Your windows, given a new lease of life

This service is especially useful for steel windows (sometimes referred to as "Crittall Windows") in buildings which are listed or are of special interest, where a sympathetic refurbishment of the existing frames would always give a better end result than attempting a sometimes inappropriate replica replacement. The budget may also be a contributing factor as despite however inclusive a specification of refurbishment is, the cost will nearly always be less than replacement in steel.

Refurbishment, as opposed to replacement, also has substantially less environmental impact, especially if the windows are upgraded in terms of airtightness and thermal insulation during the works. If it is decided to refurbish, the following main points should be addressed.


The most common complaint made of old steel windows is the operation of the opening windows and the force that is required to close them. This also, in turn, leads to the ironmongery (mainly handles and hinges) being damaged by the force they are under.

This problem can be relatively easily rectified by a skilled refurbishment by Steel Window Services. The problem exists because, before the modern-day method of factory polyester powder coating steel windows was introduced, all steel windows were painted on site. Subsequent redecorations usually then consisted of a light rub down followed by additional coats of paint. The build-up of paint around the hinge and pivot areas would then lead to distortion of the frames where the opening windows have been forced closed.

The opening sashes should be serviced, eased and adjusted - an operation which comprises a very skilled method of easing, adjusting and lubricating the hinges and pivots/ironmongery and easing the frame members back to square.

Only very distorted frame members will require the frames to be de-glazed prior to and re-glazed (with new glass) after the straightening works.

The window frames will require redecoration after these works are completed due to unavoidable damage that will be caused to localised paint areas.

Should any externally exposed surfaces be taken back to bare steel during this operation, the affected areas should be coated with a rust-inhibiting primer paint (non-galvanised surfaces) / specialist primer (galvanised surfaces). This will temporarily protect the surface from corrosion before decorators are employed to redecorate.

Due to the problems with opening windows as described previously, and through general wear and tear - ironmongery gets broken or goes missing throughout the life span of a steel window. This also includes the hinges and pivots.

A complete range of ironmongery, hinges and pivots are available to replace existing missing or defective items. This range includes new modern designs to suit the taste of the individual should all ironmongery be required to be changed for aesthetic reasons, and also includes a range of period and original ironmongery where part replacement is required. Ironmongery to match as closely, if not exactly to the original design is available to ensure continuity with existing ironmongery that is present and correct. Brass replica-replacement ironmongery can also be cast to match the existing.

If the problem is with worn pins, rests or brackets that support ironmongery - these can be individually replaced. All replacement parts are generally drilled and tapped into the steel window sections to ensure a good fastening.

It should be noted that if the reason for the ironmongery being missing or defective is that the windows are needed to be forced to operate, the windows must be serviced, eased and adjusted prior to ironmongery works being carried out.

Should replacement hinges or pivots be required - this usually involves a requirement for external access to the windows concerned. Therefore, the cost is usually prohibitive for the sake of the occasional hinge and the window should then be sealed shut until external redecoration is carried out.

Inappropriate ironmongery replacement should be rectified by either moving ironmongery to make matching sets throughout the building, by replica replacement from stocks, or by casting new matching brass pieces if quantities make economical.

If broken or cracked glazing exists, panes can be replaced by using the below methods:

Putty glazed panes
• Rake off old glazing putties
• Remove broken pane
• Clean out all mastics from the glazing rebates
• Treat any signs of rust within the glazing rebates and coat affected areas if necessary with a rust-inhibiting primer paint (non-galvanised surfaces) / specialist primer (galvanised surfaces)
• Supply new pane of glass to match original (if still available, or nearest type if not)
• Re-putty glaze with new glazing sprigs (where required) and non-setting metal casement putty. New glazing putties will require redecoration. An allowance of at least 1-2 weeks (less if a rapid set putty is used) after glass installation should be made to allow the new putties to "skin" over before decorating to ensure the surface of the putty is not "scored" by the action of the paintbrush bristles if it is not set sufficiently.

