The EcoTherm SL casement door is designed around practicality and durability, using highest quality materials throughout. Its versatile design suits a broad range of projects – from modern homes to period properties – with easy operation, clean lines, and a timeless appearance that remains as relevant in twenty years as it does today. A perfect choice for homeowners and specifiers who demand both functionality and precision.
Full technical specifications for the EcoTherm SL casement door range – refer to the table below for standard product data.
| Product guidance – as standard | |
| Type | Entrance Door, single/double; Terrace Door, single/double; Paneled Door single/double. |
| Configuration | Inward-opening / Outward-opening |
| Frame | 56 x 102mm - for Double Glazed Scandi and 56 x 112 for Triple Glazed Scandi Plus doors. Manufactured using mortise and tenon joints, glued and mechanically fixed. |
| Product specification | |
| Material | Engineered redwood – Standard. Engineered hardwood, European oak. |
| Glazing | 28mm Double glazed unit of 4/20/4 Low-E – as standard for Scandi. 48mm Triple glazed, 4/18/4/18/4 Low-E – as standard for Scandi Plus. |
| Perimeter spacer bars | White warm edge perimeter spacer- as standard. Silver and black spacer optional. |
| External finish | Polyester powder coating. |
| Internal finish | Three coat spray applied factory finish using water-based Teknos micro-porous paint/stain. |
| Energy characteristics | Single Door U-value of 1.36 W/m²K using double-glazed units of 28 mm with a center U-value maximum of 1.1 W/m²K. Single Door U-value of 0.91 W/m²K using triple -glazed units of 48 mm with a center U-value maximum of 0.53 W/m²K. |
Download technical datasheets, performance data, and BIM files for specification and design use.
The EcoTherm SL casement door is a popular choice across a wide range of residential and commercial projects in the UK, valued for its ease of operation, clean lines, and adaptable specification options. Available in both inward and outward-opening configurations, it brings practicality and natural light together in a single, well-resolved product.
The versatile design means the EcoTherm SL casement works equally well in contemporary homes and more traditional settings. Whether specified at width for a generous, light-filled opening or in a narrower configuration for a more considered entrance, the door accommodates a broad range of architectural briefs without compromise.
For homeowners and specifiers seeking a low-maintenance casement door, our aluminium cladding option provides a practical and long-lasting solution. The Aluclad system protects the engineered timber core against harsh UK weather conditions, retaining its finish and colour for years without the need for repainting or retreatment.
The exterior cladding is available in a wide selection of colour options – applied as a durable polyester powder coat – while the interior retains the warmth of natural timber with a three-coat factory-applied Teknos finish. The result is a casement door that stands the test of time in both performance and appearance, representing a high security, high-quality choice for any project.
Here are answers to some of the most common questions about our EcoTherm SL casement doors – from glazing options to finishes and performance data.
Contact UsThe Scandi double-glazed casement door achieves a U-value of 1.36 W/m²K, while the Scandi Plus triple-glazed version achieves 0.91 W/m²K – making it a strong choice for energy-conscious projects across the UK.
Yes. All EcoTherm SL casement doors are available in a wide range of colours. The external aluminium cladding is powder coated, and the internal timber finish is factory-applied using Teknos micro-porous paint or stain.
The Scandi uses a 28mm double-glazed unit, while the Scandi Plus uses a 48mm triple-glazed unit – delivering a significantly lower U-value of 0.91 W/m²K for projects requiring higher thermal performance.
The Scandi Plus triple-glazed casement door, with a U-value of 0.91 W/m²K and centre pane U-value of 0.53 W/m²K, is well suited to low-energy and Passivhaus-standard projects across the UK.
EcoTherm SL casement doors are manufactured using engineered redwood as standard, with engineered hardwood and European oak available. All frames use mortise and tenon joints, glued and mechanically fixed for precision and durability.
Whether incorporated into a modern contemporary new build or unlocking a period property, our curtain wall can reinvigorate a property by letting the natural daylight come flooding in.
Find out more about Dollar, ScotlandA complete service
from design to installation.
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
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
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
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
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
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
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.
Please complete the form below to access this download.
