Intermediate

Wood cladding facade: boards, battens and breather membrane

20/04/2026 14 min read

Once the house is weathertight and the windows are in, it’s time to dress the facade. Wood cladding is the go-to solution for contemporary or timber frame houses: ventilated insulation, warm aesthetics, low maintenance and a lifespan of 40 to 60 years when correctly installed. But a cladding system lives or dies in the details — forget the air gap, pick the wrong breather membrane, use steel nails instead of stainless, and the facade blackens, warps and rots within five years. This guide covers the full method to French DTU 41.2 standard: species choice, profiles, battens, breather membrane, ventilation, critical details and cost per m².

Anatomy of a ventilated wood cladding

Wood cladding is never fixed directly to the wall — that’s the golden rule. You must use a ventilated multi-layer system that separates each function:

Load-bearing wall (blockwork, concrete, timber frame): structure and bracing
Insulation (internal or external depending on the system)
Bracing panel or rigid sheathing board (OSB, wood fibre)
HPV breather membrane (Highly Vapour-Permeable)
Vertical battens (primary fix) fixed through the membrane to the studs: they create the ventilated cavity
Horizontal counter-battens (for vertical cladding) or direct fix to battens (for horizontal cladding)
Wood cladding boards fixed to the battens

The air cavity between breather membrane and cladding is the heart of the system. It:

Drains away moisture the wood absorbs through capillary action (driving rain)
Allows the wood to dry after every shower
Creates a convection effect that limits summer overheating
Prevents standing water against the breather membrane

Warning — Fixing cladding directly to a breather membrane or to a wall without battens is a classic self-build mistake. Without a ventilated air cavity, the wood stays permanently damp, sapwood blackens within two years, and the cladding rots in five. The minimum cavity depth is 22 mm (recommended: 27 to 40 mm).

Choosing your timber species

Not all species are equal for facade use. The criteria are: use class 3b minimum (timber exposed to water, above ground), dimensional stability, natural durability and appearance as it weathers.

Species	Natural use class	Lifespan	Indicative price	Recommended use
Douglas fir (sapwood-free)	Class 3 natural	40-50 years	£30-45/m²	French standard choice, excellent value
Larch	Class 3-4 natural	50-60 years	£40-65/m²	Mountain regions, harsh climates, noble look
Western Red Cedar	Class 2 natural	40-50 years	£75-110/m²	Premium, outstanding dimensional stability
Sweet chestnut	Class 3 natural	40-60 years	£45-75/m²	Regional, rustic appearance
Scots pine pressure-treated	Class 3 treated	20-30 years	£18-30/m²	Budget option, green tint
Thermo-treated spruce	Class 3 thermally modified	25-35 years	£35-55/m²	Modified wood, stable amber colour
Composite WPC	Not applicable	25-30 years	£55-90/m²	Zero maintenance, variable look

Tip — For a self-build project, French Douglas fir, sapwood-free is the best all-round choice. Widely available, naturally durable, affordable, and locally sourced — it grows in the Massif Central, Burgundy and the Morvan. Always specify “sapwood-free” on your order: the sapwood (the pale outer ring) lacks the durability of the heartwood (the red core) and rots in five years. See our full guide on timber species and use classes.

Minimum clearance from ground level

Under the French DTU 41.2 standard, the first board must sit at least 200 mm above finished floor level (20 cm) to avoid capillary moisture rise and water splash. On exposed sites or sloped ground, increase this to 300 mm.

Available board profiles

The profile determines the aesthetics, the installation method and the weather resistance under driving rain. Six profiles dominate the market.

