The longevity of renovating timber windows: what you need to know

If you own a historic, heritage or listed property, you will understand how important it is to maintain the original character of the property. A big feature of these properties are the windows – usually traditional timber sash. Over time, the windows can deteriorate from elemental exposure but the question remains – is it better to refurbish the windows or replace them entirely? When considering longevity, cost-effectiveness, and sustainability, the answer overwhelmingly favours renovation and restoration efforts.

Comparing the lifespan of refurbished vs new timber windows

The strength of historic timber

Traditional sash windows were often crafted from slow-grown, high-quality hardwoods such as oak or Baltic pine. This is because these timbers have a naturally high resistance to rot and decay, with many windows surviving for over a century. In contrast, many modern timber replacements use fast-grown softwoods or engineered timber, which can be less durable in the long run. By refurbishing existing windows, you retain the superior quality of historic timber as opposed to replacing it with the newer timber that often has a shorter lifespan. Typically a replacement made with modern timber could start showing deterioration in as little as 15-25 years if regular upkeep is not maintained.

Lifespan of a renovated timber sash window

With expert restoration, a refurbished timber sash window can last another 50 – 100 years, so long as it is well-maintained. The key to longevity lies in:

• Rot treatment and repairs – addressing any areas of decay with specialist epoxy resins or spliced timber repairs, consulting an expert where possible.
• Protective coatings – using breathable, microporous paints and stains to prevent moisture ingress.
• Weatherproofing improvements – upgrading glazing putty, replacing draught-proofing seals, and ensuring proper drainage to prevent water damage.
• Regular maintenance – simple tasks like repainting and lubricating pulleys can extend the window’s life significantly.

Why renovation is the better choice

• Retaining authenticity in heritage properties
  Listed buildings and conservation area properties often require the retention of original features as part of planning restrictions. Renovation allows homeowners to preserve the architectural integrity of their property while ensuring compliance with conservation guidelines and bring properties up to the necessary EPC ratings.

• Cost-effectiveness
  Full window replacement can be costly, particularly if bespoke heritage sash windows are needed. In contrast, refurbishment typically costs a fraction of the price, especially when only specific sections needed repair. Long term, the costs will also be lower due to the longevity of the historic timber over a modern alternative.

• Sustainability and environmental benefits
  Refurbishing existing windows significantly reduces the environmental impact. The carbon footprint associated with manufacturing and installing new windows is far greater than that of careful restoration, especially when traditional techniques are used. Keeping historic timber windows also prevents unnecessary landfill waste and reduces demand for newly harvested timber.

• Improving energy efficiency without replacement
  One of the common arguments for window replacement is energy efficiency. However, a well-renovated sash window can perform just as effectively as a modern alternative. By incorporating discreet draught-proofing, secondary glazing, or slimline double glazing, homeowners can improve insulation while maintaining period charm.

For owners of historic and heritage properties, restoring timber sash windows is more than just a practical choice – it is the best way to honour a building’s architectural past while ensuring longevity and sustainability. A well-maintained, refurbished sash window can outlast a new one, retain superior-quality timber, and offer a more sustainable, cost-effective solution. By choosing restoration over replacement, owners are making an investment in the future of their property, preserving both its character and historical integrity for generations to come.