15mm x 120mm x 3900mm Softwood Shiplap Tongue & Groove is an exterior-grade timber cladding profile designed to build durable, weather-resistant outer walls for garden structures and timber-framed outbuildings.

Primary Uses & Key Features

• Garden Outbuildings & Sheds: Commonly used to construct, repair, or re-clad garden sheds, summerhouses, workshops, home offices, and playhouses.

• Garages & Carports: Provides a clean, protective external timber skin for timber-framed garages, carports, and outdoor storage bays.

• Integrated Water Shedding: Combines the interlocking fit of a tongue-and-groove joint with the scalloped rebate of a shiplap profile. This creates a flat surface that channels rainwater down and away from the building, keeping interior spaces dry.

• Structural Wall Strength: The interlocking tongue-and-groove design binds adjacent boards together, distributing wind load and adding structural rigidity to the wall frame.

• Versatile Finishing Base: Machined from kiln-dried softwood that easily accepts exterior wood stains, paints, oils, or clear preservatives to match surrounding garden aesthetics.

Available for collection from our Rugby branch or local delivery using our own fleet.

Delivery is kerbside and the final offloading position is always subject to safe access and the driver’s discretion.

Please tell us before delivery about:

• Narrow roads or restricted entrances
• Parked vehicles or limited turning space
• Overhead cables, trees or other obstructions
• Soft, sloping or unsuitable ground
• Any other access concerns

Enter your postcode on the product page to check your delivery area. We’ll confirm the delivery date after your order is placed.

What is the difference between standard shiplap and shiplap tongue-and-groove?

Standard shiplap relies purely on overlapping rebates to shed water. Shiplap tongue-and-groove features a physical tongue that inserts into an internal groove along with the outer scalloped rebate, providing superior draughtproofing, structural rigidity, and wind-driven rain resistance.

Should an air gap be left behind the cladding during installation?

Yes. Always nail vertical timber battens to the wall frame first and fix the cladding onto the battens. This creates a 25mm ventilated cavity behind the boards, allowing moisture to evaporate and preventing damp from transferring into the building framework.

Can 15x120mm shiplap T&G be installed vertically?

While designed primarily for horizontal placement to shed water naturally, it can be installed vertically if a double-batten system is used behind it. However, the top and bottom board ends must be cut at an angle or protected by trim to prevent water soaking into the end grain.

What size gap should be left between board joints?

When slotting the tongue into the groove during installation, leave a 1mm to 2mm expansion gap inside the joint. Softwood cladding absorbs moisture from atmospheric humidity and will expand across its width; leaving room prevents the boards from cupping or pushing off the wall.