The 6 common profiles

Question

Lap siding (weatherboard) — Horizontal fixing, each board overlaps the one below by 20-25 mm. Excellent water drainage, traditional look. The most forgiving profile for installation errors.
Tongue and groove (T&G) — Interlocking boards with hidden fixings through the tongue. Clean, modern, perfectly aligned appearance. More expensive, more technical.
Open-joint (rainscreen) — Boards spaced 5-20 mm apart, UV-resistant black membrane (EPDM or bituminous) mandatory behind. Strongly contemporary look, ideal for design timber frame houses.
V-groove — Deep groove simulating open-joint, but boards are butted tight. Design aesthetic without the black membrane requirement.
Channel groove (canal-U) — Contemporary profile with a deep groove, wide boards (140-180 mm). Architectural impact.
Shiplap (rebate) — Half-lap rebate on each edge, boards flush with a flat finish. Anglo-Saxon inspiration, fast to install.

Best practice — For a first self-build, go for lap siding (weatherboard). It’s the most forgiving profile: if a board is 2 mm out of line, the overlap compensates and water still drains. With tongue and groove, a single twisted board creates a chain of defects that runs all the way up the wall.

The breather membrane: role and choice

The breather membrane is a flexible sheet fixed to the rigid sheathing (OSB, fibreboard panel) or directly to external wall insulation (EWI). Its role:

Block water that penetrates behind the boards (driving rain, wind-blown snow)
Allow water vapour to pass through from inside (perspiration)
Protect the insulation from wind (windbreak effect)

Technical specifications

Criterion	Target value	Notes
Vapour permeance (Sd)	< 0.2 m (HPV)	Lower = more breathable wall
Water resistance (hydrostatic head)	> 1,500 mm	Standard for driving rain
UV resistance	3-4 months exposed	Time before cladding is fixed
Weight	110-220 g/m²	Heavier = more robust

Common brands in France: Delta-Vent, Siga Majvest, Pro Clima Solitex, Isover Vario Xtrasafe.

Warning — Never confuse breather membrane and vapour control layer (VCL). The VCL (warm side, inside) blocks vapour. The breather membrane (cold side, outside) blocks water but allows vapour through. Swapping the two creates condensation inside the insulation, destroying the wall buildup within a single winter. See the vapour control layer article to understand wall physics.

Installing the breather membrane

Horizontal overlap: 100 mm minimum between two runs, upper run laps over the lower (following water flow).
Vertical overlap: 100 mm, sealed with breather membrane tape at joints.
Stapling to rigid sheathing or studs, on the exterior side (hidden behind battens).
Critical details (window reveals, external corners): bond with MS polymer adhesive or purpose-designed tape.
Vermin mesh at the bottom of the cladding to stop mice and insects colonising the air cavity.

Battens and ventilated cavity

Batten size and species

Standard section: 22 × 40 mm to 27 × 50 mm (rectangular, fitted on the narrow face against the wall).
Species: spruce/fir use class 2 if concealed, Douglas fir or larch use class 3 recommended for durability matching the cladding.
Spacing: 600 mm centres for standard horizontal cladding in 21-27 mm boards; reduce to 400-500 mm for thin boards or highly exposed sites.

Installation

Vertical battens for horizontal cladding (most common case).
Horizontal battens then vertical battens (double battening) for vertical cladding: the counter-batten maintains ventilation.
Fixing: stainless steel A2 screws (normal zone) or A4 (coastal) into structural studs or hammer fixings into masonry.
Minimum clearance from ground: leave 30-50 mm between the bottom of the battens and ground level to allow air entry.

Ventilation: airflow in and out

The air cavity must be continuous from bottom to top of the wall. It needs:

An air inlet at the bottom (ventilated vermin mesh, 5 mm maximum mesh size)
An air outlet at the top (under the roof overhang / eaves, via a grille or purpose-designed profile)

Without this upward airflow, the cavity becomes a damp, stagnant chamber and the whole system loses its point.

Installation steps, in order

Tip

Step 1 — Prepare the substrate

OSB panel or fibreboard sheathing nailed to the frame, panel joints centred on a stud. Clean, dry, flat surface (tolerance: 10 mm over a 2 m straight edge).

Step 2 — Fix the breather membrane

Roll out horizontally from bottom to top, 100 mm overlap downwards (following water flow), staple to the outside face, seal all joints with HPV adhesive tape.

