How to Build a Fence: A Complete Step-by-Step Guide
A well-built fence will last 20 years or more. A poorly built one will be leaning within two winters. The difference almost always comes down to the posts — get those right and everything else follows naturally. Get them wrong and no amount of quality fencing board will save you.
This guide takes you through the whole process from planning to finishing, whether you're replacing an existing fence or putting one up for the first time.
Before You Start — Planning and Permissions
Check your boundaries. Before you dig a single hole, be clear on where your boundary actually is. If you're in any doubt, check your title deeds or speak to your neighbour. A fence built on the wrong side of a boundary line is an expensive mistake.
Check permitted development rules. In most cases a garden fence under 2 metres high doesn't need planning permission. However, if your property is on a corner plot, in a conservation area, or the fence would be adjacent to a highway, different rules may apply. Check with your local planning authority if you're unsure.
Talk to your neighbours. Even where you have the right to put up a fence, it's good practice to let your neighbour know, particularly if the new fence will affect light or views. It avoids disputes later and keeps things neighbourly.
Mark the line. Use a string line and pegs to mark the fence line precisely before you start. This is the most important prep step — a straight fence looks professional, a wandering one doesn't.
What You'll Need
Timber:
- Fence posts — 100mm x 100mm UC4 brown treated posts are the standard for a domestic fence. For a 1.8m high fence, use 2.4m posts (600mm in the ground, 1.8m above). For a 1.5m fence, use 2.1m posts
- Featheredge boards — the most common fencing board in the UK. Available in 1.2m, 1.5m, 1.8m heights. We stock both brown treated and green treated
- Arris rails — the horizontal rails that the featheredge boards fix to. For a 1.8m fence, use three rails; for 1.5m, two rails are usually sufficient
- Gravel boards — 150mm x 22mm boards that sit at the base of the fence between posts, keeping the featheredge boards off the ground and significantly extending their life
Fixings and materials:
- Postcrete or concrete — Postcrete (post mix) is the quickest option for domestic fencing. One 20kg bag per post is usually sufficient for a 100mm post
- Galvanised nails — 65mm round wire nails for fixing featheredge boards to arris rails
- Arris rail brackets — galvanised brackets for fixing arris rails to posts
- Gravel board clips — for fixing gravel boards to posts
Tools:
- Post hole borer or spade
- Spirit level
- String line and pegs
- Hammer or nail gun
- Tape measure
- Saw
- Bucket and water for Postcrete
We stock everything you need — view our full fencing range including featheredge boards, fence posts, arris rails, gravel boards, and Postcrete.
How Much Fencing Do You Need?
Posts — space posts at 1.83m (6 foot) centres. Divide your total fence length by 1.83 and add 1 for the final post. Round up to the nearest whole number.
For example, a 15m fence run: 15 ÷ 1.83 = 8.2, plus 1 = 9.2, so you need 10 posts.
Featheredge boards — each board covers approximately 100mm (4 inches) of width when overlapped correctly. For a 1.83m bay, you need approximately 17–18 boards per bay.
For a 15m fence: 8 bays x 18 boards = 144 boards. Always add 10% for waste — so order 160 boards.
Arris rails — for a 1.83m post spacing with three rails per bay: 8 bays x 3 = 24 arris rails.
Gravel boards — one per bay. 8 bays = 8 gravel boards.
Postcrete — one 20kg bag per post. 10 posts = 10 bags.
If you give us your total fence length and height we'll calculate everything for you — call us on 01452 300159.
Step 1 — Set Out the Posts
This is the most critical part of the whole job. Take your time here.
Run your string line along the fence line from end to end, pulled tight and at the height of the top of the finished fence. Mark post positions at 1.83m centres along the string with a cane or spray paint on the ground.
Dig or bore your post holes to the correct depth — for a 1.8m fence using 2.4m posts, you need 600mm depth (one third of the post length in the ground is the standard rule). Make the hole as narrow as practically possible — a tight hole with Postcrete gives a much stronger result than a wide sloppy one.
Drop the post in, pack around the base with a handful of hardcore or gravel for drainage, then mix and pour your Postcrete following the bag instructions. Most post mix products just need water poured in — no mixing required.
Check the post is plumb in both directions with a spirit level, brace it if needed, and leave it for at least 24 hours before loading it with rails and boards. Don't rush this stage.
Work from one end to the other, checking each post against your string line for alignment and against your spirit level for plumb. Small errors compound quickly along a long run.
