Maintaining our own heritage: Practical Conservation Advice – Part 1

Clair Shields – Planning Officer (Building Conservation)

One of the most common enquiries we get regarding old buildings in the National Park is about replacing historic windows in people’s homes, because of natural timber decay. People are concerned that repair would be unfeasible, not worth the bother and/or too expensive.

However this is a general misconception. Windows are made from a variety of materials but the most common is still wood which, if well maintained, can provide a long lifespan as windows can be repaired by replacing individual elements without having to replace the entire sash, or worse, the entire window. So with timber windows it is far less costly to repair what there is rather than replace because this selective repair approach can be taken, and the non damaged elements of the window can be re-used.

For instance, older windows can contain distinctive mouth-blown glass which ripples and distorts reflections, and interesting mouldings and details which may be unique and difficult to reproduce.

Generally repair makes better economic sense and can still be sustainable. Older windows can be made thermally efficient by the retro-fitting of integral draught seals or the use of shutters or secondary glazing.

By retaining the historic timber – which can be of better quality than modern timber due to originating from larger, slow-grown trees – and by retaining the original (or historic)  feature which contributes so much to the appearance of the building and its locality – the special qualities of the North York Moors built environment can be conserved.

Windows are fundamental to the look of many buildings. The loss of traditional windows pose a threat to our local heritage, as it seems windows are now at greater risk than ever from replacement or unsuitable adaptation. The effect will be a cumulative decline of local character.

So below are a series of pictures showing a typical window repair and the extent of timber replacement which can be carried out whilst still retaining historic integrity – in order to give an idea of the level of repairs which can be feasibly undertaken.

Window before repair work commences – window sills, bottom rail and lower frames are decayed. Many owners would now look to replace the whole window. However the most common area of decay is often the bottom rail and sill where water gathers – and in this case the remaining areas of timber are still in sound condition.

By cutting out the decayed areas of timber, and carefully removing the cylinder glass (supporting the frame with a batten), new timber can be spliced in and the glass reinstated.

With the timber spliced in it can be traditionally jointed and the mouldings replicated. All that is left to do here is to re-point around the window using a natural lime mortar.

Traditional windows repaired and repainted. The characterful windows of the building are secured for many more years.

English Heritage have recently published new guidance on the care, repair and upgrading of both timber and metal windows. The guidance is aimed at building professionals and property-owners. It sets out to challenge many of the common perceptions and misconceptions about older windows and explains the history of windows over centuries of technical development and fashion. Detailed technical advice is also provided on maintenance, repair and thermal upgrading as well as restoration.