1. How do steel-framed windows compare with other materials for strength, security and maintenance?
Steel is inherently the strongest frame material for windows and doors. It is three times stronger than aluminium, for example. But this strength is combined with elegance. The profile (sightline) of a steel window is much less than that of its aluminium or uPVC counterparts. Frame-for-frame, the slender appearance allows for a greater surface area for the glazing, and, indeed, larger expanses of glass can be achieved while retaining an aesthetic appearance. The steel frames are almost virtually maintenance-free. They are hot-dip galvanised and finished with a factory-applied Duralife polyester powder coating in accordance with BS EN 13438. Thus, protected products have a life expectancy in excess of 60 years. The strength of the material and multi-point locking also greatly enhance the security of the buildings in which they are installed.
2. What about thermal performance? Isn’t steel cold?
Window frames made from traditional rolled steel are energy-efficient – incorporating high-performance weather seals, insulating double or triple glazing and narrow sightlines that enhance U-values and reduce energy consumption.
A T60 thermally-broken window features an advanced high-density polyurethane isolator as a thermal barrier. This, together with housing high-performance double- or triple-glazing up to 45mm wide, ensures the system surpasses the requirements of current regulations, offering overall U-values as low as 0.8W/m²/K. Market-leading weathertightness performance has been tested to European and ASTM standards.
Alternatively, ultra-insulating glass units use suspended film technology in a double-glazed unit to convert it to provide triple-glazed performance. Ultra IG’s innovative design results in a thinner and lighter construction compared to traditional triple glazing and superior performance, offering U-values as low as 0.4W/m²/K in a double glass unit, without increasing glazing thickness or weight.
3. What about noise reduction?
Measures taken to improve thermal performance also effectively insulate against noise. And where steel-framed glazed screens and doors are specified for building interiors, sound attenuation, rather than weathertightness, is key. According to the usage – in a home, an office or a school – appropriate sound reduction is achieved by acoustic glazing that leaves the width of the slim steel frames unaltered so that they can admit the maximum amount of daylight throughout the building.
4. Protection against fire for internal glass screens?
The Innervision FR steel-framed system is compliant with BS 476 Part 22, providing 30 minutes (FD30) integrity fire resistance whilst preserving its unique slender steel profile – which sets it apart from other bulkier fire-rated systems.
5. How do steel’s environmental credentials match up?
Increasingly, this is becoming a vital issue for buyers. They want to be sure that the product purchased is produced from sustainable materials and uses eco-friendly, energy-efficient processes – also that the end product is energy efficient with exceptional life expectancy.
Put simply; steel is one of the most recyclable materials on the planet. It can be recycled and reused continuously.
Means of manufacture and standard business practices are also designed to reduce energy consumption. For example, Crittall has fitted solar panels to the factory roof, installed energy-efficient LED lighting that reduces energy consumption by 50% while simultaneously improving light levels, and introduced electric hybrid vehicles to the company fleet.
The firm operates an ISO 14001-accredited Environmental Management System, which involves setting targets for reducing energy consumption, eliminating waste and recycling materials with the ultimate objective of creating a closed-loop manufacturing process. The company’s products are also made from 100% recycled steel.
6. Are steel windows suited to new build or refurbishment?
They are equally suited to both. Crittall’s business spans three centuries, from the middle of the 1800s. There are many heritage buildings that were built with original Crittall windows. When refurbishment work is undertaken, local planners demand a like-for-like replacement for historical and aesthetic reasons. This can be achieved while installing windows that now meet modern thermal and acoustic requirements while remaining faithful to the original appearance.
Architects designing modern buildings also value the clean lines and simple elegance of steel windows that – with large expanses of glazing – augment elevations, whether on commercial, business, educational or residential premises. Steel frames can also be supplied in the full range of BS and RAL colours.
7. What does steel offer the homeowner, especially in the post-COVID world of work?
The pandemic has caused many working professionals to reassess whether they need to continue to travel into urban centres or whether they should work from home and adjust their living space accordingly. The use of internal glazed screens, as detailed above, can help provide a suitable workspace in the house, with maximum daylight but minimal noise disturbance. Crittall has established an online community where customers can exchange these and other ideas and solutions to improve their homes and businesses using its products.
8. In a sentence, why choose steel?
An initial higher investment in steel-framed windows and doors will be offset by its longevity and reduced maintenance, leading to lower, long-term costs compared with other materials, and steel is beautiful.