Made for the way you want to live

Each window is built around a precision timber frame, sealed against the British weather and tailored to your home. Choose double or triple glazing, top or side-hung opening, or a fully reversible sash that allows the outside of the glass to be cleaned safely from inside.

Warm, quiet rooms in every season

Triple glazing with U-values down to 0.8 W/m²K

Tested security to Secured by Design standards

Timber from responsibly managed forests

Specifications

The following specifications apply to our traditional double or triple glazed casement windows. Bespoke configurations are available for conservation and listed building projects with specific requirements.

Product guidance – as standard
Frame56 x 90 mm (standard). Manufactured using mortise and tenon joints, glued and mechanically fixed
Sash46 x 68 mm (standard)
Sill projection50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm
Wood moisture content12–19%
Glazing beadsInternally beaded
Product Specification
MaterialEngineered redwood (standard). Engineered hardwood, Accoya, European oak optional
FinishThree-coat spray-applied factory finish using water-based microporous paint/stain
ColourWhite – RAL 9016 (standard). Any RAL from RAL Classic range. Stain from stain range
GlazingDouble glazed, 4/16/4 Low-E (standard). Triple glazing optional
U-value1.2 W/m²K double glazed – 0.8 W/m²K triple glazed
Perimeter spacer barsWhite warm edge perimeter spacer with white warm edge integral spacers (standard). Silver and black optional
Frame profile mouldingOvolo 22 mm, Ovolo 18 mm, Lambs Tongue 22 mm, Lambs Tongue 18 mm
Trickle ventilationThrough sash head trickle ventilator. EA 1700, 4400, 5000 mm²
SecurityCan conform to PAS 24. Secured by Design (SBD) certified
Glazing barsApplied 18 mm and 22 mm glazing bars to external faces of glazed unit
OperationTop hung, side hung, or fully reversible

Authentic Period Detail, Uncompromising Modern Standards

The installation of timber casement windows in a listed building or conservation area demands an exceptional level of precision and period sensitivity. Our traditional double or triple glazed casement windows are manufactured to replicate the exact profiles, mouldings, and glazing bar arrangements of original historic casements – to the point that the replacement is virtually indistinguishable from the original.

We work with architects, conservation officers, and heritage homeowners to ensure every window meets both planning requirements and performance expectations. From the traditional putty glazing and solid ovolo bars to the choice of microporous paint finishes and heritage ironmongery, our timber heritage casement windows are a perfect fit for the most demanding conservation projects.

wooden casement window
casement window frame

Thermal Performance and Acoustic Performance in a Period Frame

Heritage does not mean sacrificing insulation or energy efficiency. Our traditional double or triple glazed casement windows are available with slim double glazing – a 4/6/4 Low-E unit – designed to sit within a traditional putty-glazed profile, delivering measurably improved thermal performance and reduced heat loss compared to original single-glazed casements without altering the window’s visual character.

Acoustic performance is also considered in our design, with the timber frame providing natural sound attenuation and the option for upgraded glazing specifications where noise reduction is a priority. Available in a full range of RAL colours and stain finishes, these windows are an excellent option for homeowners and specifiers seeking the perfect balance of sustainability, durability, and authentic period aesthetics.

Classic Styling with Modern Benefits

Traditional casement windows offer the perfect balance between traditional design and contemporary performance. With authentic detailing and a choice of timber frames, they suit both restoration projects and new developments aiming for a heritage look. Improved glazing options ensure better insulation and acoustic comfort.

triple glazing window

Frequently Asked Questions

Honest answers to the questions homeowners, self-builders and design teams ask most often when choosing a timber casement window.

What our customers say

Quote

Zyle supplied Passive House windows for our new build, and the system met all project expectations. Airtightness and overall performance were delivered as specified, and their technical coordination on site was reliable and detail focused.

Private Owner

Mark Reynolds, Bristol

Quote

Our vacuum glazed sash windows provide an excellent balance between heritage sensitivity and modern performance. The slim glazing preserves the character of the property while significantly improving overall comfort. Installation was precise and professionally managed.

Private owner

Laura Mitchell, Southampton

Quote

The Passive House windows performed exactly as required within our project specification. Installation detailing, sealing, and overall execution were handled correctly, ensuring a high standard of delivery. A technically competent and reliable supplier.

Private Owner

Andrew Collins, Cambridge

Quote

We selected aluminum windows for their contemporary aesthetic and low maintenance. The proportions are well considered, and the finish quality is consistent throughout. Installation was efficient and carried out with strong attention to detail.

Private Owner

Rachel Adams, Reading

Quote

The triple glazed sash windows integrate seamlessly into the existing façade while offering a clear upgrade in comfort. Craftsmanship is evident in both joinery and installation, and the improvement in acoustic insulation is immediately noticeable.

Private Owner

Thomas Green, Nottingham

Quote

The Alu-Clad windows and doors introduced a strong architectural presence while maintaining a refined internal finish. Detailing, material quality, and consistency across the project are of a high standard. The process was structured and dependable from start to finish.

Private Owner

Olivia Bennett, Oxford

Talk to Our Team

Whether you are an architect specifying for a new project, a self-builder planning your custom home, or a developer working to a programme, our team is here to help. Get in touch for technical advice, product information, or to request a quote.

  • 124 City Road
  • London
  • United Kingdom
  • EC1V 2NX

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