Fence Panels: Reinstating the Boundary After Your Extension

The scaffolders knocked two panels down when they struck the rig. Your neighbour wants to know when it's being fixed. The builder says fencing isn't his problem. You assumed it was, because everything on your side of the build is your problem.

This is where most kitchen extension budgets quietly leak. Fence reinstatement is almost never itemised in the builder's quote, the neighbour never forgets, and the cost varies by a factor of four depending on which panel you pick. Get the decision right once, at the right point in the build, and it's a £500 line item. Get it wrong and you're back out there in three years with another pallet of panels and a harder conversation.

What a fence panel actually is

A fence panel is a prefabricated timber (or composite) section that slots or screws between upright posts to form a boundary. The standard UK width is 1.83 metres (6 feet), which maps to the slot spacing on standard concrete posts and the available widths from every UK manufacturer. Heights run from 900mm (3ft) through 1.2m (4ft) and 1.5m (5ft) to 1.8m (6ft), with the 1.8m panel the default for rear and side boundaries on a UK residential plot.

The panel doesn't stand on its own. A typical timber fence run is three parts: panel, post, and gravel board. The post carries the structural load and anchors into the ground. The gravel board (a 140-150mm deep concrete or timber board) sits under the panel and lifts it clear of the soil. The panel fills the gap in between and does the visual work.

That three-part anatomy is why swapping a single broken panel isn't always easy. If your posts are concrete with slots, a panel slides out vertically. If your posts are timber and the panel was nailed or screwed, you're levering the old one off and hoping the post holds. The post-damage scenario (rotten or split post) turns a £40 panel swap into a full panel-post-gravel-board replacement.

Planning rules: the 2-metre line you must not cross

Before you order anything, check the height. The General Permitted Development Order 2015 (Schedule 2, Part 2, Class A) sets two hard ceilings on fence height without planning permission:

• 2 metres maximum in all other locations
• 1 metre maximum where the fence sits adjacent to a highway used by vehicular traffic (and next to the pedestrian footway that abuts it)

Measure from the natural ground level on the lower side of the fence. A 1.8m panel on top of a 150mm gravel board is 1.95m, under the 2m limit. Add a 300mm trellis topper to the same panel and you're at 2.25m. That needs planning permission, and the local planning authority will enforce it if a neighbour complains.

Conservation areas, Article 4 directions, and listed buildings override permitted development entirely. Check your local planning authority's online map before ordering. The £48 check is cheaper than taking a fence down.

Scotland and Wales run the same 2m general and 1m highway-adjacent rules. Wales adds one wrinkle: in conservation areas, you need conservation area consent to remove an existing fence, not just to erect a new one. Northern Ireland broadly aligns. The front-of-house rule across all four nations: anything forward of the principal elevation facing a highway drops to the 1m cap.

Who owns the fence

No legal default says the left fence is yours and the right is the neighbour's. There isn't one. What exists is the title plan on the HM Land Registry record, which sometimes shows T-marks indicating boundary ownership: the T points into the garden of the owner. An H-mark (two Ts back to back) means shared responsibility.

T-marks only have legal force if the deed text explicitly references them. Many properties have no marks at all, or marks that are purely indicative. Before you spend a penny on replacement panels, pull your title plan from the Land Registry (£3 for the register, £3 for the title plan) and read the accompanying deed text. If there's a T-mark and the deed references it, ownership is clear. If not, ownership follows whoever has maintained the fence historically, or a genuine ambiguity you need to resolve with the neighbour in writing before work starts.

The "good side faces the neighbour" rule is convention, not law. There's no legal requirement to orient the decorative face outward. Following the convention buys goodwill and prevents the neighbour from complaining to the council that your fence is "backwards". Breaking it is legal but costs you the relationship.

Types of panel: the only comparison that matters

Take the lap panel first because it's what you'll see stacked at every B&Q and Wickes at the front of the fencing aisle. It's made from thin horizontal timber boards (8-12mm) overlapped and pinned to a simple softwood frame. The frame is the weak point. Lap panels flex in wind because the frame is light. They fail because the pin-nails rust, the boards loosen, and the whole panel racks out of square. In a sheltered back garden, a dip-treated lap panel lasts about seven years. On an exposed corner plot, closer to four.

