W40 Windows

Suitable for commercial windows

An evolutionary development from W20, W40 offers continuity of style with the same casement sightlines as W20, but the 40mm wide profiles permit the use of double or triple glazing up to 26.8mm thick. The insulating glass units are drained and ventilated in accordance with modern best practice and gasket glazed to ensure consistent neatness and reliability of the seal. In addition to improved thermal performance, weather-tightness is significantly enhanced and has a less obtrusive fitting with variable geometry hinges, friction pivots and multi-point locking cremone bolts concealed within the profiles. W40 achieves the Secured by Design standard (please see W40-SBD product).


W40 range is available in a plain galvanised finish in addition to an extensive range of RAL colour polyester powder coat finishes

The W40 range of profiles is the most heavy-duty of the available mild steel window ranges and thus offers the client the best choice of opening window and doors types and the widest range of permitted sizes. Sightlines, being that of the W20 range, are not compromised by the increased strength and this allows the architect complete design flexibility whilst maintaining the slim elegant aesthetic, which is synonymous with mild steel windows.

A large range of quality modern or traditional face-mounted ironmongery can be fitted, in addition to restrictors, background trickle ventilators and security locks. All available with a range of attractive finishes in addition to standard finishes of satin chrome plate or RTD RotoTone Dark bronze lacquer. Main ironmongery, comprising handles and stays, are generally solid brass. W40 range is also unique in that it also permits the use of variable geometry concealed hinges and multi-point locking systems.

A key part of BS 6510, adhered to by Steel Window Services, is positive protection from rust. Frames of hot-rolled solid steel are hot-dip galvanized after fabrication to BS EN ISO 1461. During this process, the windows are thoroughly cleaned and then dipped in a bath of molten zinc. The zinc reacts with the iron in the steel to form alloy layers, which are then covered with pure zinc as the window is withdrawn. This combination of soft zinc over hard alloy layers produces a highly durable protective coating that will not flake or peel. In the event of accidental damage, the galvanized coating will corrode in preference to the steel which prevents rusting.

Galvanized steel windows do not require painting for protection but their appearance is enhanced by the addition of a factory-applied polyester colour coating. Polyester coatings have a life expectancy of at least 15 years and a comprehensive range of colours is readily available, with the matt finish proving most popular because of its surface enhancing properties.

A small selection of the extensive RAL colour choices for powder coating new steel windows.

The durability and high performance of steel windows can be enhanced even further if good maintenance practices are observed.

Frames should be cleaned at regular intervals using a mild, non-alkaline detergent in warm water, applied with a soft cloth or sponge.

Glazing and perimeter sealants should be inspected on an annual basis and appropriate maintenance action should be taken.

Galvanized steel windows, which are not factory finished with a polyester colour coating, are manufactured with clearances to allow for up to three or four coats of paint on the meeting surfaces. When the repainting programmed has exceeded this, the paint should be stripped off all meeting surfaces prior to repainting.

All hinges, pivots, handles, stays and other mechanical parts should be checked for operation, kept free of excessive paint build-up and lightly lubricated.

Full O & M Manuals (Operation and Maintenance Manuals) are supplied by Steel Window Services upon request on any new window project.

Steel is the first choice for keeping intruders out. Our trade association, the Steel Window Association is an accredited group organisation of Secured by Design, the official UK Police initiative focussing on the design and security of new and refurbished homes, which promotes products such as steel windows that have passed its security tests.

Following successful tests for enhanced security to BS 7950, W40 products, open both inward and outward, fitted with concealed multi-point locking bolts and friction stay hinges or brass butt hinges, satisfy the Secured by Design standard.

The concealed multi-point locking system handle can be locked in a slightly open position to give background trickle ventilation.

Face-mounted key lockable bolts are available in extra-long lengths for high reach applications.

The W40-SBD range is the Enhanced Security version of our successful W40 commercial grade hot rolled mild steel range.

A range of approved modifications have been made to the W40 range to enable it to comply with the Secured by Design standard and these are summarised below:


a) "Magnum" Variable Geometry friction hinges with either "Dog Bolts" on the hinge side or proprietary hinge protector fittings (all concealed when the window is in the closed position), or
b) Type 1260 traditional brass face-fix butt hinges with security pin (may be required for larger windows or for conservation reasons).

Glazing Beads



Opening Window Types

An extensive range of opening windows is available in the W40-SBD range, but types are limited to those listed in BS7950. This permits the use of hinged and fixed windows, but not folding double casements or pivoting windows. Please refer to the "Key facts and features" to below for full details of permitted types.


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