"Wood" - what is it, definition of the term
Timber, a natural composite derived from the secondary xylem of trees and woody plants, consists chiefly of cellulose fibers bound within a lignin matrix, granting it structural rigidity, durability, and anisotropic mechanical properties; it is harvested, processed, and employed across construction, furniture, and energy sectors as a renewable, load‑bearing material.
Detailed information
Timber consists primarily of cellulose fibers, hemicellulose, and lignin, forming a hierarchical structure that provides strength and rigidity. Growth rings create alternating zones of earlywood and latewood, influencing density and moisture movement. Species differ in grain pattern, hardness, and natural durability; common selections include oak, pine, maple, and teak.
Mechanical properties vary with moisture content. At 12 % moisture, typical values are:
- Modulus of elasticity: 10–14 GPa for softwoods, 12–20 GPa for hardwoods.
- Bending strength: 40–80 MPa for softwoods, 70–150 MPa for hardwoods.
- Compression parallel to grain: 30–50 MPa for softwoods, 45–80 MPa for hardwoods.
Processing stages involve felling, debarking, sawing, drying, and finishing. Kiln drying reduces equilibrium moisture to 6–8 %, minimizing dimensional change. Surface treatments—oil, varnish, or pressure‑impregnation—enhance resistance to biological agents.
Rodents such as rats and mice exploit timber in several ways. They gnaw to sharpen incisors, creating entry points for nesting and foraging. Damage manifests as:
- Parallel or irregular chew marks on structural members.
- Accumulation of droppings near compromised areas.
- Burrow tunnels that compromise insulation and load‑bearing capacity.
Preventive measures focus on exclusion and material selection. Strategies include:
- Installing metal or plastic mesh at ventilation openings.
- Using hardwoods with high natural resistance (e.g., teak, ipe) in vulnerable zones.
- Applying rodent‑repellent preservatives during finishing.
- Maintaining low indoor humidity to deter nesting.
Repair of infested timber requires removal of affected sections, sterilization of the surrounding area, and replacement with treated material. Structural assessment should verify that load paths remain intact before reinstating service loads.
Understanding the interaction between forest material and gnawing mammals informs design choices that extend service life and safeguard structural integrity.