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    Average cost of sash windows

    Summary: How much do sash windows cost, average sash window installation costs and average price to repair a sash window.

    Beautiful hardwood sash windows are often a sought after feature of period homes, but whether you are fitting them for the first time, or renovating or replacing them altogether, there are many things to consider. A sash window is made up of many components. Firstly, it may have one or more movable parts that form the frame that holds a pane of glass in place. Secondly, to aid operation the weight of the glass is counterbalanced by a weight that is concealed within the frame; this connects to the window via a sash cord that runs over a pulley. In general, good, well fitting windows need to be worked on individually and benefit from a bespoke rather than a mass produced service. Modern sash windows enable you to have a high standard of durability and thermal efficiency with the minimum of maintenance.

    Average cost


    Average cost



    Sash windows (Labour & materials) £100 - £500 (Per window) 2012 Get quote

    Factors to consider

    All listed buildings require listed building consent for replacing sash windows. If your property is Grade II you generally have more flexibility than if your property is Grade I, however it is imperative to note that it is a criminal offence to carry out work that needs consent, before that consent has been obtained. Listed building planning consent requires more detailed plans to be submitted than normal planning. You may even need to submit samples of glazing or wood to the planning department for consideration.

    The requirements of old windows will vary not only from property to property, but also from window to window on the same property. Many people would recommend restoring any damaged sash windows back to the original wood, as replacing a sash window with UPVC can lower the value of a period property. Any period window should be restored or replaces using a design which is sympathetic to its architectural heritage. Also, restoring often works out cheaper than replacing with new windows. Whether you do the work yourself, or employ a specialist window company or joiner, you need to ensure you are doing the best to reduce rattles and draughts, one of the biggest complaint from sash window owners. Heat efficiency is paramount, ensuring you have the best heat retention in rooms, which in turn will reduce heating costs. Noise reduction, through glazing or through seals, will be beneficial to consider too. In this day and age the security of the window will need to be addressed, which locking systems you will use to provide maximum peace of mind.

    If you are replacing the glazing of any current window, or having a brand new window, it is essential that you comply with current thermal performance standards (L1). Also, you will need to comply with building regulations regarding glazing safety (N1) which looks at minimizing the risk of injury from breaking or falling glass. A legislation that is unique to sash windows (K2) is that any replacement sash window that is above ground level must be fitted with restrictor stays to prevent accidental falls from the window. To prove this you will have to obtain a certificate of compliance from Local Authority Building Control or from FENSA. If you are using a contractor this will also mean that they must offer you insurance against any breach in this standard due to their work.

    All listed buildings require listed building consent for replacing sash windows.

    Restoring often works out cheaper than replacing with new windows.

    Double or triple glazing can help keep the home energy efficient.

    Costs to consider

    If you have pre-existing sash windows that need work then the following all need to be looked at to ensure the window is in full working order:

    • Reconditioning the sash box or casement.
    • Replacing damaged sills.
    • Replacing glazing.
    • Putting in new draught strips.
    • Replacing sash cords.
    • Adjusting and servicing of weighting mechanism.
    • Renewing sash joints.
    • Refitting of sash.
    • Replacing the brass catch.
    • Converting the window to double glazing.

    If you intend doing the work yourself it is possible to pick up kits that provide all the specialist equipment you will need to renovate or fit a sash window, such as beading, cord and seal. In addition you will need protective clothing, dust sheets and the normal array of tools owned by any proficient DIY'er. A Power planer and sander may also come in useful and additional sash weights may also be needed. Finally, materials for the finish such as epoxy filler, primer, undercoat and gloss paint will all have to be factored in.

    Obviously if you choose to use a speciality window company or joiner to carry out the work on your behalf, you will need to factor in the additional costs of paying their labour over and above your materials costs.

    Replacing a sash window with UPVC can lower the value of a period property.

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