Glossary
Acrylate Resin produced through polymerisation of esters or salts of acrylic acid or methacrylic acid or a mix of these acids’ esters. Sometimes called polyacrylate. See Surface treatment of exterior wood and Surface treatment of interior wood.
Acrylic paint Latex paint with acrylate resin as the main binder. Only occurs as water-based paint. See Surface treatment of exterior wood and Surface treatment of interior wood.
Alkyd Resin made via polymerisation of diolic or polyolic carbonic acids with polyolic alcohols. Condensation is usually used with fatty acids or glycerides of these. See Surface treatment of exterior wood and Surface treatment of interior wood.
Alkyd paint Paint with alkyd resin as the main binder. Occurs as both solvent-based paint and water-based paint. See Surface treatment of exterior wood and Surface treatment of interior wood.
Anisotropic Wood is an anisotropic material, which means that its properties are different in different directions. This applies, for example, to the effects of moisture and of loads. See Strength.
Beams Sawn timber, main yield, that is used in buildings for example as floor joists or structural elements in wall and roof structures. The difference between thickness and width is usually greater than 25 mm. See Strength, Structural elements, Wood in the construction process, Wood in civil engineering and Structural fixings.
Bark-encased scar Ingrown bark in the wood, usually when healing over trunk damage, a cleft or a spike knot. May be found in bark-encased knots or bark-encased open splits. See Wood grades.
Binder The film-forming constituent of paints used to achieve adhesion to the substrate and bind together the other constituent substances in the paint. Organic binders include synthetic polymers, oil or alkyd. See Surface treatment of exterior wood and Surface treatment of interior wood.
Bioenergy (bark) Bioenergy covers all use of biomass as an energy source. The material is usually converted into pellets for use in cogeneration plants to produce electricity and thermal energy. See Wood is a sustainable construction material and From log to plank.
Firewood Tree trunks, branches and roots that are used directly as fuel. See The forest and sustainable forestry and From log to plank.
Bending strength Material technology term for the maximum tension a material can absorb in a bending test. See Properties of coniferous wood, Strength, Strength grading and Structural elements.
Reference value The agreed measurement of width, thickness and length that applies to the timber, and the allowable dimension deviations for thickness and width in two different tolerance classes (usually equating to planed and sawn timber). See Cross-sectional dimensions.
c 1200 c denotes the internal centre spacing of e.g. 600 or 1200 millimetres. See Structural elements and Choosing the right screw when building with wood.
CE Conformité Européenne (European Conformity). CE is a product label confirming that the product complies with basic requirements in areas such as health, safety, performance and the environment, and that prescribed control procedures have been followed. See Strength grading, Wood for construction purposes, Structural elements and Building regulations.
CEN European Committee for Standardization, Comité Européen de Normalisation, draws up EU standards. See Building with wood is positive for the climate.
Main yield Sawn timber that is taken from the centre part of the log. Main yield with a thickness above 32 mm is often called a plank. See From log to plank, Wood for construction purposes and Wood for the joinery industry.
Density Ratio of a material’s mass to volume; unit kg/m3. See Properties of coniferous wood – Strength, Wood and moisture, Wood protection and Strength grading.
Vapour tight A material that is vapour tight prevents water molecules from moving from an area with high vapour content to one with low vapour content. See Wood in the construction process.
Dimension planed timber Wood that has been planed on four sides to achieve a particular cross-sectional dimension. Has a lower quality appearance than smooth planed wood. Used primarily for encasing. See Wood grades .
Dimensional stabilisation Wood can be stabilised chemically or physically to prevent or limit movements in the wood. See Wood protection.
Dispersed Acrylic paint, which comprises polymer materials, is finely dispersed in water in what is known as a dispersion – a liquid containing tiny suspended particles. See Surface treatment of exterior wood.
Dispersion paint Paint whose binder takes the form of a dispersion. The binder might be acrylate dispersed in water, for example. See Surface treatment of exterior wood.
Tensile strength Measure of a material’s capacity to withstand pulling forces; measured in a pull test. See Properties of coniferous wood and Strength.
V-jointed tongue and groove Tongue and groove wood with a chamfered edge on one face next to both tongue and groove.
Dowel Dowels are used to make hidden joints. Wooden dowels were used historically, today steel dowels are employed in large wooden structures. See Structural elements.
EN European standard from CEN. See Building with wood is positive for the climate.
ENV European pre-standard from CEN. See Measuring average moisture content and surface moisture content.
EPD Environmental Product Declaration (EPD) is an information system for factually describing the environmental properties of products and services from a life cycle perspective. Initiated and run by the business world, Miljöstyrningsrådet is the body that administers the EPD system in Sweden. See Building with wood is positive for the climate.
Modulus of elasticity Describes the correlation between load and stretching/bending in a material. See Properties of coniferous wood, Strength and Strength grading.
Half V-jointed tongue and groove Tongue and groove wood with chamfer on one face next to the tongue only.
Extractive substances These are substances such as fatty acids, resin acids, stearyl esters and glycerides that occur in the heartwood of pine. See Properties of coniferous wood.
FSC Forest Stewardship Council (FSC) is a certification system confirming that wood comes from forests that are responsibly managed from an environmental, social and economic perspective. See The forest and sustainable forestry and Wood protection.
Fibre saturation point The point above which wood contains both free and bound water but below which it only contains bound water. See Moisture content, Measuring average moisture content and surface moisture content, Moisture-related wood movement and Microorganisms.
