Content supplied by George Barnsdale
So is it true that timber windows require regular maintenance to maintain their beauty and performance? Well it would be foolhardy for me to simply answer ‘no’ because so many factors affect the durability of a window – the type of timber used, how the timber is treated, the design, the coating and how the coating is applied. However, timber windows have significantly evolved over the past decade and you may be surprised to know that an independent study by Heriot Watt University found that the Planned Service Life of a timber window frame manufactured to standards set by the Wood Window Alliance is between 56-65 years, depending on climate exposure.
But what should you be looking for when choosing timber windows to ensure longevity and performance? To help you with this, here is a checklist of key considerations that need to be taken in account when you come to specify:
The type of timber
A paint or stain coating will only perform to a high standard if applied to a suitable timber species. The types of timber that have been proven to perform to a high standard are:
- Engineered Redwood – Laminated and free of knots and imperfections, Engineered Redwood not only enhances the beauty of a timber window, but increases stability and eliminates knot bleeding. It is an excellent timber species for products requiring a paint finish because the reduced moisture uptake and increased stability produces a substrate which enhances the coating’s life span.
- Grandis Hardwood – Supplied as a three ply laminated timber for extra stability, Grandis Hardwood is extremely durable and is best suited for those stain coatings because of its clear-faced attractive grain pattern.
- Accoya® – This timber species has earned the highest durability rating of any timber and is especially recommended for coastal areas.
- Laminated European Oak – Be cautious in the specification of European Oak as it has a tendency to move which can cause failure of the coating system and glazing units. To overcome these problems, some manufacturers use knot free laminated European Oak which provides a greater amount of stability.
How the coating is applied
The type of coating and how it is applied significantly contributes to the longevity of any timber window. Any coating must provide maximum protection to the timber while allowing it to breathe and let its natural beauty to show through. Some manufacturers of factory finished timber windows have developed a controlled factory environment for the application of coatings which greatly enhances performance and longevity.
The coating – paint or stain?
Factory finished timber windows tend to have a micro-porous stain or paint coating. A micro-porous coating allows the timber to breathe which helps to reduce flaking and cracking issues. It is accepted that paint coatings will last longer than stains, and manufacturers will reflect this in their guarantees. Fully finished factory windows actually require very little maintenance. Depending on the severity of climate exposure, a factory finished timber window with a paint coating will not need recoating for eight or more years. Many manufacturers’ provide instructions on recoating and preventative steps that can be taken to extend a coating’s life expectancy.
The window design
As with any industry, advances in technology have helped the timber window industry progress window design to enhance life expectancy and performance. Consideration needs to be given to how the window is glazed and the types of seals incorporated into the design.
The robustness of guarantees
The final point to make is to explore the guarantees that are offered by the manufacturer. Many will offer standard guarantees but the actual guarantees given will depend upon the type of product, the type of coating and the climate. It’s advisable to check what is and isn’t covered before you make your final decision. A good starting point is a company’s guarantee brochure.