Timber is an excellent material for sash window construction. Wood is scientifically proven to provide very good thermal resistance i.e. it is a very poor conductor of heat, which in sash window construction is a good thing. The durability of timber as a material for window construction is variable. This variability is due to the different types of wood that constitute the overall term ‘timber’. Clearly hard wood would be on the very durable end of the scale where as the cheaper and more easily worked softwood would be on the other, with the variations in softness and hardness of woods spanning the range. The wooden sash window requires regular maintenance i.e. the timber sashes need yearly or at least bi annual painting. As hard wood is highly recommended in the construction of any replacement sash window, it is fair to say that the initial cost of a replacement timber sash window is high. However as you will end up with a long lasting, highly thermally resistant and extremely beautiful addition to your property, wooden replacement sashes can not be over recommended. Another frequently overlooked property of timber sash windows is that they are, by the nature, organic entities in their own right. As they are usually placed in older buildings which are, in turn, comprised of organically based building materials, they blend well with them. Old buildings have a personality of their own. The materials used in their construction react to the atmospheric conditions. Over the centuries the whole gels together into its, own organic entity. When adding any new element to an old building this factor has to be born in mind. With the use of timber you are treating an old building with due respect as you have recognized this subtly and are giving the rest of the structure the chance to settle down with the new addition.
When fitting a replacement sash window it is also important to consider the style of the window. The main choice is between a ‘double hung sash window’ and a ‘single hung sash’. The double hung sash window is the most prevalent. If your building has been subjected to unsympathetic renovations over its’ life time it might be worth doing some research to insure that you are in fact putting in the correct type for you building. The single hung sash window comprises of just one moveable sash, generally the movable part is the bottom sash. In this type of window the upper sash is fixed. This is a cheaper and generally earlier type of sash window construction. The double hung sash window is by far the most common sash window style. The two sashes over lap a the middle of the window. Both sashes can be moved. The choices you will have to make for both types of window are the proportions of top sash to bottom sash. This is very important. Clearly if you are doing only one of many, the style of replacement sash window will be dictated by the existing windows. However if you are replacing all the windows in an old building care should be taken to get the correct style for the period of the house. This will require a little research on your part. After doing your research it is then up to you and your own tastes to decide on the ultimate sash window proportions for your home.