- The Lunawood triple shadow gap is available in two sizes — 26x92mm and 32x140mm — each suited to different project scales and design intentions.
- It is produced from thermally modified Nordic pine by Lunawood — one of the world's leading ThermoWood manufacturers — with a BRE-accredited 30-year service life.
- The profile can be installed horizontally or vertically, over a ventilated batten framework, using visible screws or hidden fixings.
- No chemical preservative treatment required — left untreated it weathers naturally to silver-grey, or maintain with a UV oil every 3–5 years.
- Available from UK stock with nationwide delivery in 7–14 days — contact us for a precise quote and quantity calculation.
The Lunawood triple shadow gap is one of the most recognisable and widely specified exterior timber cladding profiles in UK architecture. Its three precisely machined shadow grooves create a distinctive horizontal rhythm that has defined the facade of hundreds of contemporary UK residential and commercial buildings — from house extensions and garden offices to schools, commercial units, and architect-designed new builds. This guide covers everything you need to know about the profile — from the technical specification and size options to installation details, finishing, and where to buy in the UK from stock.
We stock both sizes of the Lunawood triple shadow gap — 26x92mm and 32x140mm — for immediate delivery across the UK. All stock is PEFC certified ThermoWood pine from Lunawood's Finnish production facility. This guide will help you choose the right size, understand the installation requirements, and specify correctly for your project.
What Is the Lunawood Triple Shadow Gap Profile?
The Lunawood triple shadow gap close-up — three precisely machined shadow grooves create a refined horizontal rhythm across each board face.
A shadow gap cladding profile where three recessed grooves are machined across the face of each board. The grooves are designed to create shadow lines when the boards are installed — the recesses catch and hold shadow at different times of day, giving the facade a changing, three-dimensional quality that flat-faced boards cannot achieve. The triple shadow gap creates three shadow lines per board, producing a finer, more frequent pattern than single or double shadow gap profiles. When installed horizontally, the effect is a strong, precise horizontal rhythm across the full facade.
The Lunawood triple shadow gap is produced from thermally modified Nordic pine (Pinus sylvestris) — Lunawood Thermo Pine — using only heat and steam without chemical treatment. The boards have a uniform honey-brown colour when fresh and weather gradually to a consistent silver-grey when left unfinished. The precise machining of the shadow grooves is a hallmark of Lunawood's production process — the groove dimensions are held to tight tolerances across every batch, ensuring consistent shadow line depth and spacing from board to board.
The profile is used on external facades in UK residential, commercial, and public building projects. It is also suitable for interior feature wall applications — including saunas where the tongue and groove variation is more common — and for soffit and canopy cladding. For a full overview of all Lunawood profiles available in the UK, see our Lunawood ThermoWood cladding UK guide.
26x92mm vs 32x140mm — Which Size Should You Choose?
Lunawood triple shadow gap installed horizontally — the interplay of shadow and light across the groove pattern changes through the day, giving the facade a dynamic, three-dimensional quality.
Choosing between the two available sizes is one of the most common questions from architects and homeowners specifying this profile. The right choice depends on the scale of your facade, your design intention, and the visual rhythm you want to achieve.
- More boards per m² — finer, more frequent horizontal pattern
- Suits residential projects, extensions, garden rooms
- Works well on smaller facades where a more detailed, refined look is wanted
- Lighter board — easier handling and installation on site
- The most widely specified Lunawood profile in the UK residential market
- Links directly to: triple shadow gap 26x92mm
- Fewer boards per m² — bolder, more pronounced horizontal pattern
- Suits larger facades on commercial buildings, schools, and larger new builds
- Deeper shadow grooves — more dramatic light and shadow effect
- Stronger visual presence — better suited to architect-designed projects
- Increasingly specified on commercial and public building projects in the UK
- Links directly to: triple shadow gap 32x140mm
If you are unsure which size to choose, the 26x92mm is the safe starting point for most UK residential projects — it gives a refined, detailed result that suits the scale of houses, extensions, and garden rooms. Move up to the 32x140mm when the facade area is large enough to carry a bolder pattern — typically when elevations exceed 6–8 metres in width or height, or when the project is commercial or institutional in scale.
Technical Specification
| Specification | 26x92mm | 32x140mm |
|---|---|---|
| Profile | Triple shadow gap — 3 recessed grooves, tongue and groove fixing edge | |
| Species | Lunawood Thermo Pine — Nordic pine (Pinus sylvestris) | |
| Modification process | Thermal modification — heat and steam only, no chemicals | |
| Durability class | Class 2 — BS EN 350 | |
| BRE service life | 30 years — external cladding | |
| Moisture content | Approx 6–8% at point of manufacture | |
| Density | Approx 450 kg/m³ | |
| Colour (unfinished) | Warm honey-brown — weathers to silver-grey | |
| Surface finish | Planed smooth — wire-brushed option available | |
| Certification | PEFC — sustainably sourced Nordic forests | |
| Fire rating (optional) | Euroclass B-s1,d0 — available on request | |
| Installation direction | Horizontal (most common) or vertical | |
| Typical cost per m² | £55–£75 | £65–£85 |
Installation Guide — Key Requirements
Lunawood triple shadow gap in situ — correct batten framework, ventilated cavity, and stainless steel fixings are the three most important installation details for long-term performance.