Glazing safety note
Due to current health and safety regulations, insurance limitations and the general safety of public and property, there are certain restrictions governing the replacement of glass. Definite exclusions would include removing the glass from a window that was over a public area that could not be cordoned off sufficiently around the working base plus an area around the perimeter equal to the distance that a piece of glass could "sail" out once airborne. The actual pane to be replaced must also not be above first floor level from a secure platform suitable for mounting of a ladder base if there is no access to the outside of the broken pane via a directly adjoining opening window.

Pressed galvanised steel channel beads
Clip overglazing studs using corner clips. Usually 8mm, 9.5mm or 13mm front to back and usually either 9.5mm or 13mm high.

Extruded aluminium sloping profile channel beads
Clip overglazing studs using no corner clips.

Metal or Hardwood beaded glazed panes
Secured by visible screws on tops of beads.
• Remove and dispose of any old glazing beads, corner clips, glazing studs, springs or screws.
• Remove broken pane
• Clean out all mastics from the glazing rebates
• Treat any signs of rust within the glazing rebates and coat affected areas if necessary with a rust-inhibiting primer paint (non-galvanised surfaces) / specialist primer (galvanised surfaces)
• Re-drill and tap steel glazing rebates
• Supply and fix new glazing studs or screws
• Supply new pane of glass to match original (if still available or nearest type if not)
• Re-glaze pane using Butyl non-setting metal casement glazing compound with a colour sympathetic to frame colour. Alternatively - glaze pane using setting and spacer blocks and apply a silicone cap back and front, or solid bed depending on frame system, to provide a longer life seal
• Supply new metal beads to match existing
• Supply and fix corner clips to bead intersections
• Decorate new metal beads

If glazing beads, corner clips and studs or screws can be removed and reused without damaging them, then this method will be used in lieu of the above due to cost and time savings in addition to guaranteeing a matched final product.

Leaded light panes
It is possible to replace individual broken panes of leadlight, whether diamond or rectangular, without the need to replace the whole leadlight or remove it from the window.

Individual panes of leaded and coloured/stained glass windows can be replaced without replacing the whole leaded light or removing the window.

It is often found in commercial buildings, where there are many floors involving larger than average opening windows such as the modular window designed buildings of the 1950s and '60s, that the window fixings and intermediate window coupling fixings have loosened off or sheared off. This is especially evident in the higher floors where windows have been more open to the weather and therefore the wind loadings applied to the face of the windows are much greater.

The SWS refurbishment of the existing steel windows at the BBC West One Project in London W1 was an integral part of this major redevelopment

These fixings can be tightened or replaced, as necessary, relatively easily. The only problem that may occur is when the fixing end is concealed under the glass edge (which is common on steel windows). This is only applicable to fixed light panes and not opening lights where the fixing screws are visible when the window is open. In this case - the fixed lights panes must be hacked out and re-glazed as described in the last section.

Many windows for about the last 30 years have had as an option, a weatherstrip applied to opening windows, which is concealed when the window is shut. This was, and still is, fixed to enhance the weathering capabilities of the windows and to stop draughts, water and noise penetration. This usually takes the form of (W20) a black neoprene rubber "fin" that is glued into a preformed groove in the inner moving frame section or (SMW) a black neoprene double-bladed rubber gasket that is factory pre-fitted into an aluminium housing strip that is fixed to the moving frame. The only other factory weatherstrip that was fitted was a large black neoprene gasket "fin" strip that occurs on SMW reversible horizontal pivot casements (mainly on blocks of flats). This last type is easily identified in that it is the only type that was fitted by clamping it between two separate steel frame members during construction. More recently, manufacturers tend to use one of the new technology highly adhesive surface mounted EPDM or similar compressible rectangular tapes.

If any of the above types of weatherstrips have been painted over on-site, it is likely that they have broken down due to a chemical reaction between the paint and the weatherstripping. This results in the seal prematurely hardening, cracking and falling off. In this case, there is no option, but to replace them. This is possible with SMW and W20 windows, and any system using the surface mounted seals, but not SMW Reversibles.

The gaskets in W20 windows can be cut out and replaced with matching gaskets, which are glued with a suitable adhesive to the original groove.

The gaskets and housing aluminium strip can be replaced to SMW windows. Note: this type of weatherstrip can only be replaced on existing SMW windows which presently have it fitted. Existing SMW windows without weatherstrips fitted cannot be fitted with it as special holes for the fixings have to be punched into the sections in the factory. Existing SMW windows presently not fitted with weatherstrips can be silicone draught proofed as described in the Upgrading section.

