Wooden Timber Windows, Doors and Stairs
High Quality, Long Life, Bespoke
Research & Development
George Barnsdale have been making timber windows for over a hundred years. Many are still in use. Why then have so many windows made in the 70's and 80's failed so quickly?
Our research has looked at the old and modern methods and we have developed our products to get the best from both.
What have we looked at?
Timber
We have to use timber that is naturally durable, will allow the coatings to perform well and come from sustainable sources. We have researched windows that have lasted well. Almost all of then have durable hardwood cills with redwood heartwood for everything else. More information.
Preservation
The only preservative applied to windows in the past was lead based paint. This proved very successful but is unacceptable now. We are making our windows to last well in excess of 50 years and as organic based preservatives are unlikely to remain stable for that period we have researched the use of boron based preservative and
the results show that
it is the best material currently available and as it is a natural material, less likely to cause environmental damage. See Borax for more information. We are also involved with a joint European project that is looking at high temperature treatment with modified linseed oil. This may result in exciting new methods.
Joint Design
Window joints were traditionally mortice and tenoned. Prior to assembly the end grains and the mortice holes were soaked in lead based primer, assembled and wedged. This method was replaced with glued comb joints which has been a major cause of failure. In 1989 Barnsdale won a substantial DTI Smart Award to look into joint design. We are still researching new methods but have concluded that if a liberal coating of resorcinol formaldehyde is applied to the end grains and the joint long term performance is extremely good.
Glazing
Failure of double glazed units, glazing beads and joints have been a major problem. Our research has centred on reducing the exposed timber beads and reducing the exposure of the units sealant to moisture. Our internally beaded drained and ventilated system has proved to be very satisfactory.
Coatings
If the coating of a window remains intact a well made timber window will last indefinitely. We have carried out extensive work on the overall design of the window to allow the coating to perform well and on the coatings themselves. As a result of this we saturate the assemblies in primer, apply a mid coat and then a top coat of a different colour. As the coating erodes it will finally expose the mid coat which will indicate recoating is required.
Partners in research
A J Charlton & Sons Ltd
Foreco Dalfsen BV Dalfsen, Holland
SHR Timber Research, Holland
BRE (Building Research Establishment) Garston and East Kilbride
British Woodworking Federation, London