Step 2 — Fit the Arris Rails
Once your posts have set, fit the arris rails. The standard position for a three-rail 1.8m fence is:
- Bottom rail — 150mm up from the ground (sits above the gravel board)
- Middle rail — approximately 900mm from the ground
- Top rail — approximately 75mm down from the top of the fence
Use galvanised arris rail brackets to fix the rails to the posts. Slot the pointed end of the arris rail into the bracket and nail through the bracket into the post. Check each rail is level before fixing.
If you need to join arris rails mid-span, always make the join at a post — never in the middle of a bay where it will have no support.
Step 3 — Fit the Gravel Boards
Fit gravel boards between the posts at ground level before you start on the featheredge boards. They should sit flat on the ground (or just above if the ground is very uneven) between the posts.
Fix with gravel board clips nailed to the posts on each side. The gravel board keeps the featheredge boards off the ground, which is the single most effective thing you can do to extend the life of your fence. Ground contact rots even treated timber quickly — gravel boards sacrifice themselves instead, and they're cheap and easy to replace.
Step 4 — Fix the Featheredge Boards
Start at one end and work along the fence. The thick edge of the featheredge board always goes to the left (or right — be consistent throughout), with the thin edge overlapping the thick edge of the previous board by approximately 25mm.
Fix each board to each arris rail with a single 65mm galvanised nail through the thick edge — two nails risks splitting. Work along checking with a spirit level every few boards to make sure you're running plumb. It's easy to drift slightly and end up with boards that visibly lean by the time you reach the other end.
At posts, cut boards to fit neatly. A sharp saw and a square cut make all the difference to the finished look.
The top of the boards should sit approximately 50mm above the top arris rail for a tidy finish.
Step 5 — Fit the Post Caps
Fit post caps to all posts when the boards are done. They keep water out of the end grain of the post — which is where rot starts — and give the fence a neat, finished look. Simple pyramid or flat caps in treated timber are inexpensive and make a real difference to longevity.
Step 6 — Treatment
If you're using pre-treated featheredge (which all our stock is), the boards are already protected. However, treat all cut ends with an end-grain preservative immediately after cutting — the saw exposes untreated timber and this is where moisture will get in.
A full coat of fence paint or treatment applied after construction is optional but worthwhile. Brown or black fence paint applied with a brush or roller will top up the protection and keep the fence looking smart for years.
We stock a range of landscaping treatments suitable for both treated and untreated fencing timber.
Common Mistakes to Avoid
Posts not deep enough — the number one cause of fence failure. Always go to at least one third of the total post length in the ground. For a 1.8m fence, 600mm minimum.
Posts set in concrete all the way to the surface — always finish the concrete slightly below ground level and back-fill with soil. This prevents water pooling at the base of the post where it enters the concrete, which accelerates rot.
Skipping the gravel board — saves money upfront, costs far more in premature fence replacement. Always use them.
Not treating cut ends — takes two minutes and significantly extends the life of every board.
Fixing boards in wet weather — wet timber will shrink as it dries, leaving visible gaps. Where possible, fix boards in dry conditions.
Using ungalvanised nails — they'll rust within two or three years, staining the boards and losing their grip. Always use galvanised or stainless steel fixings.
How Long Will It Last?
A well-built fence using properly treated timber, with posts set correctly in concrete and gravel boards fitted, should last 15–20 years before requiring significant maintenance. The posts will typically be the first component to need replacing — which is why setting them correctly in the first place is so important.
Annual maintenance is straightforward — check post bases for movement in early spring, replace any boards that have split or warped, and apply a fresh coat of treatment every two or three years.
Ready to Order Your Fencing Materials?
We stock a comprehensive range of fencing timber and fixings at our Gloucester depot, with free delivery on orders over £750 + VAT within 75 miles. We deliver to Cheltenham, Bristol, Stroud, Tewkesbury, Swindon, Hereford, Oxford, and across Gloucestershire and the South West.
- Featheredge fencing boards
- Fence posts — 100mm x 100mm treated
- Arris rails and capping
- Gravel boards
- Postcrete post mix
- All fencing supplies
Call us on 01452 300159 to discuss your project or get a quantity calculation — we're happy to work through the materials list with you to make sure you order exactly what you need, first time.
Nick's Timber Store, Canada Wharf, Bristol Road, Gloucester GL1 5TE. Rated 4.9/5 on Trustpilot from over 96 reviews.
