This course provides practical guidance on drying timber building components and timber floor systems affected by water damage. Timber in Australian buildings — structural framing, subfloor timbers, suspended timber floors, and solid and engineered hardwood floor coverings — responds to moisture in specific ways that require targeted drying approaches. This course equips technicians to assess timber moisture conditions, select appropriate drying methods, manage the drying process, and determine when timber is restorable versus when replacement is required.
TIMBER AND MOISTURE — KEY PRINCIPLES
Timber is a hygroscopic material — it constantly exchanges moisture with the surrounding air until it reaches equilibrium moisture content (EMC) for the specific temperature and relative humidity conditions. When timber is exposed to water from a damage event, it absorbs moisture rapidly in the direction of the grain (longitudinally) and more slowly across the grain (radially and tangentially). This differential absorption causes timber to swell unevenly, generating internal stress that produces warping, cupping, and in severe cases, splitting.
The practical implication for restoration technicians is that timber that has been significantly wet must be dried slowly enough that moisture can move through the timber at a rate that does not generate damaging internal stress. Very rapid surface drying — from high-velocity air movement, excessive heat, or low humidity — dries the surface faster than moisture can move from the interior, creating surface tension that causes checking (surface cracks) and splitting.
TARGET MOISTURE CONTENT FOR TIMBER IN AUSTRALIAN INTERIORS
The appropriate final moisture content for structural timber varies by climate zone. The Australian Timber Flooring Association (ATFA) specifies equilibrium moisture content ranges for timber flooring by climate zone — approximately 9 to 14 per cent for temperate zones, 12 to 16 per cent for humid tropical zones. Use unaffected timber in the same building as the reference for dry standard determination.
STRUCTURAL TIMBER FRAMING — DRYING APPROACH
Wet structural timber framing (wall studs, top plates, bottom plates, rafters) must be exposed to airflow by removing adjacent lining materials. Plasterboard retained over wet framing significantly slows drying and creates conditions for mould growth in the wall cavity. Open the wall cavity by flood cutting or removing plasterboard sections as required.
Once exposed, direct high-velocity airflow across all timber surfaces. Monitor daily with a pin meter.
Use long pins on the timber meter to measure moisture at depth within the framing, not just at the surface — surface readings may appear dry while the timber core remains elevated. Structural timber framing is generally restorable if dried promptly and if there are no signs of significant mould growth or decay.
SUSPENDED TIMBER FLOORS — DRYING APPROACH
Subfloor timbers in a suspended floor affected by water entry from above or from groundwater must be accessed from below for effective drying. Crawl space access allows deployment of air movers in the subfloor void, directing airflow across the underside of the floor deck and the tops of joists. Deploy dehumidification to manage the humidity in the subfloor void — without dehumidification, the subfloor void can maintain high humidity indefinitely, slowing timber drying.
TIMBER FLOOR COVERINGS — RESTORABILITY ASSESSMENT
Solid hardwood timber flooring that has been wetted requires careful restorability assessment. The degree of cupping (edges raised relative to centre) indicates the extent of moisture differential within the floor assembly.
Mild cupping in a floor affected by a recent clean water event may resolve with controlled drying. Severe cupping, buckling, lifting at joints, and adhesive failure indicate that replacement is more appropriate than continued drying investment.
Engineered timber flooring — a veneer of solid timber over a plywood or HDF core — is generally less restorable than solid timber. The adhesive bond between the veneer and core is vulnerable to moisture, and the composite core materials typically do not return to original dimensions after significant saturation.
