screws. Fix 2 screws 100mm from top and space the remaining screws every 350mm, staggering them along the post.
Step 4 For a stepped fence, as here, you will need to offset height of posts from 1 panel to next. To work out by how much, place a bottom rail in U-channel of end post, so it is 50mm above ground. Screw through both sides of the end post into rail to secure. Level rail. Measure distance to ground at other end. Deduct 50mm to find how much height of posts will differ.
Step 5 Place post assembly in hole and make it meet stringline. Slide bottom rail into higher side of post at the correct height and fix with self-tapping screws. Loosely lay top rail between 2 posts to get right spacing at top. Make post plumb and bottom rail level. Concrete in position. Check it is on stringline and still plumb. Repeat for following posts and leave concrete to set.
Step 6 To install infill sheets, slide top rail into fence post at correct height and fix at 1 end. Towards middle of a panel, sit sheet in bottom rail, then lift top rail and slide sheet into it. Ease sheet along panel until it slots into post. Insert second sheet and slide along, so it overlaps first. Finish with final panel that overlaps second and slots into fence post. Secure other end of top rail. Repeat for all panels. Use tin snips to cut an infill sheet along its length for shortened panels.
Step 7 If you have an existing garden bed, use a shovel to dig in soil, then mulch before planting up. For new beds, remove turf with a shovel and dig in soil, then mulch. Plant up with selection of plants and water in well.