Facade Cladding
Correct facade cladding protects your building against moisture, wind and fire. Learn about cladding types, air gaps, wind barriers and regulatory requirements.
Common cladding types
| Type | Service life | Fire class | Maintenance |
|---|---|---|---|
| Horizontal timber boards | 20–40 yr | D/E | Paint every 5–10 yr |
| Vertical timber boards | 25–50 yr | D/E | Paint every 8–12 yr |
| Fibre cement | 40–60 yr | A2 | Wash down; minimal painting |
| Brick slip / masonry | 50–80 yr | A1 | Near maintenance-free |
| Steel cassette / trapezoidal | 30–50 yr | A1 | Jet wash; repaint on damage |
| Larch / hardwood | 30–60 yr | D | Oil treatment as needed |
Wall build-up — cross section
From exterior cladding inward to internal lining:
Installation steps
Measure wall areas accurately. Deduct windows, doors and other openings. Add 10–12% for cuts and laps. Plan the starting point — usually a visible corner angle.
Calculate linear metres: Area ÷ visible board width (in metres).
Fix wind barrier membrane (sd-value ≤ 0.2 m) with counter-battens. Overlap at least 150 mm; tape joints.
Screw horizontal battens (36×48 or 48×48 mm) at max 600 mm c/c to create the air gap. Use approved screws — minimum 90 mm into stud.
Fix the first board with a ventilation starter strip. Bottom edge must be at least 250 mm above finished ground level. Check level.
A closing top strip seals the top against eaves or roof edge.
Use stainless or hot-dip galvanised screws/nails. Plain steel or zinc-plated corrodes quickly in coastal climates.
Fix at least 20 mm from board edge. Do not nail into the groove — boards must be free to move.
Corners: use mitre-cut corner trims (80×80 mm) or purpose-made corner boards. Keep maximum 5 mm gap against window reveals.
Seal all gaps with elastic paint-grade mastic — never silicone against timber to be painted.
Exterior timber cladding requires linseed oil primer or paint system. Coat all faces including ends BEFORE fitting — especially soffits!
Aim for 2 primer coats + 2 topcoats. Repeat every 5–10 years depending on exposure.
Local rules and practical requirements
Common mistakes
- ✗Air gap less than 25 mm — causes moisture and rot behind cladding
- ✗Cladding too close to ground (under 250 mm) — moisture wicking and decay
- ✗Untreated end grain — absorbs moisture fastest and rots first
- ✗Wrong screws — black steel corrodes and stains cladding
- ✗No movement joints on long runs (over 6 m without joint) — boards split
- ✗Wind barrier fixed outside the air gap — eliminates ventilation
When to call a professional
- ⚠Cladding on a building more than two storeys — scaffolding, fall protection and fire assessment require a contractor
- ⚠Cladding near a property boundary — fire class assessment and possible building consent required
- ⚠Visible rot or moisture in the existing wall — the damage may extend deeper than the cladding alone
- ⚠Fibre cement and metal cassette systems — these require precise sub-structure design and the correct fixings
- ⚠Listed or heritage buildings — changing material or colour normally requires formal approval
Calculate facade cladding
Use the calculator to estimate linear metres of cladding, wind barrier area and screw quantities.
Open cladding calculator →Frequently asked questions
What air gap is required behind facade cladding?
A minimum 1" (25 mm) ventilated air gap is required behind all cladding types. This allows moisture to escape and prevents rot. SINTEF recommends 1–1.4" (25–35 mm) in coastal climates.
What overlap is correct for horizontal timber cladding?
Standard overlap for horizontal boards is 1.5–2" (40–50 mm). The bottom edge must be at least 10" (250 mm) above finished ground level to prevent moisture wicking.
What fire class does facade cladding need?
Buildings over 2 storeys within 26 ft (8 m) of a boundary typically require at least Class B (European) or equivalent fire-rated cladding. Untreated timber is typically Class D/E — check local building code.
References
- → TRADA — timber cladding specification and durability guidance
- → Equitone / Cembrit — fibre cement cladding technical documentation
- → EN 335 — wood use classes for outdoor cladding (Use Class 3)
- → Local building authority — ventilation gap requirements, fire spread restrictions and wind load calculations for your facade type
Board quantities and fixing counts are indicative. Always follow the cladding manufacturer's own installation guide for your specific product. Last reviewed: May 2026