Maintaining Timber Windows

A well-maintained wooden window is an important component of a historical building. It demonstrates in various degrees the materials and technologies, craftsmanship and architectural taste of the time period from which it dates.

When possible, repairs should be done in-situ. Proprietary resin-based repair systems can be used to fix the most damaged areas of decay without removing the whole window.

Durability

Timber windows were built to last for centuries. They require regular maintenance to ensure they look good. Maintenance tasks include sash cord repairs, retightening of sash pulleys and painting. The demand for enhancing timber windows in order to improve efficiency in energy use is also growing. This may mean replacing old glazing units, repairing the window rebates that are in place or putting up new cills to allow for improved air sealing.

The deterioration of paintwork is a major issue with traditional windows. This is particularly important when windows made of sash are involved because the gaps between sashes can be quite wide. In these cases water can enter the paint film and cause rotting of the wood or putty underneath. The weather can be a factor in accelerating the rotting. To stop this from happening, windows need to be painted regularly with an exterior wood paint.

The areas that are damaged should also be repaired using a resin-based product. This will ensure the maximum amount of original fabric is preserved. It is also essential to minimise the number of holes drilled into the frame for cable entry, as they could admit water and lead to decay.

Another major issue with older windows is structural movement in the wall, which can cause deformation of the frame and the sash. This could result in sash not fitting correctly, jamming or sticking in the opening, or breaking glass. Often this can be corrected by the fitting of new sash boxes constructed from slow-growing deal (pine) or oak. The cill must be made from a sturdy hardwood, like oak, to prevent shifting between the new and old work.

There are a variety of companies that manufacture Boston pattern wooden sash that fit most existing openings. The sash is available in a variety of sizes and finishes to meet the needs of today's homeowner. In conjunction with quadruple draught strip and better thermal insulation these new sash options can make a substantial difference to the energy efficiency of a home.

Aesthetics

Many old timber windows have a great aesthetic value as they often demonstrate, in a way the materials and technologies and architectural style of the time from when they were built. They may have significant historical significance as a set. This is particularly true of early unglazed windows in timber-framed buildings, where the majority were simply a series of openings within structural frames that were subdivided horizontally by mullions and vertical wood or iron bars in order to keep out intrusions.

Traditional timber window joinery can be a stunning aspect of a building, and is essential to keep its appearance. It is crucial that any decay caused by moisture penetration should be stopped as soon as it is recognised. This is best done by painting thoroughly, especially in areas where there has already been damage or degradation. It is recommended to use paints that are specifically designed to be used as part of the system (primer as well as undercoat, finish and primer) and follow the manufacturer's guidelines in relation to preparation and number of coats needed at each stage.

The fungus that causes wet rot can quickly spread in old timber windows. To prevent this, get rid of any rotten or damaged parts as quickly as you can. Replace rotting wood with slow-growing deal (pine) and, if possible, the same type of wood that is being removed to prevent any differential movement.

Glass became cheaper and more abundant in the late medieval era and into the 17th century. As a result, double glazed door repairs openings on timber-framed houses became more complicated with moulded mullions and traceries, made of wood and deep projecting cills. In recent years, glazing was fixed into rebated frames with glazing sprigs, not lead cames. This method of glazing is not only less prone to leaks but it also allows more expansive, clearer sheets of glass to be used in windows than would be possible without the need for lead lights.

Energy efficiency

Traditional timber windows have an excellent energy performance due to their thickness and multi-layer construction. They also pay attentive attention to detail. The large glass areas, deep projecting cills and large glazing areas help to reduce air infiltration. Windows can be designed to improve their energy efficiency through draughtproofing and secondary glazing. However, it is important to keep in mind that any such measures should be evaluated in the context of the overall quality and appearance of the window in its original form.

It is sensible to repair or upgrade existing windows that are older rather than replacing them, especially when the improvements in energy efficiency can be made through simple repairs. Older windows typically have a historical value that demonstrates a range of technological advancement and changes in architectural style. Many people believe that the windows will need to be replaced in the near future. However, they will last for 150,200, and even 250 years with proper maintenance.

It is crucial to understand that decay issues associated in traditional timber windows are avoidable with quick and thorough repairs. It is also important to recognize damp issues and address them promptly so that you can avoid serious damage. Early paint deterioration can be a problem because it allows moisture to penetrate into the wood, causing wet rot. It is not uncommon for this type of damage to go undetected until the paintwork begins to crack or become wavy. However, it could cause structural damage and then further decay.

A high-quality paint will prevent this moisture from entering. It is also essential to keep the paintwork in good condition in order to prevent condensation and mould growth. The use of modern synthetic paints can be problematic since they are typically designed to be water-resistant which can lead to the formation of mildew in the window frame.

The majority of older windows were constructed from timber with a high proportion of sapwood. The timbers will deteriorate rapidly if exposed to rain, but they can be preserved with an extensive preservation treatment prior to use. It is essential to select the appropriate type of wood for the site and climate, as these variables can affect the durability of the joinery. Local window manufacturers have an array of sash made from timber that can be made to fit the historic openings. They can be built according to the standard Boston pattern dimensions, or to custom sizes that are in keeping with the architectural style of historic buildings.

Maintenance

The life of timber windows can be extended considerably through regular inspections carefully redecoration, and prompt repair. The primary cause of wood decay is moisture penetration through the deteriorated paint and putty. This can be prevented by using a good wood preservative and thoroughly painting the wood.

It is crucial that repairs to old sash and casement windows are well executed and done with minimal disruption. It is possible to repair the majority of traditional wooden window designs without having to remove the frame. This should be done whenever possible. Peeling or loose paint should be removed with care and lightly sanded to improve the key of the surface and allow for a better adhesion of the new coating. It is important to avoid removing old paint layers, as they may have historical value.

If a portion of wood is decayed the best option is to take it off and replace it with timber inserts shaped to match existing profiles. The timber that is inserted should be treated with a wood preservative, and the joint between masonry sub-cills and timber cill should be sealed.

It is tempting to replace traditional windows with PVC u, especially when the installer offers an all-in-one installation that includes both replacement and removal in one day. It is, however, essential that the person installing replacement windows has a complete understanding of the construction and history of traditional timber frames. This will allow them to make the appropriate suggestions for energy efficiency improvements and other technological advancements that won't harm the character of a historic building. Window Weatherstripping replacements should be registered with a Competent Persons Scheme such as FENSA. This will ensure that the replacements are approved as a suitable solution under Building Regulations. It is, of course, possible for an experienced and skilled carpenter to install PVC-u windows that fit the the building originally. This is especially applicable when windows are located within listed buildings or conservation areas.