News

Sealing Treated Timber

Tarmac SA. Recommended after treatment principles and processes.

Many timber products are preservative treated to extend their service life, ensuring that timber can be used with confidence in many applications ranging from landscaping and fencing to window frames and cladding as well as house framing. The different situations where these products are used involve different levels of weather exposure, fungal decay and insect attack. For example, house framing may be exposed to potential termite attack whereas landscaping timbers may be exposed to fungal decay and termite and borer attack. Modern preservative treatment methodologies use different preservative formulations to give the treated timber product an extended service life. That is why it is important to ensure that the preservative treated timber you buy is treated to the appropriate “Hazard Class” or “H” level for your application. This should be indicated on the timber by a burn brand, label or mark indicating the appropriate H-level, For example, treated timber for outdoor use in above ground applications should be treated to an H3 level. Treated timber for ground contact applications should be treated to an H4 level or H5 depending on ground conditions.

All preservative treatments complying to the Australian Standard (AS1604 series) are treated in dedicated timber treatment facilities. Most traditional timber treatments are applied using a vacuum/pressure process. However, new generation treatments can be applied by a dip or spray or in the glue matrix of engineered timber products such as plywoods, LVL and others. When a treated timber product is cut, notched, drilled or worked in any way that breaks the surface of the timber product, then it is generally recommended that a resealing preservative product be applied to the exposed areas. Resealing with a preservative is important to protect untreated coated areas from fungal decay or insect attack.

Different Product Categories and Formulations Need Different Sealant Strategies
Water based Copper Preservative Treatments
Includes MicroPro, (Micronized Copper Quat), CCA (Copper Chrome Arsenate) and ACQ (Alkaline Copper Quaternary)
Products treated with these formulations should be resealed with PROTIM SOLIGNUM CN TIMBER OIL (CN Oil). This is a copper –based solvent/oil formulation that is green in colour. If a paint system is to be applied after resealing, allow time for the CN Oil to be absorbed into the timber and then follow paint manufacturers recommendations. 
Solvent Preservative Treatments
Products treated with these formulations should be resealed with PROTIM SOLIGNUM XJ CLEAR TIMBER PROTECTIVE (XJ CLEAR). If a paint system is to be applied after resealing, allow time for the XJ Clear to be absorbed into the timber and then follow paint manufacturers recommendations. 
Envelope Treated “Blue” Interior Timber Framing
These products have a preservative product applied to surface of the timber including the ends. Because the timber is protected by an envelope of preservative on the outside of the timber, it is recommended to reseal any exposed timber as a result of cutting, notching or drilling holes for services. If the cut end is to be butted against a treated surface in service, then resealing is not required. See Osmose “Determite” Information sheet for further advice and product description. Use PROTIM-SOLIGNUM XJ CLEAR TIMBER PROTECTIVE (XJ Clear) for Blue Treated framing.

For application information on Protim Solignum TimberCare products and other important information, visit www.osmose.com.au.