Maintaining Timber Windows
A well-maintained wooden window is a crucial component of a historical building. It illustrates in varying degrees the materials and technologies design, craftsmanship and aesthetics of the time from which it originates.
If possible, repairs should be made on-site. Proprietary resin-based repair systems can be used to fix the most damaged areas of decay without removing the entire window.
Durability
Timber windows were built to last for hundreds of years. They do require maintenance to keep them looking good. Maintenance tasks include repairs to sash cords as well as tightening the pulleys for sash and painting. There is a growing need for upgrading timber windows to increase the efficiency of energy. This can involve replacing old glass units, fixing the window rebates that are in place, or installing new cills for improved air sealing.
One of the major issues with traditional windows is damage caused by the corrosion of the paintwork. This is particularly important in the case of sash windows as the gaps between sashes can often be extremely large. In these circumstances, water can penetrate the paint film and cause rotting of the putty and the wood underneath. Poor weather conditions can exacerbate the rotting. To stop this from happening, windows should be painted regularly with an exterior wood paint.
Corroded areas should be repaired with resin-based products. This will ensure that the best possible amount of the original fabric remains. It is also essential to minimise the number of holes drilled into the frame to allow cable entry, as they could allow water in and cause decay.
Another significant problem with older windows is structural movement in the wall, which can lead to deformation of the frame and sash. This could result in sash not fitting correctly and jamming or sticking into the opening, and broken glass. This is often corrected by fitting new sash frames made of slow-grown deal (pine), or oak. The cill should be constructed of a strong hardwood like oak, to avoid differential movement between new and older work.
To reduce the risk, there are now a variety of companies that manufacture Boston pattern wooden sash that will fit into the majority of existing openings. These sash come in various sizes and finishes that will fit the needs of modern homeowners. Combined with quadruple draught strips and better thermal insulation these new sash can make a substantial difference to the energy efficiency of your home.
Aesthetics
Many old timber windows have a high aesthetic value since they usually demonstrate, in a way the materials and techniques and architectural taste of the time in which they originate. They may also have significant historical significance in their own right. This is especially true for windows that were unglazed in the early days of timber framed buildings which were just a collection of openings within the frame, which were divided horizontally into mullions, and vertically into wood or iron bars to deter invaders.
Traditional window joinery made of timber can be a stunning element of a structure and is essential to maintain its appearance. As soon as you notice any signs of decay caused by the penetration of moisture it is essential to stop it. This is best done by applying a thorough coat of paint, particularly in areas where there has already been damage or deterioration. It is advisable to use paints specifically designed to be used as part of the system (primer as well as undercoat, finish and primer) and follow the manufacturer's instructions regarding preparation and the amount of coats required at each stage.
The fungus that causes wet rot is able to spread quickly in old windows made of wood. To stop this from happening, get rid of any rotten or damaged parts as promptly as you are able to. The replacement of rotting wood must be done with care by using a slow-growing deal (pine) and, whenever feasible using the same species as security door repairs cambridge that which is being removed to avoid differential movement between the new and old timbers.
Glass became more affordable and abundant in the late medieval era and into the 17th century. As a result, the glazed openings in timber-framed homes were more elaborate, with moulded mullions and traceries, made of wood and deep projecting cills. The glazing was increasingly set within rebated frames and secured with 'glazing sprigs', rather than into lead cames. This method of glazing not only makes windows less likely to leak and break, but also allows wider sheets of clearer glass to be used than would have been possible without the use of led lights.
Energy efficiency
Traditional timber windows have an excellent energy performance due to their thickness, multi-layer construction and very meticulous attention to detail. The large glass areas, the deep projecting cills and large glazing areas reduce air infiltration. With secondary glazing and draughtproofing, windows can be upgraded to improve their energy efficiency. It is essential to remember that these measures should be taken into consideration when it comes to the overall appearance and integrity of the original windows.
It makes sense to repair or upgrade existing windows, rather than replacing them, especially when the improvements in thermal efficiency can be achieved through simple repairs. The windows of the past often have an historic value that shows a variety of technological advances and changes in architectural style. Many people believe that these windows will need to be replaced in the near future. However, most will last for 150, 200, or even 250 years if you take care of maintenance.
It is important to recognise that the decay problems caused by traditional timber windows can be avoided through regular maintenance and swift repairs. Additionally it is vital to identify damp penetration problems and address them swiftly to avoid serious damage. Early paint deterioration is a major problem since it allows moisture penetrate the wood and cause wet rot. The damage is usually not evident until the paintwork becomes cracking or wavy, but can cause significant structural damage, and could lead to further decay.
A quality paint will prevent moisture penetration. To avoid condensation and mould it is essential to keep the paintwork as clean as you can. Modern synthetic paints could be a problem because they are usually formulated to be water-resistant, and this can lead to the formation of mildew inside the window frame.
The majority of older windows were constructed from sapwood-rich wood. These timbers can deteriorate very quickly when exposed to wet weather, however they can be protected with a thorough preservative treatment before they are put to use. It is also crucial to ensure that the type of wood used is suitable to the site and climate conditions, since these factors can affect the longevity of the joinery. Local window manufacturers have various types of sash timbers that can be made to fit the historic openings. They can be made to the standard Boston pattern dimensions or to specific dimensions that are compatible with the historic architecture.
Maintenance
The life of timber windows can be extended by regular inspection, careful redecoration and prompt repair. The main cause of decay is moisture leaking through deteriorated paint and putty. This can be avoided by careful painting and the use of high-quality wood preservative.
It is crucial that repairs to old sash and casement windows are done correctly and completed with the minimum disturbance. Many traditional timber window designs are repairable without removing the frame, and this approach should be used whenever it is feasible. Paint that is peeling or loose should be removed carefully and sanded lightly to improve the 'key' of the surface and facilitate a better adhesion of the new coating. Care should be taken to avoid stripping old paint layers that could have historical value and if they are present, it is recommended that a study of the paint be carried out.
If a piece of wood has rotted the best option is to remove it and replace it with timber inserts designed to match existing profiles. The inserted wood should also be treated with a wood preserver and the connection between the timber cill and the sub-cill of the masonry should be sealed.
It can be tempting to replace traditional windows with PVC u, especially if the installer offers an 'all-in-one' installation which includes removal and replacement within a single day. It is essential that installers of replacement windows have a deep understanding of the history and design of traditional timber frames. This will enable them to make the right suggestions for energy efficiency improvements and other technical upgrades that won't harm the character of a historic building. Those who provide replacement windows should be registered under a Competent Persons Scheme like as FENSA. This will ensure that replacement windows are deemed to be approved in accordance with Building Regulations as a suitable option. A skilled carpenter can put in PVC-u windows that are suited to the original building's style. This is especially relevant when windows are in listed buildings or conservation areas.