Frequently Asked Questions

Treating Glulam Timbers with Waterborne Preservatives

Can structural glued laminated timber (glulam) be treated with waterborne preservatives after laminating?

In general, the laminated timber industry recommends against using waterborne preservative chemicals to pressure-treat structural glued laminated timbers after bonding. This recommendation is intended to prevent appearance problems caused by the treatment and subsequent re-drying (AITC 109-2007). However, pressure-treatment with waterborne chemicals after bonding does not generally make the laminated timber structurally unfit. Treating structural glued laminated timber (glulam) with waterborne chemicals after bonding may be a viable option for applications where appearance is less critical.

While not generally recommended due to aesthetic issues, the pressure-treatment of structural glued laminated timbers with waterborne preservatives after bonding may be a viable option for many uses where appearance is less critical. Adhesives used in modern glulam are extremely durable and are considered waterproof. Glulam timbers treated after bonding will accept treatment and resist decay similar to treated sawn timbers of the same species and will perform similarly in service. If the appearance of this product is acceptable to the consumer, it can be used successfully in applications where treated wood is required.

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