Built around a timber frame and operated on traditional cords, weights and pulleys, our traditional sash window is internally beaded for security and finished with slim glazing bars. The result is an authentic sash you can live with: warmer, quieter and safer than the original.
The following specifications apply to our traditional sash windows . Bespoke configurations are available to suit your project requirements.
| Product guidance – as standard | |
| Frame | 100 x 140 mm (lining width x frame depth). Mortise and tenon joints, glued and mechanically fixed |
| Sash | 39 x 45 mm top rail and stiles, 90 x 55 mm bottom rail, 45 x 55 mm meeting rail |
| Mullion / transom | 39 x 45 mm top rail and stiles, 90 x 55 mm bottom rail, 45 x 55 mm meeting rail |
| Sill projection | 35 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm |
| Staff / parting beads | Timber |
| Wood moisture content | 12–19% |
| Glazing beads | Internally glazed with timber beads |
| Air permeability | 450 Pa (Class 3) – EN 12207:2017 |
| Water tightness | 200 Pa (Class 5A) – EN 12208:2002 |
| Wind resistance | 1600 Pa (Class 4C) – EN 12210:2016 |
| Whole window U-value | 1.5–1.4 W/m²K to EN ISO 10077-1:2006 |
| Whole window acoustic rating | Rw 29–38 dB tested to BS EN ISO 10140-2:2010 |
| Anticipated life expectancy | 60 years with regular maintenance |
| Product Specification | |
| Material | Frame and sashes engineered redwood, bottom cill in solid hardwood (standard). Engineered hardwood, Accoya, European oak optional |
| Finish | Three-coat spray-applied factory finish using water-based microporous paint/stain (Teknos Aqua prime 1410, Aqua mid 5200, Aqua top 2600) |
| Colour | White – RAL 9016 (standard). Any RAL from RAL Classic range. Stain from Zyle Fenster stain range |
| Glazing | Double glazed, 4/16/4 Low-E top sash – 4 toughened/16/4 toughened bottom sash (standard). Ug-value 1.1 W/m²K; g-value 0.52 |
| Glass standard | Factory-fitted 24–44 mm sealed double-glazing units tested to BS EN 1279, argon filled |
| Perimeter spacer bars | White warm edge perimeter spacer with white warm edge integral spacers (standard). Silver and black optional |
| Solid bar | Ovolo 1, Ovolo 2, Lambs Tongue |
| Glazing bars | Applied bars to both faces of sealed unit, fixed with double-sided glazing tape and capped with clear silicone |
| Trickle ventilation | Concealed through frame head trickle ventilator. EA 1700, 4400, 5000 mm² |
| Child restrictor | Angel lock (standard). Traditional Sash Stop optional |
| Operation | Cord, weight and pulley system concealed within the frame |
| Timber species | Engineered laminated pine, hardwood or Accoya. FSC or PEFC certified |
| Moisture content | 12% +/- 2% on delivery |
| Ironmongery | Lockable Fitch fastener and two finger pulls to bottom sash. Options in antique brass, polished chrome, satin nickel, polished brass, matt bronze, polished nickel |
| Cill | Hardwood. Projections 35–110 mm |
| Horns | Solid feature horns to top sashes included as standard |
| Restrictors | Optional restrictors limiting opening to 100 mm |
| Fixing | Installation per Zyle Fenster recommendations and best building practice |
| Warranty | 10-year manufacturing and material defects; 10-year opaque finishes; 6-year stain finishes; 10-year sealed unit seals; 2-year ironmongery |
Download the Traditional Sash Window brochure, datasheets and CAD details for your project.
The traditional sash window has been a defining feature of British domestic architecture for centuries. Our handcrafted versions preserve that classic design – complete with traditional timber horns, authentic mouldings, and counterbalance cord and pulley systems – while meeting the expectations of today’s living space requirements.
For period homes, conservation areas, and listed buildings, the box sash window remains the popular choice. It offers unique character that modern alternatives simply cannot replicate, making it an excellent choice for property owners seeking to preserve the authentic look of their building without sacrificing energy efficiency or comfort.