Dip-treated means the timber was dunked in preservative. The treatment sits on the surface. Pressure-treated means the preservative was forced into the wood cells under vacuum and pressure in a sealed chamber. Pressure-treated panels need no retreatment; dip-treated panels need a fresh coat of preservative every one to two years to stay within warranty and resist rot. Every time you see a price gap of £8-10 between two otherwise identical lap panels at Wickes, that gap is the treatment difference.

Closeboard is the step up most builders will quote for a proper boundary. It's built differently: vertical feather-edge boards nailed to horizontal backing rails, with a capping rail on top. The result is much stiffer than a lap panel. The feather-edge profile sheds water. Closeboard panels last 15-25 years when pressure-treated, and the Jakcure variant runs to a 25-year manufacturer guarantee with annual retreatment not required. If you're reinstating a boundary once and don't want to think about it again for 20 years, closeboard is the default answer.

Hit-and-miss is the sleeper choice for exposed sites. Alternating vertical boards on either side of the frame leave roughly 50% of the face open to wind, which means the fence can't be blown over because there's nothing for the wind to push against. On a boundary that lost panels in a gale, hit-and-miss is the fix. It's also the panel that's quietly taking over contemporary gardens because the pattern looks architectural rather than suburban.

Composite panels are wood-plastic composite boards fitted into aluminium channels on an aluminium post system (DuraPost and similar). They don't rot, don't need painting, and last 25+ years. They cost two to three times what timber costs up front. Over 20 years the maths roughly evens out when you factor in the two-year retreatment cycle on timber, but the up-front cost keeps most homeowners on timber. One warning: cheap composite imports split in severe wind. Buy from a reputable composite supplier or don't buy composite.

Click to enlarge

Gravel boards: the 150mm that doubles your panel's life

A gravel board is a 140-150mm deep horizontal board that sits under the fence panel, between the two posts, at ground level. Its only job is to stop the panel touching the soil. Soil holds moisture. Moisture wicks up through timber. A panel in direct soil contact will rot at the base within five years regardless of treatment grade. The same panel with a gravel board underneath routinely lasts the full 15-25 years of its stated lifespan.

Concrete gravel boards cost £15-25 each at 1.83m length. Timber gravel boards cost £8-15. Concrete is the right choice for every permanent installation. It doesn't rot, it resists strimmer damage, and when the panel above eventually needs replacing, the gravel board stays. Timber gravel boards are a false economy, they rot at the same rate as the panel they were meant to protect.

Gravel boards are often a warranty condition on pressure-treated panels from quality suppliers. Our position is simpler: always fit gravel boards. The £15 per metre of boundary saves £60 of panel five years earlier than you'd otherwise replace.

Posts: the decision that matters more than the panel

Post choice determines how easy future panel replacement will be. There are three common systems.

Concrete slotted posts have two vertical slots moulded into the post to accept the edges of the panel. You slide the panel in from above and it holds by gravity and friction. When a panel rots or gets storm-damaged, you slide the damaged panel out and slide the new one in. Concrete posts last 25+ years and need zero maintenance. They're heavy (40kg+ for a 2.4m post) and less pretty than timber. Most UK rear-garden fencing uses concrete slotted posts because of the slide-in-slide-out advantage.

Timber posts (UC4 pressure-treated, 100mm x 100mm) get concreted into the ground, and the panel is either screwed directly to the post or held in place with fixing brackets. Timber posts last 10-15 years even when pressure-treated, because the section at the soil-air interface rots from the inside. When the post goes, the panels come with it. Timber posts look more natural than concrete and are lighter to install, but every post you use is a future failure point.

Metal post spikes (Metpost or similar) drive into the ground and accept a 75mm or 100mm timber post in a metal collar. Sold as the DIY-friendly option, they're the least durable of the three. Spikes rock in the ground under wind load and panels lift out within five years. Avoid for permanent installations.

