SMW+ Range

Suitable for heritage windows

The SMW+ range of windows uses steel window sections from the SMW (Standard Metal Window) "F" series, the original domestic steel window manufactured since the 1920s and installed into thousands of properties throughout the world. Although the SMW range is still used today for conservation projects, it is only available single glazed. The SMW+ range addresses this by way of using specialist reduced-height warm edge technology sealed unit spacer bars, and a dual-seal glazing method - ensuring the longevity of the sealed unit whilst maintaining SMW aesthetics.


Due to the small window sections, only 10 mm - 12 mm sealed units can be fitted and therefore the range will not meet the criteria of the Building Regulations (Document L - Conservation of Fuel and Power). However, by using special sealed units, centre-pane glass U values (Ug) of 1.9 W/m2K or 2.1 W/m2K can be used which are significantly more energy-efficient than single glass panes, which have a relative centre pane U value of 5.7 W/m2K.

Through its small and profiled sightlines, the SMW+ window has unrivalled elegance, which coupled with enhanced thermal insulation makes it an ideal window for replacing existing SMW windows, especially those installed prior to 1948 when the rust-proofing galvanised coating was first introduced.

SMW+ windows are the natural replica replacement product for SMW windows in recognised historic or aesthetically sensitive buildings or areas as they offer an exact sightline match for the existing and may, therefore, be exempt from Building Regulations Document L (Conservation of Fuel and Power). If you require fully compliant double glazed domestic replacement steel windows, please refer to our W10 and W30 ranges. Exemptions are likely (subject to gaining the necessary permissions from the relevant governing authority) to include buildings that are:

- Listed
- In a designated conservation area
- A scheduled ancient monument
- In a designated building of architectural or historic interest
- In a national park or area of outstanding natural beauty
- Buildings of traditional construction with permeable fabric that
both absorbs and readily allows the evaporation of moisture.

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.

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.


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