Trellis and Panel Fencing: Overlap, Lap and Decorative Panel Specification, Trellis Top Considerations

Quick Answer: UK panel fencing splits into overlap (cheap, ~£18–35 per 1.83×1.83m panel), lap (mid-tier, planed thin boards), close board (premium, factory-assembled feather edge) and decorative (slatted, hit-and-miss, woven, contemporary horizontal). Standard panel size is 1830mm × 1830mm to fit between concrete posts at 1.83m centres. Trellis tops add 300–600mm to a boundary fence and remain within permitted development to 2m total (1m near highway). All timber should be pressure-treated to BS 8417 Use Class 3 (above-ground). Lifetime: overlap panels 8–12 years, close board panels 15–20 years, trellis 7–12 years depending on exposure and treatment quality.

Summary

Panel fencing is the path of least resistance for most UK boundary work. Factory-made 1830×1830mm panels slot into concrete posts in an afternoon, no on-site rail-and-pale construction, no waste, predictable cost. The trade-off is per-panel lifespan: even good panels need replacement at 10–15 years, against 20–25 years for an in-situ close board fence. The advantage is that each replacement is a single-panel job with no foundation disturbance — drop a panel out, slot a new one in. Concrete posts and gravel boards remain in place for the life of the boundary.

Trellis is the decorative cousin — open lattice timber (or composite/metal) used as a fence-top extension, a free-standing screen, or a climbing plant support. Trellis on top of a 1.5m boundary fence is a common way to gain privacy without breaching the 2m permitted development height; it also softens a solid boundary visually.

This article covers panel and trellis specification, common materials, when each works, and the install detail. For overlap and close-board pales, see feather edge fencing installation. For supporting concrete posts, see concrete post gravel boards.

Key Facts

• Standard panel size — 1830mm × 1830mm (6ft × 6ft); panel widths from 0.9–2.4m available
• Lower heights — 0.6m, 0.9m, 1.2m, 1.5m, 1.83m panels stocked at most merchants
• Overlap panel — horizontal lapped boards on outside, two vertical battens, two top/bottom horizontal rails
• Lap panel — similar to overlap but with planed boards; cleaner finish
• Waney edge panel — natural curved edge on boards; rustic appearance
• Close board panel — pre-assembled feather edge pales on three rails; equivalent to in-situ build
• Decorative panels — slatted, hit-and-miss, woven willow, woven hazel, double-sided
• Trellis panel — square or diamond lattice from 25×25mm to 50×50mm openings; 300×1830mm to 600×1830mm sizes
• Pressure treatment — Tanalith E or Wolmanit CX; BS 8417 Use Class 3
• Panel weight — overlap 18–25 kg; close board 28–35 kg
• Service life — overlap 8–12 years, lap 10–14 years, close board panel 15–20 years, trellis 7–12 years
• Panel-to-post slot fitting — concrete posts have 36mm slot accepting standard panel thickness
• Maximum total boundary height — 2m (non-highway), 1m (highway-adjacent)
• Trellis top adds — typically 300–600mm; total still subject to 2m / 1m limits
• Treatment colour — golden brown (Tanalith), green-brown (older treatments)
• Stain compatibility — most pressure treatments are dyed; topcoat stain may show colour variation for 6–12 months
• Fixings — galvanised lost-head nails or stainless screws

Quick Reference Table

Detailed Guidance

Overlap vs lap vs close board — making the right call

Overlap panels are the cheapest factory-built panel — horizontal sawn boards lapped over each other, fixed to two vertical battens, with a top and bottom horizontal rail. They use thin (8–11mm) sawn boards and minimal framing. They are wind-flexible — boards bow visibly in gusts — and the lap joints open as the timber dries. Service life 8–12 years on a sheltered residential boundary; less on exposed sites.

Lap panels (planed lap) use planed boards rather than sawn; slightly cleaner finish, slightly longer life. Common for front-garden boundaries where the panel will be seen.

Close board panels are a factory-built version of in-situ close board — feather-edge pales on three arris rails, properly framed, capping rail. Service life 15–20 years. Cost is 2–3× overlap.

For a rear boundary on a sheltered residential plot, overlap is fine and the cost saving is meaningful. For a front-of-house boundary on an exposed site, close board is the right answer.

Decorative and contemporary styles

The garden-design market has expanded the panel category:

• Hit-and-miss — boards alternate inside and outside of the rails; wind-permeable; same view both sides; ~20% more timber than close board so longer life. Increasingly common for modern gardens.
• Slatted horizontal — square section timber slats running horizontally; gaps of 10–25mm between slats; very contemporary look. Common in urban gardens. Cost 2–4× close board.
• Slatted vertical — vertical version of the above; less common but used for screen walls and feature boundaries.
• Decorative top — scallop, curved, or arched tops on a standard panel; cottage / period aesthetic.
• Woven willow / hazel — natural, biodegradable, woven by hand; lasts 5–10 years; popular in cottage gardens.

For any of these decorative styles, manage the customer's life-expectancy expectation. Decorative timber rarely lasts as long as plain close board.

Trellis specification

Trellis comes in two main grades:

• Standard trellis — 25×25mm to 38×38mm timber laths in a 75mm or 100mm grid; pressure-treated; service life 7–12 years
• Premium trellis — heavier section laths (38×38mm to 50×50mm), tighter grid, often double-thickness intersections; service life 12–18 years

Common sizes:

• 300mm × 1830mm — top extension
• 600mm × 1830mm — taller top extension or screen
• 900mm × 1830mm — half-height fence
• 1830mm × 1830mm — full-height fence (rare)

Trellis is not a structural panel; it does not hold its own weight at full-height unless supported by strong posts and bracing.

