Woodform Architectural examines the advantages and disadvantages of using protective coatings on timber facades in comparison with choosing a naturally weathered finish.

Most architects and their clients prefer to retain the rich sheen on their timber facades, with the lustrous patina showcasing the timber in all its natural splendour. Protective treatments such as transparent oils are used to prolong the original finish of timber facades.

However, all species of timber, if left untreated, will naturally weather after a few years. Exposure to sunlight and moisture triggers an oxidation process that forms a thin silvery film over the timber surface, causing it to lose its original colouration. The resulting silver-grey hue is increasingly considered architecturally attractive for its rustic charm and fundamental expression of timber history.

Advantages of prolonging an original finish

The fresh look of newly-installed timber remains the most preferred timber aesthetic for facades. Application of protective coatings helps achieve a consistent and even finish while still revealing timber tone and grain. Use of a proper exterior finish will inhibit changes in moisture levels, thereby reducing the amount of timber movement and retaining the original aesthetic.

Disadvantages of prolonging an original finish

Periodic aftercare, sometimes at six-monthly intervals, is a necessity for preserving the original colour and sheen of timber. However, weathering cannot be entirely prevented by applying a protective coating over timber, making it difficult to replicate the original colouring. Long-term maintenance can be costly when compared to the naturally weathered timber facade option.

Advantages of natural weathering

Leaving timber to naturally weather into a silver-grey appearance is a recent trend preferred by architects and designers for its organic look that is more in harmony with the surrounding environment. The end-user also saves on significant maintenance costs because there is no pressure to perpetuate the original timber appearance using protective coatings, making the timber-aging option really cost-effective.

Disadvantages of natural weathering

Natural weathering of timber has its disadvantages too: Facade areas that do not receive as much sunlight as other areas, do not weather at the same pace resulting in inconsistent and sometimes, unsightly timber colouration. Lack of protective coatings can also cause moisture to penetrate timber fibres, leading to black spots during the weathering process, although these blemishes will eventually fade with time into a uniform silver-grey. While weathering primarily affects timber appearance, the facade may face long-term durability issues without proactive treatment against possible decay.