Masterframe Windows

Masterframe Windows is a specialist UK manufacturer of high-quality PVC-U sash windows, with more than 30 years’ experience in the design, development and manufacture of sash windows that combine traditional detailing with modern performance. We only manufacture Sash Windows.

Based in Witham, Essex, Masterframe has built its reputation around one of the most challenging areas of window design: creating authentic-looking sash windows that retain the character and proportions of traditional timber, while delivering the thermal efficiency, security, durability and low maintenance expected from a modern window system.

At the heart of the Masterframe offer are two established sash window ranges: the Bygone Collection and Classic Collection, providing solutions for projects ranging from sensitive period property refurbishment and conservation to new-build developments requiring a traditional aesthetic.

The flagship Bygone Collection comprises Melody, Harmony and Symphony sash windows, with a wide choice of traditional detailing including deep bottom rails, run-through sash horns, slim meeting rails, Georgian bar designs and bespoke colour options. Bygone Symphony can also be specified with FINEO vacuum insulating glazing, achieving a U-value of 1.2 W/m²K while retaining exceptionally slim glazing proportions.

A key feature of Masterframe sash windows is Timberweld® technology. This patented construction method creates authentic timber-style butt joints rather than conventional diagonal PVC-U corner welds. The result closely replicates the appearance of traditional mortise-and-tenon timber construction while creating strong, fully sealed joints suitable for modern PVC-U windows.

Masterframe is the only PVC-U sash window manufacturer licensed to use Timberweld® technology across its Bygone and Classic Collections, helping architects and specifiers achieve the traditional detailing required for heritage-inspired and architecturally sensitive projects without sacrificing modern performance.

Masterframe has continued to develop specialist solutions for challenging replacement projects, including its exclusive London Sash & Frame system. Designed particularly for properties where the original timber window has an arched external frame but a square internal opening, the system enables these distinctive architectural details to be retained while upgrading to a modern, energy-efficient sash window.

With extensive experience in sash window design, manufacturing and technical development, Masterframe works with architects, developers, contractors and specialist installers to provide solutions where appearance, detailing and performance are equally important.