Combining trellis with solid panels

The common configuration:

• 1.5m close board or lap panel at the base
• 300mm trellis on top
• Total height: 1.8m (within permitted development for non-highway boundary)

Or:

• 1.2m solid + 600mm trellis = 1.8m
• 0.9m solid + 900mm trellis = 1.8m

The trellis offers visual softening, planting opportunity (clematis, jasmine, climbing roses), and continues the boundary line at full height. Without trellis, the 1.2m or 1.5m solid panel feels low; with trellis, it feels like a proper boundary.

Fixing: trellis sits in the top of the post slot, supported by the post and screwed to a small batten across the panel top. Some panel manufacturers supply trellis-topped panels as a single unit.

Installing panel fencing

Sequence:

1. Set concrete posts at 1.83m centres on the fence line; see concrete post gravel boards
2. Slide concrete gravel boards into the slots between adjacent posts
3. Slide the panel down into the post slots, sitting on the gravel board
4. Repeat across the run; close in with corner or end post detail
5. For trellis-topped fences, slide the trellis section in last
6. Cap any cut edges with proprietary slot covers or timber

Slot tolerance: panels are typically 1830mm wide; slot-to-slot distance 1832mm leaving ~2mm tolerance. Concrete posts must be set accurately to allow panels to drop in without forcing.

Repair: replacing a single panel

The advantage of panel-and-concrete-post systems: replacing a damaged panel is a 30-minute job.

• Slide damaged panel up out of the slots
• Inspect gravel board and posts
• Slide new panel into the slots
• No tools required for the lift itself; help may be needed for 25–35 kg panels

This is why panel fencing is the long-term value choice over in-situ close board for most boundary work. Net annual cost is lower than the upfront cost difference suggests.

Decorative considerations and weathering

Pressure-treated panels weather to silver-grey within 12–18 months. Staining options:

• Cuprinol Garden Shades (opaque) — colour-fast, hides timber grain; recoat 3–4 years
• Sadolin / Sikkens (translucent) — shows grain; recoat 2–3 years
• Ronseal (range of fence-care products) — moderate quality; recoat 2 years

For a maintenance-light boundary, leave the timber bare and accept the silver weathering. For a decorative front-garden boundary, plan on staining every 2–3 years.

Wind exposure and panel selection

Solid panels (overlap, lap, close board) behave like a wall in wind — full load transfer to the posts. Hit-and-miss and slatted panels are wind-permeable and put less load on the substructure.

For exposed sites (coastal, hilltop, open country):

• Prefer hit-and-miss or slatted; the panel itself flexes less
• Use heavier concrete posts (125×125mm rather than 100×100mm)
• Increase post depth (see fence post installation depth)
• Consider a row of robust planting on the windward side to break the wind

Frequently Asked Questions

How long do fence panels last?

Overlap: 8–12 years. Lap: 10–14 years. Close board: 15–20 years. Trellis: 7–12 years. All assume pressure-treated UC3 timber and reasonable site conditions. Coastal, hilltop and damp sites reduce these figures.

Can I install panels on timber posts instead of concrete?

Yes, but plan for shorter system life. Timber posts last 15–25 years; panels rotate down as posts settle. Concrete posts give 40+ year boundary life and stable panel slot dimensions.

What's the difference between overlap and lap?

Overlap uses sawn boards (rough surface, slightly bowed); lap uses planed boards (smooth). The framing and assembly are similar; lap looks better and lasts slightly longer.

Are trellis tops counted in the 2m height limit?

Yes — total height from ground to top of trellis must be within the permitted development limit (2m for non-highway boundary, 1m where adjacent to highway). Some Local Authorities are pragmatic about open trellis but officially it counts.

What size are standard fence panels?

The UK standard is 1830mm × 1830mm (6ft × 6ft). Other widths and heights available: panels go from 0.6m to 1.83m wide, and 0.6m to 2.4m tall. Special sizes (often used for tapering panels on a slope) are available at higher cost.

Can I cut a panel down to fit?

Yes for overlap, lap and close board panels — saw to width, re-fix the end batten. For decorative slatted panels, cutting often spoils the look. Best practice: order the right-size panel.

Will horse / livestock-grade panels work for residential?

They tend to be over-engineered (and over-priced) for residential use. The pales and rails are heavier; the framing more robust. If aesthetic doesn't matter and the customer wants maximum durability, livestock-grade is an option. Otherwise standard residential close board is more cost-effective.

Regulations & Standards

• BS 1722-1 to -14 — Fences specification (multiple parts covering different fence types)

• BS 1722-5 — Close-boarded fences and palisades

• BS 8417 — Preservation of wood — Code of practice (Use Classes)

• BS EN 350 — Durability of wood

• BS EN 351 — Durability of wood treated with preservatives

• BS EN 12839 — Precast concrete products — fence elements

• Town and Country Planning Order 2015 — Class A Schedule 2 (height limits for boundaries)

• Wildlife and Countryside Act 1981 — relevant for hedge replacement during nesting season

• CDM Regulations 2015 — applies to commercial fencing projects

• Planning Portal — Fences and gates — UK height limits

• BSI — BS 1722 series — fence specification standards

• Wood Protection Association — Use Classes guidance

• TRADA — Timber Fence Specification — design and detail

• Jacksons Fencing — Technical guidance — manufacturer specification reference

• feather edge fencing installation — close board pales in factory panels

• concrete post gravel boards — substrate for panel systems

• fence post installation depth — post foundation specification

• timber close board fencing — in-situ close board vs factory panel

• planning permission fences walls — height limits and consents