W40 Technical Specification

Introduction
A heavy duty framing system introduced in the 1990’s. The windows may be used in all types of building where strong, durable frames, efficient opening casements and robust fittings are required. Projects may be new build or refurbishment where the original fenestration is to be maintained and windows may be manufactured to fit existing apertures. Steel windows are installed using lugs/screws direct to brickwork, concrete and stone or screwed into subframes.

Features include:
W40 is available with multi-point locking, achieving the Secured by Design Standard.  Accommodates glass units to 24 mm.

The W40 range consists of:
Fixed light, top hung, bottom hung, side hung, horizontal and vertical pivots, single and double doors.

Specification
The windows are manufactured generally in compliance with BS 6510.  All frames and ancillary profiles arehot dip galvanizedto EN ISO BS:1461 and available with afactory applied polyester colour coating to EN ISO 13458 BS:6497.

Description
Frames are manufactured from hot rolled mild steel profiles with corner joints mitred, welded and dressed square and flat. Small panes can be formed with tee glazing bars whose ends are tenon-riveted and/or welded to the frame and whose cross joints are interlocked and welded with rigid joints. Composite windows can be assembled by connecting windows horizontally and/or vertically with mullions and/or transoms of hot rolled slim steel profiles, box sections, tubes or box mullions manufactured from sheet steel. Pressed metal cills are available in a choice of profile. All frames and ancillary profiles are hot dip galvanized to BS EN 1461   They can be further finished with a factory applied polyester colour coating to EN ISO 13458 BS:6497.

Glazing
Windows shall be designed for drained and ventilated glazing on site, from inside or outside, of insulating glass units up to 26mm, using factory finished beads and polymer rubber gaskets in accordance with BS 8000-7.

Weatherseals
Ventilators shall be weather sealed with polymer rubber gaskets secured by suitable adhesives.

Dimensions (mm)
Nominal profile width - 40mm
Typical sight lines:

fixed lights perimeter -  <45mm

Hinged or pivoted casements - <70mm

Windows and doors for composite panels are purpose made, generally within the limits shown in the table below; sizes outside these limits may be considered with consultation.

Appearance

W40 is a modern, robust steel window introduced in 1994, ideal for public buildings. Polyester powder coating is available in a range of standard RAL colours.

Performance
Wind resistance, watertightness, air permeabilty
W40 windows have been independently tested to meet the weathertightness – air infiltration, water penetration and wind loading – performance criteria as in BS 6375:1 appropriate to the specified design wind pressure.

BS 6375-1:2009
Air permeability is measured in terms of both area (m³/h/m²) and opening joint length (m³/h/m) against progressively increasing test pressures through 300Pa up to 600Pa for classes 3 and 4. Class 2, or a maximum value at 300Pa of 13m³/h/m, is the UK standard requirement. Watertightness is measured in resistance to leakage at progressively increasing test pressures, 300Pa being considered the most severe UK requirement. The values tabulated in Pascals can also be expressed in classes ranging from 2A (50Pa) through 8A (600Pa) to exceptional resistance up to a maximum of E1050. Wind load resistance entails a deflection test (at 2000Pa for class 5), a repeated pressure test of 50 positive and 50 negative gusts at half the deflection test pressure, and a safety test at 150% of the deflection test pressure (i.e. 3000Pa for class 5). The prefix C means that deflection of the longest frame member was less than 1/300 with less than 1/150 (prefix A) considered adequate in the UK.

Heat

W40 when double glazed with Argon filled low-E warm edge insulating glass units willhave a typical U ‘Value’ of 2.0.

Sound
Average sound reduction index (SRI) of a single glazed unit is approximately 30 dB, but varies with window type and size.