Post spacing centres at 1.83m match the panel width exactly. Out-of-the-box posts come at 2.4m (for a 1.8m panel above ground plus 600mm in the ground) or 3.0m (where exposed conditions warrant deeper setting). A 2.4m post concreted to 600mm depth is the standard domestic spec. Exposed coastal or hilltop sites want 750-900mm depth with 3.0m posts, which also means wider holes and more postcrete per post.

For the full post decision covered properly, see the fence post page.

How many panels, posts, and gravel boards do you need

The calculation is simple and the arithmetic catches people out.

Panels = boundary length ÷ 1.83m, rounded up

Posts = panels + 1 (you need a post at each end and between every pair of panels)

Gravel boards = panels (one under each panel)

Worked example: a 15m rear boundary after a single-storey rear extension.

• Panels: 15 ÷ 1.83 = 8.2, round up to 9 panels
• Posts: 9 + 1 = 10 posts
• Gravel boards: 9 boards
• Postcrete: budget 2 x 20kg bags per post = 20 bags

The last panel at the end of the run almost always needs cutting down. Buy the full 9 panels, not 8, and cut the last one to fit. If your boundary length is over 15m and runs into a neighbour's corner post, your panel count might reduce by one because you borrow their existing post. Confirm before ordering.

Wastage allowance: 0% on panels (you order exact and cut the last one), 5% on postcrete (one extra bag per pallet in case of a wet hole or a deeper-than-expected post).

What it costs, supply-only

Dip-treated overlap panels at 6ft x 6ft run £29-37 at Wickes and B&Q in April 2026. Pressure-treated overlap at the same dimensions runs £37-45. Both prices are before delivery; big-box merchants typically charge £30-50 for a flatbed delivery unless you collect.

Dip-treated closeboard 6x6 at Wickes is £68 each. Pressure-treated closeboard runs £83-90 direct or £80-90 through retail merchants. Pressure-treated closeboard with a 25-year guaranteed treatment through specialist stockists is £71-80 including VAT, which is exceptional value for long-term boundaries.

Hit-and-miss panels sit in a wide band of £65-130 depending on brand and treatment grade. Budget hit-and-miss from regional suppliers (often dip-treated) starts at £65.

Composite panels are the outlier. Supply-only costs run £117-200 per panel depending on brand and board pattern. Quality composite suppliers sit at the top of that band; imported budget composite at the bottom (buy with caution).

What it costs supply and install

If you're having a fencing contractor do the job, the supply-and-install rates that matter:

• Lap/overlap, timber posts: £60-90 per metre installed
• Closeboard, concrete posts: £100-150 per metre installed
• Hit-and-miss, concrete posts: £110-140 per metre installed
• Composite on aluminium post system: £85-150 per metre installed

A 15m boundary in pressure-treated closeboard on concrete slotted posts with concrete gravel boards, professionally installed, runs £1,500-£2,250 all-in. The same boundary in dip-treated lap panels on timber posts with timber gravel boards runs £900-£1,350, saves you £600 up-front, and has you back on the phone to the fencing contractor in seven years.

Labour per panel runs £50-80. Fencing contractors typically price at £300-400 per day and put up 5-7 panels per day including posts. Old fence removal, when the neighbour's fence needs clearing first, adds about £35 per panel to the quote.

Post-extension timing: when to actually do it

Fence reinstatement goes last in the external works sequence. The order on a post-extension site:

1. Scaffold strike and removal
2. Builder's site clearance and skip collection
3. Groundwork reinstatement (topsoil replaced over any disturbed ground)
4. Patio or paving installation
5. Fence reinstatement
6. Turf or planting

Don't let the builder reinstate the fence before the scaffold goes. Scaffold lorries, skip lorries, and material deliveries damage fences a second time. The correct sequence is: photograph the damage before any work starts, agree the fencing line with the neighbour in writing, reinstate after the last skip leaves.

Talking to the neighbour

Fence replacement after an extension is the highest-risk neighbour moment in the whole build. They've watched scaffold go up, listened to six months of drilling, lost use of their garden for half a summer, and now their fence is damaged. This is when the relationship either recovers or becomes permanent.