The gaskets in SMW reversibles cannot be replaced as they are secured to the frames by two separate steel window sections which are clamped together. Should weatherstripping need to be reintroduced to this type of window, the silicone draught-proofing system as described in the Upgrading section should be used.

Any defective surface mounted seals can, at the end of their lifespan, generally be replaced relatively easily with a matching seal.

During the long life of a steel window, the sealants used in sealing windows to their structural openings and the seals between window frame elements will eventually break down.

It is vital that mastic seals are re-applied to open joints such as these

Sealant technology in the 1930s was not as good as it is today and with modern chemicals - the sealants used today have a much longer life. Therefore, the seals may have to be re-made to existing windows.

The method of carrying out these works is to firstly remove and rake back all old sealants during servicing and overhaul works. Once the window frames have been redecorated - the seals can be re-introduced. This should be done after a sufficient amount of time has elapsed for the paint to dry.

The external perimeters can be silicone sealed with a triangular fillet of (dependent on structure and paint surface) low modulus gun-grade silicone sealant.

Intermediate couplings which project from the outside of the window face can also be sealed in the same way.

If the building is an active building site, it is often prudent to wait until all demolition works are completed as dust will adhere straight to silicone and it cannot be removed after. Under no circumstances should the silicone be painted after application as this will break the silicone seal down.

As opposed to re-glazing an entire pane (see "Broken or cracked glazing") - there may be a requirement to just replace individual glazing beads. This may be because of abuse, or because of (in the case of hardwood) - natural deterioration.

Although it is possible to replace individual beads because glazing rebates usually need to be re-drilled and tapped for either glazing bead studs or bead screws, this work may result in accidental breakage of the glass pane.

Therefore it is sometimes (especially if more than one bead per pane requires replacement) more economical to evaluate a job cost accounting for the entire pane to be replaced, including its four beads.

Special profiled hardwood beads can be designed to match existing where part replacement is required. Metal clip on beads are still available.

Refer to "Broken or cracked glazing" section for details of bead replacement methods which are the same as if you were replacing a pane.

Putty glazed panes
Putty glazed panes in steel windows must be monitored closely to ensure that the putty has not broken down as this is the largest contributing factor to the rusting of un-galvanised (pre-1948) windows, and will undoubtedly result in the eventual, and sometimes costly, replacement of the windows. This is even more important when decorations have not been carried out periodically.

Externally puttied panes, or internally puttied panes in bathrooms/kitchens (where there is a high level of humidity in the room causing condensation on the glass), are especially at risk. The visible signs of deterioration of glazing putties are cracks in the surface of the putty or a distinct gap between the putty and the glass. This problem should be rectified as soon as possible as these cracks will let water into the glazing system where it remains trapped. The only path for it then to follow is into the steel. In the case of un-galvanised steel windows, the steel is very susceptible to corrosion through water penetration into the glazing system. This is evident by rusting of bottom members or horizontal glazing bars. If the problem has not been caught in time and the steel members are badly corroded - the window will usually require replacement. However, if the steel is able to be refurbished, then the below methods will be used to repair small areas of putty.

• Rake off old glazing putties
• Clean out all old mastics from the glazing rebate,
• Treat any signs of rust within the glazing rebate and coat affected areas if necessary with a rust-inhibiting primer paint (non-galvanised surfaces) / specialist primer (galvanised surfaces)
• Re-putty glaze with new glazing sprigs (where required) and non-setting metal casement putty. New glazing putties will require redecoration by others after re-glazing is carried out. Please allow at least 1-2 weeks (less if rapid set putty used) after glass installation to allow the new putties to "skin" over before decorating. This will ensure the surface of the putty is not "scored" by the action of the paintbrush bristles if it is not set sufficiently.

Bead glazed panes
Bead glazed panes give a longer life to the steel window than putty glazed panes as above. Generally, bead glazed (either steel clip-on, solid steel or hardwood) panes were glazed using either a Butyl type non-setting metal glazing compound in a solid bed, using setting/spacer blocks and capped back and front, or solid bed with a silicone sealant. The latter gives a longer life.