Step 3 — Fix the battens

Snap chalk lines for vertical centres at 600 mm. Fix battens with stainless screws through the breather membrane (the perforations seal around the screw shaft — no leak path). Check plumb with a laser level.

Step 4 — Fit the vermin mesh

Staple a perforated PVC or aluminium strip (5 mm maximum mesh) along the full width at the base of the battens, lapping over the breather membrane.

Step 5 — First board (starter board)

The lowest board must be perfectly level — check with a laser or chalk line. It sits at a minimum of 200 mm above finished floor level. Any error here multiplies across all 30 boards above.

Step 6 — Build up the cladding

Fix board by board using overlap (lap siding) or interlock (tongue and groove). Fix with annular-ring nails or stainless screws, 2 fixings per batten, heads flush (never countersunk into the wood).

Step 7 — Critical details

Corners, window reveals, arrises: use purpose-made profiles, corner trims or return boards. See the section below.

Step 8 — Top finish

Fascia board or capping board at the top of the cladding, to shed water and close the ventilated cavity outlet neatly.

Warning — Fixings must be exclusively stainless steel A2 (normal zone) or A4 (coastal / pool areas). Galvanised steel screws or nails rust within 2-3 years on contact with the tannins in timber (oak, chestnut, Douglas fir) and cause permanent vertical black staining. The stainless steel premium is around £25 per 100 m² of cladding — trivial compared to the visual damage of a stained facade.

Critical details

The details are what separates cladding that lasts 40 years from cladding that rots at the corners in five.

External corners

Three solutions:

Corner cover strip (added timber profile) — easy, covers cut ends
Metal angle trim (powder-coated aluminium, zinc) — slim, modern finish
Mitre joint (45° cuts) — cleanest result but technical, for experienced builders

Internal corners

A corner batten where the boards from each face butt up, or an internal corner trim. The goal: leave a 3-5 mm gap for thermal movement.

Window reveals

Return board or aluminium stop profile at the back of the reveal, against the window frame.
Window sill flashing (aluminium or zinc) with a drip edge and upstand under the breather membrane.
Sealant with MS polymer between window frame and return board — never between cladding and window frame (the timber must be free to move).

Horizontal junctions (floor break)

Z-flashing or double batten with the ventilated gap maintained. Ventilation must continue across this junction.

Maintenance and weathering

Natural weathering

With no treatment at all, wood cladding gradually turns silver-grey through UV exposure. This is not a sign of decay — the timber remains mechanically sound as long as it dries properly. Complete greying takes 1 to 3 years depending on exposure.

You have three choices:

Choice	Result	Maintenance
Nothing — let it grey	Patinated look, silver-grey on south face, dark grey on north	None
Wood oil saturator (pigmented mineral oil)	Preserves original tone, warm matte finish	Apply every 3-5 years
Microporous wood stain	Thin tinted film, stabilised colour	Apply every 5-7 years, strip if peeling

Avoid film-forming paint

A thick paint (acrylic, alkyd) creates an impermeable film that stops the wood breathing. When moisture migrates from inside out, it stays trapped under the film → blistering, peeling, mould. Film-forming paint and exterior wood cladding do not mix.

North-facing walls: watch for moss

North-facing or shaded facades develop moss and lichen. Treat every 2-3 years with a mild acidic anti-moss product (diluted oxalic acid, or a commercial cleaner), light brushing, then let the rain rinse it.

