A well-maintained window made of timber is a significant element of the historic fabric of a building. It demonstrates in various degrees the different materials and technologies as well as the craftsmanship and architectural style of the period from which it originates.
If repairs are possible to windows that are already in use should be made in situ. Repairing the most severe areas of decay is possible with the help of specialized resin-based systems.
Durability
Timber windows were built to last hundreds of years. They do require maintenance to ensure they look good. The most common maintenance tasks include sash-cord repairs as well as tightening sash pulleys and painting. There is also a growing demand to upgrade timber windows to increase energy efficiency. This can include replacing old glazing units, fixing the window rebates that are in place or installing new cills to improve air seal.
https://www.repairmywindowsanddoors.co.uk/cambridge-windowrepair/ of the main issues with traditional windows is the damage caused by corrosion of the paintwork. This is especially true when sash windows are concerned because the gaps between sashes can often be very large. In these instances, water can penetrate the paint film and cause decay of the putty and the wood underneath. Poor weather conditions can exacerbate the decay. To stop this from happening, windows must be regularly painted with an exterior wood paint.
In addition to repainting, corroded areas must be repaired using a resin-based repair product. This will ensure that the maximum amount of original fabric is retained. It is crucial to reduce the number of holes that are created into the frame in order to allow cable access, as these can admit moisture and cause decay.
Another issue with older windows is structural movement in the wall, which can cause deformation of the frame and sash. This can result in the sash not fitting properly and jamming or sticking to the opening and cracked glazing. This can often be fixed by the fitting of new sash boxes made from slow grown deal (pine) or oak. The cill should be made from durable hardwood such as oak to avoid differential movement between the old and new work.
There are now several companies that manufacture Boston pattern wooden sash that fit in with the majority of openings. The sash is available in a range of sizes and finishes that meet the requirements of the modern homeowner. Together with quadruple draught strips and improved thermal insulation, these new sash options can make significant improvements to the energy efficiency of a house.
Aesthetics
A lot of old timber frames have a high aesthetic appeal, as they show, in some form, the materials technology, the construction process, and the architectural style of the time they were built. They may also have significant historical value on their own. This is particularly true of windows that were unglazed in the early days of timber-framed structures, where the great majority were merely a series of openings within the structural frame sub-divided horizontally into mullions and wood or iron bars to keep out invaders.
It is important to maintain the appearance of traditional wooden window joinery. As soon as you see any decay caused by the penetration of moisture it is crucial to stop it. This is best accomplished by a thorough painting process, especially in areas in which there is already damage or degradation. It is recommended to use paints that are designed to be used as part of the system (primer as well as undercoat, finish and primer) and follow the manufacturer's instructions in relation to preparation and the number of coats required at each stage.
The fungus that causes wet rot can spread quickly in old timber windows. To prevent this from happening, take out any rotten or damaged parts as soon as you can. The replacement of wood that is rotting must be done with care by using a slow-growing deal (pine) and, wherever possible using the same species as which is being removed to prevent any movement differences between the new and old timbers.
Glass became cheaper and more abundant in the late medieval period and into the 17th century. In the process, the glazed openings in timber-framed homes became more complicated with moulded mullions, wooden tracery and cills that protruded deep. In the past, more often, the glass was placed within frames with rebates and pinned in with 'glazing sprigs' rather than being inserted into lead cames. This method of glazing not only makes the windows less likely to leak and break, but also allows wider sheets of clearer glass to be employed than would be feasible without the use of leaded lights.
Energy efficiency
The traditional timber windows are energy efficient due to their thickness and multilayer construction as well as attention to particulars. They also feature large glass areas as well as deep projecting cills that reduce air infiltration. The windows can be made to increase their energy efficiency through draughtproofing and secondary glazing. It is essential 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.
It makes sense to fix or upgrade historic windows rather than replace them, especially when the improvements in thermal efficiency can be made by simple repairs. Older windows are usually of historical significance, since they reflect a variety of technological advancement and changes in architectural taste. Most people assume that these windows will have to be replaced in the near future. However, most are still in service for 150, 200 or even 250 years if they are maintained with proper maintenance.
It is crucial to understand that decay issues with traditional timber windows can be easily prevented with prompt and thorough repairs. In addition it is vital to spot damp penetration issues and address them swiftly to avoid major damage. Early deterioration of paint is a particular problem, because it allows moisture to penetrate the wood and cause wet rot. This damage is often not apparent until the paintwork becomes wavy or cracked however, it can cause serious structural damage and lead to further decay.
A good quality paint will prevent this moisture penetration. It is also necessary to keep the paintwork clean in order to prevent condensation and mould growth. Modern synthetic paints pose a challenge since they are usually water-resistant, and can cause mildew to develop within the window frame.
The majority of windows from the past were constructed from sapwood-rich timber. These timbers are susceptible to deterioration rapidly if exposed to wet weather conditions, but they can be protected by a thorough treatment of preservative before they are used. It is important to choose the appropriate type of wood for the site and climate, as these factors will affect the durability of the joinery. Local window manufacturers provide various types of sash made from timber that can be adapted to fit historical openings. They can be built to the standard Boston pattern dimensions, or to custom sizes that are in keeping with the architectural style of historic buildings.
Maintenance
The life span of windows made from timber can be extended considerably by regular inspection carefully redecoration, and prompt repair. The main cause of decay is moisture infiltration through deteriorated putty and paint. This can be avoided by using a good wood preservative and painting the wood thoroughly.
It is essential that repairs to the old sash and casement windows are properly executed, and carried out with minimal disruption. A lot of traditional wooden window designs are repairable without removing the frame, and this option should be used whenever it is possible. Remove peeling or loose paint and then lightly sand the surface to improve the "key" of the surface. This will allow the new coating to adhere better. Be careful to avoid stripping paint layers that may have historic value and if they are present it is recommended that a paint analysis be carried out.
When a piece of wood has begun to decay, the best option is to take out the rotten material and replace it with spliced-in timber inserts that are shaped to fit the existing profiles. The timber inserts should be treated using wood preservative, and the joint between masonry sub-cill and timber cill should be sealed.
It can be tempting to replace traditional windows with PVC u, particularly if the installer offers an 'all-in-one' installation which includes removal and replacement in a single day. It is, however, essential that the person installing replacement windows has a full knowledge of the structure and history of traditional wooden frames. This will allow them to make appropriate suggestions for energy efficiency improvements and other technological upgrades that won't harm the character of a historic building. Those providing replacement windows should be registered with a Competent Persons Scheme like FENSA. This will ensure the replacements are deemed acceptable by the Building Regulations as a suitable alternative. It is, of course, possible for a skilled and experienced carpenter to install PVC-u windows that are sympathetic to the style of the building originally. This is especially true where the windows are located in listed buildings or conservation areas.