Three rules, in order of priority.

Notify, don't ask. If the fence is yours (per the title plan), you don't need the neighbour's permission to replace it. Asking sets up a scenario where they can say no and you're stuck. Telling them politely, in writing, what you're doing and when, keeps the decision with you and the information flow with them.

Offer to split the cost, even when you don't have to. If the extension build caused the damage, the fencing is part of your reinstatement obligation and the neighbour owes nothing. If the fence was old and you're upgrading, a 50/50 split on the cost difference between a like-for-like replacement and the upgrade is the conventional goodwill offer. Forum threads on MoneySavingExpert confirm this as the reliable social norm after extension work.

Good side to the neighbour. Convention says the decorative face of the panel (the smooth side on closeboard, the flat side on lap) faces outward toward the neighbour. You see the rails and fixings. This costs you nothing and buys significant goodwill. There's no legal requirement, so this is entirely a relationship decision.

Put the agreement in writing before work starts. A short letter or email confirming: fence ownership per Land Registry, planned replacement date, panel type and height, good-side orientation, expected duration. The paper trail prevents every common dispute (wrong height, wrong side, wrong date, wrong cost share).

Alternatives to a standard panel fence

Masonry wall. A 1.8m brick or block boundary wall costs £250-450 per metre built but lasts 80+ years and needs zero maintenance. Over a 30-year window it's often cheaper than two fence replacement cycles. Planning limits are identical (2m general, 1m highway-adjacent). Consider for front boundaries and where the extension's external finish is brick.

Hedging. A beech or privet hedge costs £5-15 per plant at 3-4 plants per metre and grows to mature height in 4-6 years. Almost no maintenance beyond annual trimming once established. Doesn't work next to a patio (root spread) or where neighbour privacy is needed immediately.

Trellis and climbers only. Where a wall or fence already exists, extending height with a trellis panel (up to the 2m planning limit) plus climbing plants costs £40-70 per metre and softens the visual weight of a solid panel run.

Where you'll need this

• Fence post, the post system determines installation method, replacement effort, and long-term durability as much as the panel choice does
• Paving slabs, fence line and patio edge interact; install the patio before the fence so the panel base sits clear of the paving edge
• Topsoil, reinstated soil at the fence line affects post-setting depth and moisture exposure at the panel base

These materials appear in the external works and completion phase of any extension or renovation project where a boundary was damaged or needs upgrading alongside the new build.

Common mistakes

Lap panels on an exposed site. The single most common failure mode. Lap flexes, pin-nails work loose, the frame racks, and a winter gale takes the panel out. On any boundary facing open ground, a prevailing wind corridor, or a narrow gap between buildings that funnels wind, use hit-and-miss or closeboard. Not lap.

No gravel board. Panels laid directly onto soil rot at the base within 3-5 years regardless of treatment grade. The £15 concrete gravel board per metre is the cheapest insurance on any fence installation.

Buying dip-treated when you wanted pressure-treated. Wickes and B&Q stock both on adjacent pallets with labels that aren't always obvious. Dip-treated lasts 5-10 years and needs annual retreatment. Pressure-treated lasts 15+ years with no retreatment. The price gap is usually £8-12 per panel. Always check the label.

Reinstating the fence before the scaffold is down. Your £2,000 new fence gets a scaffold pole dropped through it the first week. Reinstate after the last skip leaves. Not before.

Measuring from the high side of a sloped boundary. The 2m planning limit is measured from the natural ground level on the lower side of the fence. On a sloped boundary, measuring from the high side gives you a 2m fence that's actually 2.3m from the neighbour's view and potentially over the planning limit. Measure from the lower ground.

Forgetting the highway-adjacent 1m rule at the front. A common mistake on corner plots where the side garden runs along a road. Anything adjacent to a vehicular highway caps at 1m. Full stop. Not 1.2m, not 1.5m. Plan the front and side boundary height before ordering a pallet of 1.8m panels.