Cost of installed wood cladding

2026 price ranges (labour included)

Species / profile	Installed cost per m²
Treated Scots pine, lap siding	£50-75
Douglas fir sapwood-free, lap siding	£75-110
Douglas fir or larch, tongue and groove	£90-130
Douglas fir or larch, open-joint	£100-150
Western Red Cedar, lap or T&G	£140-200
Thermo-treated wood, contemporary profile	£120-165
Composite WPC	£110-165

For a house with 140 m² of facade

Douglas fir lap siding, contractor-installed: £10,000 to £16,000
Douglas fir lap siding, self-build (materials only + fixings + battens + membrane): £4,500 to £7,000
Self-build saving: £4,000 to £8,000 depending on choices and site complexity

Tip — Wood cladding is one of the most cost-effective tasks to do yourself in a self-build. The technique is accessible, the tools are basic (circular saw, drill/driver, level, chalk line), and the flat surface of a wall is forgiving for beginners. Start with a gable end in horizontal lap siding (most forgiving) before tackling large main facades or tongue-and-groove profiles.

Decision tree: which cladding to choose?

flowchart TD A{House style?} -->|Traditional / rustic| B{Budget per m2?} A -->|Contemporary / design| C{Look you want?} A -->|Timber frame RE2020| D{Exposure?} B -->|Tight 20-40 eur| E[TREATED PINE
horizontal lap siding] B -->|Standard 40-70 eur| F[DOUGLAS FIR
lap or shiplap] B -->|Comfortable 70+ eur| G[LARCH
lap or tongue and groove] C -->|Clean lines| H[TONGUE AND GROOVE
Douglas fir or larch] C -->|Vertical rhythm| I[OPEN-JOINT
black EPDM membrane] C -->|Strong contrast| J[CHANNEL GROOVE
wide boards] D -->|Coastal| K[LARCH + A4 fixings
or Western Red Cedar] D -->|Mountain| L[LARCH or
thermo-treated wood] D -->|Inland standard| M[DOUGLAS FIR
lap or tongue and groove] style A fill:#0F4C81,stroke:#0F4C81,color:#fff style B fill:#0F4C81,stroke:#0F4C81,color:#fff style C fill:#0F4C81,stroke:#0F4C81,color:#fff style D fill:#0F4C81,stroke:#0F4C81,color:#fff style E fill:#FDB813,stroke:#FDB813,color:#fff style F fill:#56C6A9,stroke:#56C6A9,color:#fff style G fill:#56C6A9,stroke:#56C6A9,color:#fff style H fill:#56C6A9,stroke:#56C6A9,color:#fff style I fill:#F58220,stroke:#F58220,color:#fff style J fill:#F58220,stroke:#F58220,color:#fff style K fill:#6B5876,stroke:#6B5876,color:#fff style L fill:#6B5876,stroke:#6B5876,color:#fff style M fill:#56C6A9,stroke:#56C6A9,color:#fff

Common mistakes to avoid

Forgetting the ventilated air cavity — timber stays wet, rots in 5 years
Using galvanised steel fixings → permanent vertical black staining
Confusing breather membrane and vapour control layer → condensation in insulation
First board too close to the ground (<200 mm) → capillary moisture rise
Leaving sapwood on Douglas fir boards → rotten patches within 3 years
Applying a film-forming paint (alkyd, thick acrylic) → blistering and peeling
Forgetting the vermin mesh → mice nesting, wood-boring insects
Butting boards too tight without expansion gap → boards cup or split
Fixing to a damp wall (concrete or blockwork less than 4 weeks old) → mould behind cladding
Neglecting critical details (corners, reveals) → water ingress, delamination

Standards and references

DTU 41.2 (French standard) — External timber cladding: the reference standard, defines installation rules, admissible use classes, batten sections, fixings and ventilation
NF EN 350 — Natural durability of wood (defines use classes)
NF EN 335 — Use classes according to moisture exposure
FCBA — French timber technology institute, technical datasheets and training
Codifab — French timber and furniture industry body, free technical resources

Checklist before you start

Useful links

Before cladding, check the condition of your roof structure and underlay — the cladding’s top ventilation outlet connects to the eaves overhang
Wood cladding is the natural solution for timber frame houses — fixed directly to studs without masonry
Masonry alternative: monocouche render for a mineral finish or traditional lime render for heritage buildings
For opening details, see the article on window sills and external thresholds
Deepen your timber knowledge with our guide on species, use classes and treatments