Every timber frame is manufactured using mortise and tenon joints, glued and mechanically fixed for structural integrity and long-term durability. Frames and sashes are produced from engineered redwood as standard, with options including Accoya, engineered hardwood, and European oak for projects with more specific requirements or environmental priorities.
Finished with a three-coat micro-porous factory spray in a wide range of colours – including any RAL classic shade or a choice of stain – our traditional sash windows are as considered in their appearance as they are in their construction. The result is a more comfortable living environment and complete peace of mind for clients and specifiers alike.
Our traditional sash windows retain the elegance of classic timber designs while benefiting from modern materials and construction methods. Smooth operation and durable finishes make them a dependable choice for both period-style homes and newer properties seeking a timeless appearance.
Honest answers to the questions homeowners and self-builders ask when restoring a period home or specifying traditional timber sash windows for a new build.
Yes. Sash horns, glazing bar profiles and meeting rail proportions are all made to suit Georgian, Victorian or Edwardian properties, with applied bars in Ovolo or Lambs Tongue profiles.
They will. Whole window U-values of 1.4 W/m²K and acoustic performance up to 38 dB make a significant difference compared with original single-glazed sashes, especially in town and city locations.
Internal beading, multi-point locking and security-rated glazing allow the window to meet PAS 24:2016, the same standard used to certify modern Secured by Design windows.
With routine maintenance and recoating, traditional sash windows have an anticipated service life of around 60 years, supported by a 10-year manufacturing warranty.
Yes. Any colour from the RAL Classic range or a wood stain from our range can be hand-applied at the factory, so the windows arrive on site fully finished.
A complete service
from design to installation.
We purchased a combination of Alu-Clad windows, Lift & Slide doors and entrance glazing from Zyle Fenster for our family home.
Every member of the team was knowledgeable, approachable and highly professional. Manufacturing quality is outstanding and the installation was carried out with real attention to detail. Even after completion, they followed up to ensure everything was perfect.
It’s rare to find a company that delivers exactly what they promise. We would happily recommend Zyle Fenster to anyone building or renovating a home.
Seán & Emma R. – County Meath
Our architect specified Reynaers aluminium systems and recommended Zyle Fenster for the supply and installation.
The large glazing panels have completely changed the feel of the house while maintaining excellent thermal comfort throughout the winter. The installers were meticulous and every junction was finished beautifully.
It’s refreshing to work with a company that genuinely cares about delivering a quality result.
Niamh F. – County Clare
We chose Schüco aluminium windows and doors through Zyle Fenster for our contemporary home.
Everything about the experience was professional. From technical advice through to installation, the team demonstrated real expertise. The slim profiles look fantastic and the quality of the finish is exactly what we hoped for.
A premium product installed by a premium company.
David L. – County Waterford
Our conservation project required slim glazing without compromising performance, and Zyle Fenster recommended their vacuum glazed timber sash windows.
The result is outstanding. The traditional appearance has been preserved while the improvement in warmth and noise reduction is remarkable. You simply wouldn’t know they contain such advanced technology.
Excellent communication, excellent installation and an exceptional product.
Michael & Sarah K. – County Kilkenny
Finding authentic timber sash windows that also met modern energy standards wasn’t easy until we found Zyle Fenster.
The finished windows perfectly suit our Victorian home while dramatically improving comfort. They operate beautifully and the attention to detail is outstanding.
The installation team treated our home with great respect and left everything spotless each evening. We have received countless compliments from neighbours.
Margaret C. – Dublin
We wanted a large glazed feature overlooking the garden while still achieving excellent thermal performance. The timber curtain wall supplied by Zyle Fenster exceeded every expectation.
The craftsmanship is remarkable and the amount of natural light it brings into the house is incredible. Our architect was particularly impressed with the technical knowledge and attention to detail shown throughout the design process.
Professional, reliable and extremely high-quality workmanship.
Patrick D. – County Wicklow
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.
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