Maintaining Timber Windows
A well-maintained wooden window is an important element of a building that is historic. It reflects in different levels, the materials and techniques of the time it was constructed, the architectural style and craftsmanship.
When possible, repairs should be made in-situ. Repair systems made of resin can be used to repair the most deteriorated areas without removing the whole window.
Durability
Timber windows were built to last hundreds of years. However, they need to be maintained to ensure they look good and functioning correctly. Maintenance tasks include sash cord repairs and retightening sash pulleys and painting. There is a growing need to upgrade timber windows to increase energy efficiency. This could mean replacing old glass units, fixing existing window rebates or putting up new cills to allow for improved air sealing.
The deterioration of paintwork is a major problem with traditional windows. This is particularly important when it comes to sash windows because the gaps between sashes can often be extremely large. In these instances water may get through the paint film and cause rotting of the putty as well as underlying wood. The rotting process can be made worse by weather conditions that are not ideal. To prevent this from happening, windows must be painted regularly with an exterior wood paint.
Areas that have been damaged must be repaired using a resin-based product. This will ensure that the maximum amount of original fabric retained. It is important to minimize the number of holes created into the frame to allow cable entry, because they could let in moisture and cause decay.
Another issue with older windows is structural movement in the wall, which could cause deformation of the frame and sash. This can lead to sash no longer fitting correctly and jamming or sticking to the opening, and damaged glazing. Most often, this is corrected through the installation of new sash boxes that have been constructed from slow-growing deal (pine) or oak. The cill should be constructed from durable hardwood such as oak to prevent movement between the existing and new work.
There are several companies that produce Boston pattern wooden sash to fit in with the majority of openings. These sash come in a variety of sizes and finishes that suit the needs of modern homeowners. Combined with quadruple draught strips and better thermal insulation these new sash options can make an enormous difference to the energy efficiency of a house.
Aesthetics
Many old wooden windows have an excellent aesthetic value because they typically demonstrate, in a way, the materials and technology and architectural style of the period from when they were built. They could also have a significant historic value in their own right. This is especially true of early unglazed window openings in timber-framed structures, where the great majority were just a collection of openings within the frame that were subdivided horizontally into mullions and iron or wood bars to deter intrusions.
It is important to maintain the appearance of traditional wooden window joinery. It is crucial that any decay resulting from water penetration is removed as soon as it is discovered. This can be done by painting thoroughly, especially in areas where there has already been damage or degradation. It is recommended to use paints specifically designed to be used as part of a system (primer, undercoat and finish) and follow the manufacturer's instructions in terms of preparation and number of coats needed at each stage.
The fungus that causes wet rot can spread quickly in old timber windows. To prevent this, remove any rotten or damaged parts as quickly as you can. The replacement of wood that is rotting should be carefully undertaken by using a slow-growing deal (pine) and, if possible, the same species as which is being removed in order to prevent any movement differences between the new and old timbers.
Glass became less expensive and more abundant in the late medieval era and into the 17th century. This led to the glazed openings in timber-framed homes were more elaborate, with moulded mullions and traceries, made of wood and cills that protruded deep. The glazing was increasingly laid within rebated frames and pinned in by 'glazing sprigs' rather than into lead cames. This method of glazing not only makes the windows less likely to leak and also allows more clear glass sheets to be employed than would be feasible without the use of leaded lights.
Energy efficiency
Traditional timber windows are energy efficient because of their thickness, multilayer construction and care for detail. They also feature large glass areas as well as deep projection cills which reduce air infiltration. The windows can be modified to improve their energy efficiency with draught-proofing and secondary glazing. It is important to keep in mind that these measures need to be taken into consideration in relation to the overall appearance and integrity of the original windows.
Therefore, keeping old windows that require repair instead of replacing them is logical particularly when thermal enhancements can be achieved economically through simple repairs and improvements. The windows of the past often have historical significance that illustrates a variety of technological advances and changes in architectural tastes. Many people believe that these windows will have to be replaced in the near future. However, most will last for 150, 200 or even 250 years with proper maintenance.
It is important to recognize that decay problems with traditional timber windows are preventable by prompt and thorough repairs. It is also crucial to recognize damp issues and correct them swiftly to avoid major damage. Paint deterioration that occurs early is a concern because it allows moisture to penetrate into the wood, causing wet rot. This damage is often not apparent until the paintwork is cracking or wavy, but can cause significant structural damage and can lead to further decay.
A high-quality paint will stop this moisture from entering. It is also essential to keep the paintwork spotless to avoid condensation and mould growth. Modern synthetic paints pose a problem since they are usually water-resistant and may cause mildew growth within the window frame.
The majority of older windows were constructed from timber with a high proportion of sapwood. These timbers deteriorate quickly if exposed to rain, however they can be preserved with a thorough preservation process prior to use. It is also important to ensure that the kind of wood used is suitable to the location and climate conditions, as these elements can affect the longevity of the joinery. Local window manufacturers produce a variety of timber sash that can be adapted to fit specific 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
Regular inspection, careful redecoration, and quick repairs can prolong the lifespan of windows made of timber. The most common reason for decay is moisture intrusion through the deterioration of paint and putty. This can be avoided with thorough painting and using a good quality wood preservative.
Repairs to sash windows that are old and casement window frames should be handled with care and minimal disruption. Repairs can be made to many traditional timber window designs without removing the frame. This should be done whenever possible. Peeling or loose paint must be removed with care and sanded lightly to improve the 'key' of the surface and allow for a better adhesion of the new coating. Be careful to avoid stripping paint layers that may have historic value, and where these are present it is recommended that a study of the paint be conducted.
If a piece of timber has sash window repair cambridge begun to decay, the best way to proceed is to remove the rotted material and replace it with spliced-in inserts that are shaped to match existing profiles. The inserted timber should also be treated with a wood preservative and the junction between masonry sub-cill and timber cill should be sealed.
Replacement of traditional windows with PVC-u can be a tempting option, especially when the installer offers a 'one stop shop' installation that takes care of removal and replacement in the span of a 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 appropriate suggestions for improvements to energy efficiency and other technological upgrades that won't harm the historical character of a building. Those who provide replacement windows must be registered under a Competent Persons Scheme like as FENSA. This will ensure that replacement windows are deemed acceptable by the Building Regulations as a suitable option. It is quite possible for an experienced and skilled carpenter to install PVC-u windows that are sympathetic to the character of the original building. This is particularly true when the windows are in conservation areas or listed buildings.