The only point that should be checked is the condition of the glazing mastic seal between the bead edge and the glass face. In the case of butyl glazing compounds, due to the life span being less than silicone, the compound may have hardened and cracked. This can be easily rectified by scraping out the old mastics and replacing with new. The same method can be applied to silicone capped panes although this is a longer process.

Silicone should never be painted over and if windows are site painted - decorators may have painted the silicone which would lead to the premature breakdown of silicone seals.

All old metal glazing beads and corners such as these can be easily sourced from stock and replaced

Steel windows before 1948 were not galvanised, although for a few years before this time - an initial coating of red lead paint was applied to deter rusting of the members. Rust is not generally associated with Steel windows after 1948 but whilst the galvanising technique was going through improvements in the first few years the coating was not as advanced as it is now and therefore not fully effective.

Therefore, windows from the early 1950s should not be showing signs of corrosion except for:
• Localised areas where the galvanised coating was not applied correctly at manufacture
• Windows have been physically damaged, penetrating the protective zinc coating
• Windows were not galvanised as they were manufactured by a company that stayed with the Red Oxide method of rustproofing.

Most rust is completely treatable.

Windows prior to this period are very susceptible to corrosion if site decoration is not kept up every seven or so years. This decoration should also include (if applicable) the replacement of glazing putties to stop water ingress to un-reachable areas under glass. Signs that this has not been carried out correctly are usually evident in rusting of the bottom sections and horizontal glazing bars. 99 % of commercial standard Universal Section steel profile bars used up to about 1965 are no longer available and because the front-to-back dimensions are different from the ones used today in the equivalent W20 section, individual corroded bars cannot generally be cut out and new re-welded back in to replace them although solutions can often be found using alternative section profiles.

The SMW "F" series of steel domestic and light commercial sections is the same now as it was before, more or less, and therefore theoretically, it is possible to cut out defective corroded bars and replace them with new bars.

In the case of surface rust, which is not seated into the steel sections, this can usually be rectified by a competent decorator in the preparation of frames by rubbing down, treating affected area with a rust neutralising solution and then priming with a rust-inhibiting primer paint (non-galvanised surfaces) / specialist primer (galvanised surfaces) prior to normal redecorations.

If there are local deep-set corroded areas, these can be raked out to the best steel possible before treating affected area with a rust neutralising solution, priming with a rust-inhibiting primer paint (non-galvanised surfaces) / specialist primer (galvanised surfaces), over-filling (for later rubbing down, feathering and preparation by the decorator) the repair with either a bulk metal filler or chemical metal prior to normal redecorations.

If the rust is extensive, and cannot be dealt with locally as there are simply too many repairs to carry out, or there is a high chance that the rust is too far advanced and will come back through the newly decorated surfaces - then either the replacement of the frames will be required or a more extensive refurbishment is required. The following section covering the "condition of painted surfaces" outlines Steel Window Services additional full strip renovations, which would deal with most windows with mass corrosion.

Existing steel windows will be one of two painted finishes (if not left in a plain galvanised finish). The first will be site painted and the second; a factory applied polyester powder coating.

The latter finish is a very durable finish and should give no problems for a minimum of 15 years and expectations are that there should be no problems for at least 25 years. This is based on normal wear and tear, and maintenance schedule being followed. Polyester powder coating has been available for the last 25 years or so and it is generally accepted that early installed windows have presented no problems. The polyester powder coating is applied directly to galvanised steel and therefore there should be no chance of rusting from under the coating. If damage is found to the powder coat finish or if a change of colour is required - it can be directly painted over with normal gloss paint after normal decorating preparation (rubbing down to provide a key).

If the windows are site painted and there is no corrosion evident (see "Condition of frame members [rust]" if there is rust evident) there are three options for carrying out redecoration as stated below.

A 1930s Medium Universal vertical pivot window undergoing a full in-situ strip and renovation by SWS.

