The Timber in Timber Windows
All of the timber that George Barnsdale use to manufacture timber windows and doors is available with FSC® Chain of Custody to ensure that it has been sustainably sourced.
Timber falls into two categories – Softwood and Hardwood. This has nothing to do with the durability of the timber, some Hardwoods are brittle and soft such as balsa wood, and some Softwoods are very strong. The terminology comes from the type of tree, Hardwood comes from deciduous trees (trees that lose their leaves) and Softwood comes from trees that keep their leaves all year round.
Our standard timber windows and doors range is actually made up of a mix of three different timbers – Redwood WoodHeart, Accoya.
George Barnsdale have invested heavily in research and development into suitable timbers which has resulted in this combination of timbers which offers the best quality and performance whilst still remaining cost effective.
Redwood WoodHeart® is the heartwood taken from Nordic Scots pine trees and is used for all our standard frames and window sashes. By using this heartwood (the centre of the log) we get very good durability and dimensional stability, as well as very good thermal performance.
The reduced moisture uptake and increased stability of the timber produces a substrate which enhances the coating life span (this is key to a long life window or door, because if the coating remains intact the window or door will last indefinitely).
The timber is x-ray selected and any defects such as knotting, twists and shakes are cut out and then the timber is re-joined using a finger joint, which is stronger that then timber itself.
Accoya® is exceptionally stable and is classed as a modified timber. This modification process involves impregnating the timber with acetic anhydride by placing dried timber into large autoclaves and then pressurising acetic anhydride into it.
Accoya provides the ultimate substrate for our paint coating system and is used in exposed areas such as external beads and external linings on our sash windows. Customers can request that the whole product is manufactured from Accoya if they wish. It also comes with FSC® Chain of Custody.
We manufacture all of our standard door leaves from Red Grandis, a plantation grown timber from Uruguay that comes with FSC® Chain of Custody. It provides a stable and durable substrate and is supplied as a three ply laminated material for extra stability. It is available in long, clear lengths making it highly suitable for stain finishes where no finger joints are preferred.
Red Grandis is a high quality, flawless, uniform timber that lends itself well to a variety of styles and shades and its consistent colour means wood stain can be applied to achieve the desired effect. It is easy to machine and shape and allows for a much sharper cut, all of which saves valuable production time and provides a much better finished – great for us and great for the customer. Customers can also request that the whole product is manufactured from Red Grandis if they wish.
European oak is a very strong, durable Hardwood that benefits from an attractive grain and colour. In the past, high quality timber windows have been made from European Oak due to its durability, however it does have a tendency to move which can cause failure of the coating system and the insulating glass units.
To overcome these problems, we use knot free laminated European Oak which benefits from increased stability and FSC® Chain of Custody. European Oak tends to be used when customers are restricted by planning regulations or if the building lends itself well to oak windows.
European Oak is a very expensive material and the same effect can be achieved by using Red Grandis with an oak stain, which is a much more cost effective way of achieving the aesthetic of oak windows.