Aluminium Windows

Technical Specifications

DTW specifies aluminium window systems from Smart Systems and Cortizo — two of the UK's most rigorously tested manufacturers — selected on a project-by-project basis to deliver optimal thermal performance, security compliance, and aesthetic precision across all window types.

System Performance Overview

• Thermal Performance: U-values from 1.0 W/m²K (triple glazed, high-performance units); standard double glazed from 1.4–1.6 W/m²K depending on system
• Security: All systems PAS 24:2022 certified; Secured by Design available across the range
• Weather Performance: Air permeability Class 4; watertightness Class 5A–9A; wind resistance tested to Class AE 2400 or above (BS 6375-1:2009)
• Frame Depths: 47–77mm depending on system; polyamide thermal break technology throughout
• Glazing: Double or triple glazed units; 24–54mm unit thickness depending on system and specification
• Document L Compliance: All systems Building Regulations compliant for new build and major refurbishment
• Finishes: Full RAL powder coat palette; anodised options; dual-colour inside/outside available

System Selection

• Steel Look / Heritage: Smart Systems Alitherm Heritage — 47mm frame, 59mm sightlines, conservation-area approved
• Slimline Casement / Tilt & Turn: Smart Systems Alitherm 400 — optimised for contemporary new-build and refurbishment
• High-Thermal / Triple Glazed: Cortizo COR 70 — U-values to 0.83 W/m²K, glazing up to 54mm

Each project receives a system recommendation based on planning requirements, thermal targets, structural constraints, and design intent. DTW's manufacturer-agnostic approach means the right system is specified every time, not the most commercially convenient one — a distinction that matters to architects, developers, and homeowners who require performance evidence for planning submissions, SAP calculations, and building control sign-off.

Glass Options

All our aluminium windows are available with a choice of high-performance glazing to suit your project requirements:

• Double-glazed sealed units — standard specification for thermal efficiency
• Triple-glazed units — enhanced thermal and acoustic performance
• Acoustic laminated glass — for noise reduction in urban and roadside locations
• Solar control glass — reduces heat gain and glare while maintaining natural light

We specify the optimal glass configuration for each project based on thermal performance, acoustic requirements and Building Regulations compliance.