OPTION 1 (basic redecoration)
The first option would be to carry out a normal re-decoration. This would involve:
• Servicing, easing and adjusting and associated works as outlined in "Operation and distortion of Opening Windows"
• Rubbing down and preparation of frames
• Top-coating (allowing tolerance for the continued operation of opening windows)

OPTION 2 (full in-situ strip and redecorate)
The second option is more expensive but offers much greater value for money during the life span of the window, and will result in frames that may look as good after the works as they did when new. This is an option of particular merit when dealing with buildings that are listed or are of architectural or historical interest. This option involves:

• Fully stripping the window back to the bare steel (whilst still being fitted into the building)
• Treatment of rusting members
• Application of rust inhibitors
• Re-coating
• Optionally introducing silicone draughtproofing
• Optionally applying perimeter mastic sealants

The advantages of this are that:
• The resultant surface finish would be far superior to that after carrying out a normal redecoration
• Access to, and treatments of, bare steel surfaces can be made
• Rust inhibitors can be applied to all surfaces to lengthen the life of the window
• Deep-set rust repairs carried out more successfully

The disadvantages are:
• All glass usually needs to be removed to carry out the frame works, and therefore costs can sometimes be prohibitive, although this is also an advantage as old tired, scratched and discoloured glass would be replaced for new and would blend well with the renovated surface finishes
• Scaffold (if over first-floor level) would be required externally for access, along with the associated costs, licenses, etc.
• Manual stripping of paintwork from steel windows in situ involves the use of electrical needle scalers which can only be used, for Health & Safety reasons, for short periods in a day which may delay on-site programmes
• The operation can also be deemed as noisy works on some sites due to impact tools being used on the frames which are still screwed to the building structure

OPTION 3 (full off-site strip and redecorate)
The third and most expensive option is similar to option 2. However, instead of stripping the frame in situ, the windows would be removed from their structural openings, transported off-site to workshops, and be fully stripped of all paintwork by way of shot/grit blasting before being machine coated with a blast primer for rust protection.

Sympathetic and detailed refurbishment of existing steel windows enhances both aesthetic appeal and lifespan. The advantages over an in-situ strip are:

• The edges of the frames that are fixed to the structural openings would also be stripped, treated and re-coated
• The shot/grit blasting operation evens out, to a degree, surface pitting and unevenness, leaving a superior surface finish
• The process also blasts away surface corrosion much more effectively than manual paint/surface removal
• No programme implications due to limited needle scaler operational times
• No prolonged noisy works on-site as no needle scaler use
• New rust proofed window fixings and coupling bolts would be used when re-fixing
• A much longer life span
• A much better-looking end product almost, if not totally, up to the aesthetic standard of a new window

The disadvantages are that:
• Windows needs to be removed and so alternative opening fillers may be required for weather tightness and security
• Costs are much greater than the other options

Ironmongery on steel windows is predominately brass. Since the 1960s - brass ironmongery has generally been plated in either Satin Chrome Plate or RTD lacquer (also called Roto-Tone-Dark) which is a dark bronze colour translucent lacquer. Before this time, however, the brass ironmongery was not coated and therefore, without proper cleaning, tarnishes to a point that is not cleanable by normal methods. It is also very common for old ironmongery to be heavily painted over when decorators have painted the window frames. Some old ironmongery was also constructed from gunmetal.

In most cases, the ironmongery can be removed from the windows, taken from the site, chemically dipped, stripped down to the original base metal, mechanically polished to a bright surface finish and re-fixed to the original location. This is the preference when dealing with original period ironmongery of ornate design.

Ironmongery should ideally be re-fitted after redecorations (if being carried out) are completed to stop paint being applied to newly refurbished ironmongery. Any remedial refurbishment works that are required to ironmongery can be carried out in off-site workshops.

A lacquer coating should not be applied to newly stripped and polished ironmongery on completion, as it is found that the brass will tarnish under the surface of the lacquer finish and will be impossible to clean off. This is because old brass is porous.

Alternatively, old ironmongery can be replaced with new (see "Replacement of missing or existing defective ironmongery, hinges and pivots').

Generally, the mounting brackets/pins/rests/etc. which attach the ironmongery to the window frames are made from steel and are welded to the frames. These, therefore, are left in place for (if necessary) site decoration by others. Windows should be wired shut whilst ironmongery refurbishment works are carried out off-site.