The Lunawood triple shadow gap installs in the same way as any other horizontal cladding profile — over a ventilated batten framework fixed to the wall substrate. The shadow grooves are self-draining and do not trap water, making this one of the most weather-resistant closed-board profiles available. Here are the critical installation requirements:
Batten framework
Install the boards over vertical counter-battens with horizontal fixing battens attached — creating a clear ventilated cavity of at least 25mm behind the cladding face. This ventilation gap is essential for long-term performance — it allows moisture that gets behind the boards to drain and dry, preventing the build-up that causes premature deterioration on any timber cladding system regardless of species.
Fixings
Always use A4 stainless steel fixings — our PFS C2 stainless steel screws are designed specifically for hardwood and modified timber cladding and are the correct choice for Lunawood triple shadow gap. Standard steel fixings will rust within 3–5 years and create unsightly staining on the cladding face — particularly visible on the pale honey-brown or silver-grey surface of ThermoWood.
Ground clearance
The base of the cladding must be at least 150mm above finished ground level. Ground splash-back is the most common cause of premature deterioration at the base of any cladding system — even ThermoWood will degrade faster if repeatedly wet from below. An open base detail with adequate clearance is one of the most important details to get right at design stage.
End grain sealing
Seal all cut end grain with exterior oil before installation. End grain absorbs moisture significantly faster than face grain — particularly important at the base of each board run and at any horizontal cuts around windows and doors.
Always pre-drill fixing holes when screwing within 50–75mm of the end of any board. ThermoWood pine is more brittle than untreated timber due to the modification process — pre-drilling prevents splitting at board ends, particularly in the 26x92mm size where the board width is narrower.
The Batten Look — Triple Shadow Gap Installed Vertically
The triple shadow gap installed vertically creates a distinctive batten-look effect — the three grooves per board give the impression of narrow vertical battens without the complexity of a true board-on-board system.
One of the less well-known applications of the Lunawood triple shadow gap is vertical installation to create a batten-look effect. When the boards are installed vertically, the three shadow grooves run the full height of the facade, creating a pattern that resembles a narrow vertical batten system without the additional complexity and cost of installing separate cover battens over a flat-board substrate.
This approach is increasingly popular on contemporary UK garden offices, house extensions, and commercial projects where a vertical emphasis is wanted without the higher material cost of a true board-on-board or rainscreen system. The 32x140mm size is generally preferred for vertical installation — the wider board creates a more substantial vertical element and the deeper grooves produce a more convincing batten-look effect than the narrower 26x92mm.
Finishing and Maintenance
Lunawood triple shadow gap weathering naturally — the silver-grey patina develops consistently across the board face and grooves, maintaining the strong shadow line pattern throughout the weathering process.
The Lunawood triple shadow gap requires no preservative treatment in exterior UK applications. You have two main finishing options:
- Leave unfinished — natural weathering to silver-grey. This is the most popular approach and requires no ongoing maintenance beyond periodic cleaning. The honey-brown colour fades and transitions to a consistent silver-grey over 12–24 months depending on exposure. The shadow groove pattern remains clearly visible throughout the weathering process and the silver-grey finish is self-consistent — unlike painted or stained finishes, it does not show UV fading or maintenance lapses.
- Apply a UV-stable exterior oil. This maintains the original honey-brown colour for longer and extends the period before the silver-grey patina develops. Apply within 2–4 weeks of installation before initial weathering begins, and re-apply every 3–5 years on south and west-facing elevations. We stock compatible exterior oils including Koopmans Houtolie and Remmers HK Stain from our woodcare range.
For fire-rated projects where Euroclass B-s1,d0 certification is required, the Lunawood triple shadow gap can be supplied with factory fire retardant treatment through our fire retardant treatment service. For full maintenance guidance see our timber cladding maintenance guide.
The Lunawood triple shadow gap is a ThermoWood cladding profile with three precisely machined recessed grooves across the face of each board. When installed horizontally, the grooves create a strong, repeating horizontal shadow line pattern across the facade. It is produced from thermally modified Nordic pine by Lunawood, with a BRE-accredited 30-year service life. Available in 26x92mm and 32x140mm sizes.
The 26x92mm creates a finer, more frequent horizontal rhythm and suits residential projects, extensions, and garden rooms. The 32x140mm has a wider board and deeper grooves — it creates a bolder, more pronounced pattern suited to larger facades on commercial buildings, schools, and larger new build homes.
Yes — the profile can be installed horizontally or vertically. Vertical installation creates a distinctive batten-look effect with the three grooves running the full height of the facade. The 32x140mm size is generally preferred for vertical installation as the wider board creates a more substantial vertical element.
Lunawood ThermoWood triple shadow gap typically costs £55–£75 per m² for the 26x92mm size and £65–£85 per m² for the 32x140mm size. Add £10–£15 per m² for battens, fixings, and membrane, and £25–£45 per m² for installation labour. Contact Timber Cladding Specialists for a precise quote.
No preservative treatment is required. The boards can be left unfinished to weather naturally to silver-grey, or finished with a UV-stable exterior oil every 3–5 years. Paint or opaque coatings are not normally recommended as they obscure the shadow groove detail that defines the profile.
Lunawood Triple Shadow Gap — Both Sizes In Stock, Nationwide Delivery
We stock Lunawood ThermoWood triple shadow gap in 26x92mm and 32x140mm for immediate delivery across the UK. PEFC certified. Fire rated options available. Send us your dimensions and we will calculate the exact quantity and cost for your project — delivery in 7–14 days.