Shiplap cladding is one of the most popular timber cladding profiles used across the UK, valued for its clean lines, subtle shadow detail, and excellent weather resistance. Whether you’re cladding a garden room, home extension, commercial façade, or interior feature wall, shiplap timber offers a timeless finish that suits both traditional and contemporary designs.
However, to achieve a truly weather-tight, long-lasting result, correct installation is essential. Timber is a natural material that responds to moisture, temperature, and airflow, so understanding how to fix shiplap cladding properly will directly affect its performance, appearance, and lifespan.
In this guide, we explain how to install shiplap cladding step by step, covering preparation, battens, fixings, spacing, finishing, and ongoing care. These best-practice tips are suitable for professionals and confident DIY installers alike.
What Is Shiplap Cladding?
Shiplap cladding is a timber profile where each board is machined with a rebate along both long edges. When installed, the boards overlap slightly, creating a tight joint that helps shed water while forming a smooth, uniform surface.
Unlike tongue and groove, which locks boards together, shiplap relies on overlapping rebates to create weather protection. This makes it particularly effective for exterior cladding, while still offering a neat, refined appearance.
Shiplap cladding can be installed horizontally or vertically and is commonly supplied in durable timber species such as larch, cedar, and Douglas fir.
Why Correct Installation Matters
While shiplap is designed to offer good weather protection, its performance depends heavily on how it is installed. Poor fixing methods, inadequate ventilation, or incorrect spacing can lead to moisture build-up, timber movement, staining, and premature decay.
A properly installed shiplap cladding system will:
- Allow rainwater to drain efficiently
- Enable the timber to expand and contract naturally
- Promote airflow behind the boards
- Protect the structure beneath
- Maintain a clean, consistent finish over time
Taking the time to install shiplap correctly ensures both visual appeal and long-term durability.
Preparing the Timber Before Installation
Before fixing any shiplap boards, preparation is essential.
Store the timber off the ground in a dry, ventilated area, protected from direct rain but not fully sealed in plastic. This prevents moisture build-up and mould.
Allow the boards to acclimatise to site conditions for several days before installation. This helps reduce excessive movement once fixed.
Check the moisture content of the timber where possible. For external cladding, boards should typically be below 16–20% moisture content before fitting.
It’s also good practice to sort boards by width, colour, and grain pattern before installation to achieve a balanced, consistent appearance across the façade.
Installing the Substructure and Membrane
Shiplap cladding must always be installed over a correctly prepared substructure.
Start by fixing a breathable membrane to the external wall. This protects the building from moisture while allowing vapour to escape from inside.
Next, install treated timber battens over the membrane. Battens are usually fixed vertically when shiplap is installed horizontally. Typical batten spacing is 400–600mm centres, depending on board thickness and exposure.
Crucially, leave a ventilated cavity behind the cladding. This airflow gap allows moisture to evaporate and significantly extends the lifespan of the timber.
Ensure battens are level and securely fixed, as they determine the final alignment of the cladding.
Horizontal or Vertical Shiplap Installation
Most shiplap cladding is installed horizontally, which suits the overlapping profile and encourages water runoff. This orientation is ideal for exterior walls and traditional designs.
Vertical shiplap installation offers a more contemporary appearance and can make buildings appear taller. If installing vertically, additional detailing may be required at the base to manage drainage and prevent water tracking behind the boards.
Both orientations work well when installed correctly, so the choice often comes down to aesthetic preference and architectural style.
How to Fix Shiplap Cladding Boards
Begin installing shiplap cladding from the bottom and work upwards.
The first board is critical and must be perfectly level, as it sets the line for the entire installation. Leave adequate clearance from ground level, typically at least 150mm, to prevent splashback and moisture absorption.
Each board should overlap the one below along the rebate, forming a tight but not forced joint. Avoid pushing boards too tightly together, as timber needs room to move.
Fix through the top section of each board, above the rebate. This ensures fixings are concealed by the board above and allows the lower edge to move naturally without splitting.
Always fix into the battens behind, never into the board below.
Choosing the Right Fixings
Fixings play a vital role in the longevity of shiplap cladding.
Stainless steel nails or screws are strongly recommended for external use. They prevent rust staining and offer excellent durability, especially in exposed or coastal locations.
Ring-shank nails are commonly used for cladding due to their strong holding power. Screws may be preferred where future removal or adjustment is anticipated.
Avoid over-driving fixings, as this can restrict natural movement and lead to cracking or distortion over time.
Allowing for Movement and Expansion
Timber expands and contracts with changes in humidity and temperature. Shiplap cladding must be installed with this movement in mind.
Do not force boards tightly together. The overlapping design provides weather protection without needing compression.
At board ends, leave small expansion gaps where appropriate, particularly on longer runs. Butt joints should be staggered rather than aligned vertically to improve strength and visual flow.
These small considerations help prevent warping, splitting, and uneven ageing.
Treating and Finishing Shiplap Cladding
Shiplap cladding can be left untreated to weather naturally, especially when using durable species like larch or cedar. Over time, the timber will develop a silver-grey patina, which many people find desirable.
If you wish to retain the original colour, apply a breathable, UV-resistant oil or stain. This helps protect against sun fading and moisture ingress.
For best results, apply finishes before installation, ensuring all faces and cut ends are coated. This provides more even protection and reduces the risk of moisture penetration.
Any fire-retardant treatments must be applied strictly in line with manufacturer guidance.
Maintenance and Ongoing Care
When installed correctly, shiplap cladding is relatively low maintenance.
Carry out visual inspections once or twice a year, checking fixings, overlaps, and areas exposed to heavy weather.
If the timber has been treated, reapply oils or stains at intervals recommended by the product manufacturer, typically every 1–3 years depending on exposure.
Avoid pressure washing, as this can damage the timber surface and force water into the grain.
Simple care and good airflow will help your shiplap cladding perform well for decades.
Common Installation Mistakes to Avoid
Common issues include installing cladding without a ventilation gap, fixing boards too tightly, or using unsuitable fixings.
Other mistakes include placing cladding too close to ground level, skipping the breathable membrane, or failing to acclimatise the timber before installation.
Avoiding these errors makes a significant difference to both appearance and longevity.
Why Shiplap Cladding Is a Reliable Choice
When installed correctly, shiplap cladding delivers a clean, consistent finish with excellent weather protection. Its subtle shadow lines add depth without overpowering the design, making it suitable for a wide range of projects.
From garden buildings and extensions to commercial developments, shiplap remains a trusted timber profile for good reason.
Get Expert Advice from The Larch Cladding Company
At The Larch Cladding Company, we supply high-quality shiplap cladding in larch, cedar, and Douglas fir, all sourced from responsibly managed forests. We provide expert guidance on profiles, fixing methods, and finishes to help you achieve a professional result.
Contact Us
If you’re planning a shiplap cladding project and would like advice, samples, or a quote, contact our friendly team today. Call 01352 746293 or email info@thelarchcladdingcompany.co.uk to discuss your project with confidence.