EXTENDING THE SERVICE LIFE OF STEEL WINDOWS
Certain attributes of steel window frames – such as strength, security and the slenderness of section sightlines – are accepted by virtually everyone concerned with the construction industry, yet many specifiers and building owners do not understand the extent to which the performance and longevity of even early models can be stretched by specialists in steel window refurbishment and repair.
As well as the installation of new, high performance W20 and W40 frames, complete with IG units able to meet the requirements of Part L to the Building Regulations, members of the Steel Window Association offer a comprehensive remedial service that encompasses many levels of intervention, from adjustment and aesthetic repair, through to full overhaul back in the factory.
What approach is taken will vary according to factors such as the building’s level of exposure, whether it is listed and the overall cost compared to outright replacement. In respect of the latter course of action, the SWA – in common with conservation groups and local councils – would normally recommend a like-for-like approach in order to preserve the property’s architectural integrity.
The likelihood is that the windows can be restored to their original pristine condition and improved upon in terms of future weather resistance, energy performance and resistance to forced entry.
SWA members have the experience and the resources to address different problems with steel and the earliest wrought iron frames, whilst respecting the surrounding building fabric and all the legislative requirements, including health & safety.
Pre-war steel windows did not benefit from the protection of factory applied hot dip galvanising, and have, unless meticulously maintained, suffered from varying degrees of corrosion. In turn, the expansive nature of iron oxide can crack the glass, or even cause spalling of the window reveal.
Dealing with the problem in-situ, the contractor will normally employ a variety of hand and power tools to remove all visible signs of rusting, getting back to clean metal before applying one of the specialist coatings now available to prevent future corrosion.
It may be the case that the work reveals some frame areas, where water has collected, have been almost completely ‘eaten away’ and more radical treatment is required. A skilled operative will be able to cut out the affected section with a disc-cutter or hacksaw and weld in a matching section of metalwork, before completing its concealment. It may also be necessary to straighten out twists that have occurred due to structural or thermal movement. Misalignment between coupled, multi-light windows can be similarly rectified.
Redecorating the repaired window can be achieved using either brush applied or sprayed paint systems, including suitable primers and undercoats, with proven products on the market now being able to achieve greatly extended maintenance cycles.
As well as the steel frames themselves, the window’s ‘ironmongery’ is almost certain to require some attention. This could include easing, adjusting and lubricating or replacing the hinges. Likewise the window stays and handles can be cleaned up, repaired, adjusted and redecorated. Then depending on the location of a building or window, and therefore its perceived vulnerability to burglary, the client may wish to have improved or additional locks fitted. Again in heritage situations, SWA members have access to ranges of replica handles and other furniture.
It may be deemed necessary or desirable to replace or add new weather-seals where the opening lights close against the main frame. The contractor can also reseal the perimeter of the window where it is built into the brick, stone or other material of the reveal.
The glazing obviously has a huge effect on the energy performance of any fenestration system and SWA members can undertake a host of improvements.
Depending on the age and type of the frame, the glass or glazing unit might be retained by lead cames, putty, sealants or some sort of bead; all of which may be removed and replaced. Where heritage demands it contractors can source new sections of so called crown glass with its characteristic distortions. Alternatively, later windows can have single glazing replaced with some of the slimmer double glazed units – incorporating low-E glass and gas filling – to drastically cut the centre pane U-value.