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Our Heritage Timber Casement Windows are designed to replicate the traditional appearance of period casements while delivering modern performance. Each window achieves whole unit U-values between 1.6 and 1.7 W/m²K, with laboratory-tested acoustic ratings of up to 31 dB. Weather resistance is equally robust, with Class 7A water tightness and Class 4C wind resistance.
Manufactured from engineered timber such as redwood, hardwood, Accoya or oak, every frame is factory finished with a three-coat microporous paint or stain for long-lasting durability. Slimlight glazing units between 12–16mm maintain the authentic appearance of single glazing, while offering the insulation benefits of a sealed unit.
With options for traditional glazing bars, varied cill projections, ironmongery finishes and trickle ventilation, these casement windows can be specified to suit a wide range of heritage or conservation projects.
Product Guidance
| Frame | 55 x 105 mm - Standard. 55 x 86 Optional. Manufactured using mortise and tenon joints, glued and mechanically fixed. |
| Sash | 42 x 45 mm - Standard. |
| Mullion/transom | 12-19%. |
| Sill projection | 35 mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm. |
| Wood moisture content | 12% +/- 2% on delivery. |
| Glazing beads | External Traditional putty glazed. |
| Air Permeability | 600 Pa (Class 4) EN 12207: 2017 |
| Water Tightness | 300 Pa (Class 7A) EN 12208:2002 |
| Wind Resistance | 1600 Pa (Class 4C) EN 12210:2016 |
| Whole Window U-Value | Thermal performance is calculated by the standards of EN ISO 10077-1:2006 and achieves a U-value of 1.6 -1.7 W/m²K depending on the type of timber, unit thickness and type of cavity gas used. |
| Whole Window Acoustic rating Rw, dB | Acoustic rating is Laboratory tested to BS EN ISO 10140-2: 2010 (Airborne Sound Insulation). Window Acoustic ratings Rw 28-31dB. |
| Anticipated Life Expectancy | 60 years with the regular maintenance |
Product Specifications
| Material | Frame and sash in engineered redwood, bottom cill in solid hardwood (standard), engineered hardwood, Accoya, or European oak. |
| Finish | Three coat spray applied factory finish using water based micro-porous paint/ stain. |
| Colour | White - RAL 9016 - Standard. Any RAL - from RAL classic range. Stain - from TRC stain range. |
| Glazing | Double slimlight glazed, 4/6/4 Low-E top sash – 4 toughened/6/4 toughened bottom sash – Standard. Single Glazing of 4 mm or 6mm thick toughened - optional. |
| Perimeter spacing bars | White perimeter spacer - Standard. Black spacer optional. |
| Solid Bar | Ovolo 24 x 45mm. |
| Trickle ventilation | Through sash trickle ventilator. EA 1700, 4400, 5000 mm². |
| Child restrictor | Child safety catch type restrictor - standard. |
| Operation | Sashes are hung and operated on the butt hinges and locked by espagnolette locking mechanism, using lockable fastener and casement stay. |
| Timber Species | Manufactured in selected engineered laminated pine, hardwood or Accoya, sourced from sustainable and managed forestry (FSC or PFEC certified). |
| Moisture Content | 12% +/- 2% on delivery. |
| Glass | The windows to be factory fitted with 12, 14 or 16mm thick sealed double “slimlight” glazing unit Tested to BS EN1279 Parts 2 & 3. Composition of glass units is to be (from outside): 4mm float – 6mm argon, krypton or Xenon filled cavity /4mm float glass with Low-E coating. Other glazing combinations are available on request. The height of the sidelight of the DGU is not less than 8.5mm. Perimeter spacer in white or black. |
| Glazing Bars | Solid traditional framed glazing bars with individual glass units. |
| Ironmongery | Espagnolette mechanism with lockable casement fastener and casement stay with options in colour and finish. |
| Cill | 35 mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm. |
| Ventilation | A controllable EA 2000, 4400mm² trickle ventilator can be fitted to the window dependant on width of frame. |
| Finish as Delivered | Window supplied factory finished, externally and internally with Teknos Water-based micro porous opaque to specified RAL colour, or stained finish. Aqua prime 1410, Aqua mid-2901, Aqua top 2600. |
| Restrictors | Optional restrictors allow the opening of the sash to be restricted to 100mm. |
| Fixing | Installation to be carried out using best building practices and in conjunction with recommendations of TRC windows. |
| Warranty | Manufacturing and Material Defects: 10-year guarantee. Finishes: The standard three-coat opaque finished joinery guaranteed for 10 years. The stain finishes guaranteed against blistering or flaking for six years. Seals: The seals on double-glazed units are guaranteed for 10 years (from the date of delivery). Ironmongery: Functional failure is guaranteed on ironmongery for two years. |
Technical Drawings
U-values as low as 1.6W/m²K.
Manufactured in redwood, hardwood, Accoya, or European oak.
Child safety catch restrictors supplied as standard.
10-year guarantees on finishes, glazing seals, and defects.
Hardwood cills available in sizes from 35–110 mm.
Colour options include any RAL shade or TRC stains.
Browse completed installations showcasing TRC’s craftsmanship across a range of properties.
Our heritage timber casement windows are designed with the fine proportions and detailing needed for period projects. Frames and sashes are built using mortise and tenon joints for strength, while feature options such as solid glazing bars and traditional ironmongery finishes ensure an authentic appearance.
Each window is manufactured from sustainably sourced redwood, oak, hardwood or Accoya, then factory finished with a three-coat microporous paint or stain. Cill projections from 35mm to 110mm are available, along with trickle ventilation and optional restrictors for added safety.
From bespoke glazing layouts to a full palette of RAL colours, every element can be specified to meet the requirements of your property. Installed with care by TRC’s specialist team, these casement windows deliver the detail and longevity expected in heritage settings.
Heritage casement windows are a traditional style of window that can add character and charm to any property. These outward-opening windows are hinged at the side or top, allowing for flexible ventilation and clear views. They have been a common feature of British architecture for centuries and are often found in historic buildings and period homes.
Here at TRC Windows, we are passionate about preserving the heritage and character of these windows while also improving their performance and energy efficiency. Our expert craftsmen use traditional methods and materials to create bespoke casement windows that are tailored to your individual needs and preferences.
Our windows are made from high-quality, sustainably sourced timber, and are designed to blend seamlessly with the original architecture of your home. We offer a range of glazing options, including slimline double glazing, to improve energy efficiency and reduce noise pollution.
We also provide a choice of additional features, such as draught-proofing, trickle ventilation and secure locking systems, to ensure that your heritage casement windows are not only authentic in appearance but also functional and secure. Our team of experienced TRC fitters will install your new windows with care and precision, ensuring a perfect fit and a durable finish.
Whether you are looking to restore your period home or add traditional detail to a modern property, TRC Windows has the expertise and experience to create the perfect heritage casement windows for you. Contact us today using the form below to discuss your requirements and arrange a consultation with one of our friendly team members.
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