25 x 350mm Moisture Resistant MDF Windowboard N&T Primed 3.6m

The 25 × 350 mm Moisture Resistant MDF Windowboard N&T Primed – 3.6 m is a premium internal MDF windowboard designed for very deep window reveals and extra-wide internal window sills. Manufactured from moisture resistant (MR) MDF, it provides excellent dimensional stability and durability in environments exposed to occasional humidity, making it suitable for kitchens, bathrooms and utility rooms.

With an extra-wide 350 mm depth, this primed MDF windowboard is ideal for very deep cavity wall construction, thick masonry and wide reveal applications, offering full coverage over plasterwork, blockwork and window linings. The Nose & Tongue (N&T) profile ensures accurate alignment and secure jointing between boards, delivering a clean, continuous finish across long window openings.

Supplied factory primed, the board reduces on-site preparation and provides an excellent base for a smooth, high-quality painted finish. It is a dependable and cost-effective solution for both new-build and refurbishment interior joinery projects.

Key Features

• Moisture Resistant MR MDF windowboard for internal use

• 350 mm depth – ideal for very deep window reveals and extra-wide sills

• Nose & Tongue (N&T) profile for neat, secure jointing

• 25 mm thickness for strength, rigidity and durability

• 3.6 m length to minimise joints and speed up installation

• Factory primed for quick and easy painting

• Smooth, consistent surface for professional finishes

Typical Applications

• Internal MDF window sills

• Very deep window reveals and extra-wide window openings

• Kitchens, bathrooms and utility rooms

• Residential and commercial interior fit-outs

• New-build and refurbishment projects

Performance & Workability

• Enhanced resistance to moisture compared to standard MDF

• Easy to cut, machine, joint and fix using standard woodworking tools

• Requires only light sanding prior to final paint application

• Intended for internal use only

Technical Specification

• Product Type: MDF Windowboard

• Material: Moisture Resistant MDF

• Profile: Nose & Tongue (N&T)

• Thickness: 25 mm

• Depth: 350 mm

• Length: 3.6 m

• Finish: Primed

• Use Class: Internal

Why Choose a 350 mm MR MDF Windowboard?

The 25 × 350 mm MR MDF Windowboard N&T Primed – 3.6 m is the ideal solution where maximum depth and coverage are required for internal window sills and reveals. Combining moisture resistance, clean jointing and a smooth painted finish, it provides a reliable and economical alternative to solid timber windowboards for modern interior joinery and fit-out applications.