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    Listed Property Owners

    Listed Property Owners

    Helping to preserve the heritage and charm of your listed property's sash windows

    Making repairs and restorations to listed properties can often be fraught with regulations and restrictions. Ventrolla have over 30 years’ experience working with listed properties and are committed to providing you with the best advice.

    To date over 560,000 buildings in England, Scotland, Wales and Northern Ireland are listed, classified into 9 grades:


    1. Grade I are buildings of exceptional interest accounting for just 2.5% of 500,000 listed in England and Wales.
    2. Grade II* buildings are particularly important buildings of more than special interest and make up 5.5% of 500,000 listed in England and Wales.
    3. The majority of buildings are Grade II listed, these are of special interest warranting every effort to preserve them and encompass 92% of 500,000 listed in England and Wales.


    1. Grade A are buildings of national or international importance, either architectural or historic, or fine little altered examples of some particular period, style or building type accounting for around 8% of 47,000 listed buildings in Scotland. 
    2. Grade B are buildings of regional or more than local importance, or major examples of some particular period, style or building type which may have been altered accounting for around 51% of 47,000 listed buildings in Scotland. 
    3. Grade C are buildings of local importance, lesser examples of any period, style, or building type, as originally constructed or moderately altered; and simple traditional buildings which group well with others in categories A and B, accounting for the remaining 41% of 47,000 listed buildings in Scotland. 

    Northern Ireland

    1. Grade A (Northern Ireland) are buildings of greatest importance to Northern Ireland including both outstanding architectural set-pieces and the least altered examples of each representative style, period and type accounting for just 2.5% of 8000 listed buildings in Northern Ireland.
    2. Grade B+ buildings which might have merited grade A status but for detracting features such as an incomplete design, lower quality additions or alterations. Also included are buildings that because of exceptional features, interiors or environmental qualities are clearly above the general standard set by grade B buildings. A building may merit listing as grade B+ where its historic importance is greater than a similar building listed as grade B, accounting for 5% of 8000 listed buildings in Northern Ireland. 
    3. Grade B (Northern Ireland) are buildings of local importance and good examples of a particular period or style. A degree of alteration or imperfection of design may be acceptable, accounting for the remaining 92.5% of the 8000 listed buildings in Northern Ireland.

    Traditional timber sash & casement windows are an essential feature of a listed buildings character. Therefore it is vital to retain them, not only because of the aesthetic appeal, but because they add value to your property.

    When upgrading or refurbishing your windows most councils and conservation officers would ask that you renovate your windows where possible and economical, saving as much of the original window. Upgrading is nearly always preferable to replacement.

    Benefits of a Ventrolla Sash & Casment Window Repair:


    • Eliminate draughts and rattles 

    • Lower your energy bills

    • Add value to your property

    • Reduce outside noise 

    • Enjoy easy to operate windows

    Our service focuses firstly on timber window repair and secondly on upgrading the performance of the windows. If you own a listed property and are thinking of renovating your period windows we always recommend you speak with your local conservation officer first to check if they require Listed Building Consent or Planning Permission before any work commences. 

     What happens during the renovation process?

    • Sash window units are carefully removed from the window frame.
    • Any decaying timber in the units, frame or sill is routed out to expose the “sound” timber.
    • Occasionally, new timber is spliced in or replaced where the existing timber is beyond repair.
    • Our unique epoxy resin, VR90, is used to fill the cavities and is moulded to match the existing profile of the timber.
    • Sash cords are replaced, pulleys serviced and the sashes correctly balanced to ensure smooth operation of the windows.

    The sash windows are then upgraded by fitting the Ventrolla Perimeter Sealing System, which virtually eliminates draughts and rattles. At the same time, the Ventrolla Sash Removal System can also be fitted to ease future painting, cleaning and maintenance.

    For more help and information on your listed property and double glazing go to (the society for protection of ancient buildings) or (the listed property owners club). To find your local council visit

    Our projects range from small domestic houses to large commercial projects. However diverse the scale of our activities may be, Ventrolla’s principles have never changed – restoring the original beauty of your sash windows, while improving their performance.

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