Traditional Box Sash Windows

These timber sash windows embrace the all style and function of traditional box sash windows, yet are enhanced with modern construction and materials. Smooth-running and robust, they feature a classic weight-and-pulley mechanism.

Suitable for non-listed buildings and contemporary developments, our sash windows come in a selection of hardwood and softwood frame finishes, plus RAL colours, to provide freedom of design.

With the option of safety glass, obscured glass, acoustic glass or solar control glass, our wooden double-glazed sash windows can be tailored for every situation.

These box sash windows offer impressive technical performance too, demonstrated by wind load testing, water permeability and air tightness test results.

For heritage sash windows for historic and listed buildings, please browse our heritage windows and doors section.

Traditional Box Sash windows Zyle Fenster
100 x 160 mm (lining width x frame depth), manufactured using mortise andtenon joints, glued and mechanically fixed.
39 x 55 mm top rail and stiles, 90 x 55 mm bottom rail, 45 x 55 mm meeting rail.

Mullion / Transom

200 mm wide (130 mm for triple sash with fixed outer
Sill Projection
35 mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm
Staff / parting beads
Wood moisture content
Glazing beads
Internaly beaded.
Frame+Sashes Engineered redwood, Bottom Cill in Solid Hardwood – Standard. Engineered hardwood, Accoya, European oak.
Three coat spray applied factory finish using water based micro-porous paint/ stain.


White – RAL 9016 – Standard. Any RAL – from RAL classic range. Stain – from TRC stain range.
Double glazed, 4/16/4 Low-E top sash – 4toughened/16/4 toughened bottom sash – Standard, Ug-value: 1.1 W/m²K; g-value: 0.52;
1.5 W/m²K – double glazed.
Perimeter spacer bars
White warm edge perimeter spacer with white warm edge integral spacers – Standard. Silver and Black spacer optional.
Frame profile moulding
Ovolo 1, Ovolo 2, Lambs Tongue.
Trickle ventilation
Concealed through frame head trickle ventilator. EA 1700, 4400, 5000 mm²
Child Restrictor
Angel lock standard. Traditional Sash Stop optional.

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