Inspired by a helpful YouTube guide. We based this walk-through on the Gosforth Handyman video "DIY Garden Fence Made With Decking Final Version", which documents the complete build on a real UK garden, including all the decisions around post condition, board spacing, and finishing. A thorough watch before you start is worthwhile.
1. Check the posts first
Before removing a single panel, work along every post and push it firmly. Any noticeable movement means the post is either rotten at the base or was not set deep enough. Replacing a post once the boards are on is a frustrating job. Sort it out now.
If posts are sound and set in concrete, they can stay. If any need replacing, dig or break out the old concrete, set new 100mm x 100mm posts in fresh postcrete to at least 600mm depth, and brace them until set - usually 24 to 48 hours.
2. Remove the old panels
Lap panels typically slot into grooved timber posts or clip into metal post brackets. Once identified, they usually lift straight out. Concrete-slotted posts just let the panel drop clear. Stack the old panels for disposal - if they're treated timber, most local tips have a specific skip for them, so check before loading the car.
3. Decide on board orientation and spacing
Horizontal boards are the most common choice for this style of fence. A 10 to 15mm gap between each board is typical - enough for airflow to prevent moisture build-up while still giving good privacy. Closing the boards tight against each other causes issues: moisture cannot escape, the wood swells, and boards eventually cup or split.
Decide on board width before ordering. 145mm boards give a clean look and require fewer fixings than narrower 95mm boards on a standard 1.8m fence height.
4. Fix the first board at the bottom
Start at the bottom and work upwards. Fix each board to the posts with two stainless steel screws per post - one near the top edge of the board, one near the bottom. Do not use galvanised screws if you can avoid it; they rust and leave brown streaks on the timber within a few years. The cost difference per box is negligible.
The bottom board should sit off the ground - at least 50mm clearance between the lowest board and the soil level. Boards touching the ground rot quickly, regardless of the preservative treatment.
5. Keep spacing consistent as you work up
Cut a simple timber spacer from an offcut - the exact gap you want between boards. Drop it on top of the last fixed board, rest the next board on it, and screw off. This is much faster and more accurate than measuring each gap individually. Check level with a spirit level every four or five boards; a small lean accumulates over a long run of fence.
6. Fit the top rail and cap the posts
A top rail of similar timber ties the fence together and protects the top edges of the uppermost board. Fix it flat across the tops of all the boards and screw down through it into each board. Cap the post tops with timber or metal post caps. Water sitting on end grain is the main reason posts rot - cap them and they will last much longer.
7. Apply a preservative stain
Pressure-treated timber is pre-treated against rot, but a preservative stain or oil adds colour, improves water runoff, and extends the life further. Apply one or two coats at the start and reapply every two to three years. Work the stain into the board ends and any cut surfaces thoroughly, as cut ends are where moisture enters most readily.
When to call a handyman
If posts need replacing, that is often the part where a DIY fence job stalls - breaking out old concrete and setting new posts in the right positions takes time and some effort. Richard can do the post work, the full fence replacement, or just advise if you want to tackle the boards yourself.
Need a fence replaced or updated?
The Sandwich Handyman can take down old panels, replace rotten posts, and build a new horizontal decking fence that lasts. Garden fencing work in Sandwich and nearby East Kent.
Contact Richard