Maintaining exterior woodwork on buildings, particularly windows, has not always proved to be easy.

Exposure to the elements, including ultra violet light and rain, can lead to blistering and flaking of coatings and leaky joints if maintenance is not carried out correctly or at the appropriate time.

Of course, if the quality of the joinery is not great in the first place then the job of maintenance is made even more difficult. Some examples of inferior workmanship coupled with insufficient coating specification and application have caused the reputation of timber windows to suffer.

But it looks like things are changing.

One of the main players in the coatings market, Akzo Nobel Woodcare, which manufacturers the Sikkens and Sadolin ranges, is promoting its Sentinel Plus Wood Protection Programme.

Its seeds are to be found in the Sikkens Maintenance Scheme, which began in 1949 with the planned maintenance cycles of the exterior woodwork of 1,200 houses in Amsterdam. The scheme is popular in Europe, especially France, Holland and Germany.

In 1999, Sikkens decided to market the scheme in the UK and renamed it the Sentinel Wood Protection Programme.

Akzo Nobel’s joinery specification manager Tony Alderson said: ‘Because of compulsory competitive tendering, planned maintenance cycles with long-term cost savings were not always considered. The benefits to the property owner are of significant importance. We felt that by promoting the scheme, we could contribute to raising the profile of timber.’

Best Value procurement

Legislation introduced last year demands that local authorities must specify to Best Value procurement methods, which means adopting principles from the Egan Report. This entails taking into consideration the whole life cost of the building and its impact on the environment, rather than just the one-off initial costs of buying components.

‘There is a big swing to timber now because of environmental pressures and the Egan Report. The Egan Report is making the whole industry talk,’ added Mr Alderson.

Such a sea-change in attitudes has created a captive audience for the Sentinel scheme.

For Akzo Nobel it became increasingly clear that some kind of control had to be brought to the coating process.

Mr Alderson said if coatings were not applied correctly to a component of good design, then a low maintenance system would not be achieved.

‘The only way we could seriously contribute to the performance of the coating and performance of the window was to form a partnership with certain high quality window manufacturers who produced joinery of a good design with coating systems applied in controlled factory conditions with application of a more cost-effective high film build and assurance of a sufficient coating film all round the substrate. Problems associated with site glazing and painting are thus overcome.’

The Sentinel Plus 25-year maintenance programme was launched in 2000.

Technical consultants from Akzo Nobel Woodcare work closely with the architect and specifier promoting the benefits of factory finishing and will determine the specification requirements such as site exposure and location, performance requirements and the maintenance schedule needed to achieve a low-cost, one coat redecoration with a Sikkens site-applied coating onto fully factory finished joinery.

Projects are then tracked through the Sentinel Plus database to ensure maintenance is carried out at the appropriate time. Maintenance managers in charge of buildings are then contacted six months before maintenance is due.

The aim is to keep long-term maintenance costs down and extend the lifespan of the joinery, resulting in lower energy consumption and waste compared with non-factory finished windows and those made from alternative materials.

Mr Alderson added: ‘At the end of the day we are paint manufacturers. What we are doing is giving a better foundation for our site applied products. Application on building sites has serious limitations for long-term performance. If you take a base-stained window it’s good for about three months unprotected. Windows should be stored under cover and ventilated, but at new build housing developments you see a base-stained window with mortar all over it. It’s completely abused.’

Commitment to timber

Akzo Nobel’s commitment to timber windows was demonstrated by its creation of the British Advanced Joinery Systems (BAJS) window accreditation scheme in 1995. This was taken over by the British Woodworking Federation in 1997 and became the well-known and highly successful BWF Timber Window Accreditation Scheme.

Spalding-based bespoke window manufacturer George Barnsdale & Sons is one of the Sentinel Plus members.

Its managing director Duncan Wright said: ‘Somebody sticks a window in a hole and then someone else has to pick up the pieces. With this scheme it means that someone is going to get a call about maintenance.’

Participation in the scheme has not changed Barnsdale’s production process – its windows were already treated with Akzo coatings – but Mr Wright said that though the scheme was in its early days, he thought it would make a difference to his business in the medium and longer term. He thinks housing associations will be very keen.

‘Sentinel is much peace of mind for our customers for the future. From our point view it helps us promote the whole package. It adds to the value of our package without costing anything and does help the industry.

Mr Wright said Barnsdale was very busy at the moment, extending lead times and wanted to increase capacity. ‘There is a real swing back to timber windows,’ he added.

Jayne Taylor, Akzo’s senior brand manager for joinery coatings, said housing associations and local authorities were already showing a lot of interest in Sentinel Plus.

‘The most difficult area to convince of the benefits of timber is the domestic end-user. I believe that many still see advantages of alternative materials over timber.’

She feels this may change when fully factory finished and glazed timber windows become more accessible to the public and are sold off the shelf in builders merchants

‘We have to accept we are not going to convince everybody. Having said that, excellent strategies like Wood for Good are certainly helping to push timber,’ she added.

She believes properly treated timber windows can ‘definitely’ outperform PVCu.

‘After all, the only window with an established history is the timber window. Many windows in buildings today are over 100 years old and we see no reason why this can’t be achieved today providing appropriate maintenance is adhered to. As an industry we need to concentrate our efforts to promote the benefits of timber windows, not slate PVCu. The way forward now is for joinery window manufacturers now is to up the quality of their design. Over recent years, the growth of PVCu has slowed and in some areas, particularly the public sector, is beginning to decline. And timber windows are also starting to get back into the private sector.’

Ms Taylor feels there may be a lack of understanding in the architectural industry about what can be achieved with correct design detailing, but Sentinel Plus has allowed Akzo to speak to architects at an early stage and enter into their decision-making. She has high hopes for the timber and Sentinel Plus.

‘For many homeowners, the south facing garden and open log fires are important criteria and the ultimate aspiration when buying a home. We would like to think that the timber window would be a symbol of aspiration.’