Finger joint Glued joint for joining lengths of wood, comprising finger-like wedges. Finger jointing is performed industrially under controlled conditions, using different adhesives depending on the intended application. See Strength grading, Cross-sectional dimensions, Wood and wood-based products, Wood for construction purposes and Structural elements.
Fine sawn Wood that is sawn after drying. At least one face is sawn with a band or circular saw. See Surface structures, Wood for construction purposes and Surface treatment of exterior wood.
Tongue The protruding section along the edge of tongue and groove boards that fits into the groove.
Photosynthesis Photosynthesis is the process whereby living organisms take energy from light and store it in chemical compounds. Photosynthesis creates energy-rich oxygen and carbohydrate molecules from carbon (CO2) and water (H2O). See The forest and sustainable forestry and Wood is a sustainable construction material.
Moisture content The ratio of the mass of water in damp material and the mass of the dried material, expressed in percent, %. See From log to plank, Properties of coniferous wood, Strength, Wood protection, Cross-sectional dimensions, Microorganisms, Wood for construction purposes, Wood in the construction process, Handling and storage and Surface treatment of exterior wood.
Moisture gradient Variation in moisture content in the cross-section of the wood. See Moisture content and Measuring average moisture content and surface moisture content.
Paint Material comprising binder, binder solvent or binder emulsion and colourants in the form of dispersed pigments, intended to be painted onto a surface and form a thin film after drying. See Wood protection, Surface treatment of exterior wood, Surface treatment of interior wood and Choosing the right screw when building with wood.
Glucose Glucose is one of the most important carbohydrates, used as an energy source by plants and animals. Glucose is also a building block of the polysaccharides starch, cellulose and glycogen. It is one of the building blocks of growing trees. See Wood is a sustainable construction material.
Thread The three-dimensional spiral pattern that runs along a screw, for example. When fixing wood, screws with different types of threads are used to suit the different types of materials being fixed together. There are also reverse threaded screws to fix two pieces of wood together more firmly. See Nails and screws and Choosing the right screw when building with wood.
Resin Another name for pitch, this is the collective term for a number of semi-solid or hard organic substances, both natural and artificial. See Properties of coniferous wood, Moisture content, Structural elements and Surface treatment of exterior wood.
Head The part of a nail or screw against which it is hammered or screwed in. See Nails and screws and Choosing the right screw when building with wood.
Hybrid paint Water-based paint whose binder is a combination of alkyd and acrylate. See Surface treatment of exterior wood.
Hygroscopy The capacity to absorb and release water vapour. See Durability and resistance.
Planed timber Wood planed on all sides. See Properties of coniferous wood, Wood protection, Wood grades, Cross-sectional dimensions, Sawn timber range, Common wood profiles, Wood for construction purposes and Surface treatment of exterior wood.
Hardness Hardness is a material property describing what forces are needed to cause plastic deformation in the material. Hardness is not the same as density and is measured in the units Brinell or Janka. See Properties of coniferous wood, Strength, Measuring average moisture content and surface moisture content and Wood protection.
Impregnation Industrial pressure treatment of wood whereby preservative is forced into the sapwood. See From log to plank, Wood protection and Wood in the construction process.
ISO The International Organization for Standardization (ISO) draws up global standards in a number of different areas. See Building with wood is positive for the climate.
Equilibrium moisture content Wood in air at a constant temperature and constant humidity gradually adopts a particular moisture content, the equilibrium moisture content. See Moisture content and Moisture-related wood movement.
Casein A milk protein that is used as a binder in adhesive. See Surface treatment of exterior wood.
Resawing Separating wood along the edge. See Wood grades, Wood for construction purposes, Wood for the joinery industry and Structural elements.
Carbon dioxide Carbon dioxide (CO2) is released by all aerobic organisms (plants, animals, fungi and many microorganisms) as part of their respiration. In the human body, carbon dioxide is a waste product that forms during cellular respiration and leaves the body in exhaled air. With the help of photosynthesis, plants convert carbon dioxide and water into sugars, which they use in their own metabolism or store in their cells, usually converted into cellulose, starch or fat. See The forest and sustainable forestry, Wood is a sustainable construction material and Building with wood is positive for the climate.
Carbohydrates Carbohydrates is the collective name for starch, fibre and various sugars. Glucose is a type of sugar that helps to build up our trees. See The forest and sustainable forestry and Properties of coniferous wood.
Conditioning Wood is conditioned during the drying process at the sawmill. This evens out drying tensions in the wood to reduce cracks in the wood after drying. See Moisture content, Measuring average moisture content and surface moisture content and Moisture-related wood movement.
Construction timber Wood intended for parts of a building that will have to carry a load. Construction timber is usually made from spruce. Pine is only used if pressure treated construction timber is required, since timber from spruce is difficult to impregnate. See Wood grades, Strength grading, Cross-sectional dimensions, Wood for construction purposes, Structural elements, Handling and storage and Building regulations.
Chalk Chalk is a rock comprising pure calcium carbonate (CaCO3) that is used in various paints. A surface may turn chalky, which means fading compared with the original colour of the paint pigment. See Surface treatment of exterior wood.
Cultured forest Cultured forest is forest that is the result of forestry practices, not natural forest or wild forest. See The forest and sustainable forestry.
Colour, tone, shade The ability of a material to reflect or let through light of a particular wavelength composition. Different wavelength compositions cause visual perceptions that can be described, for example, as red, grey, brown and black. See Surface treatment of exterior wood.
Pitch pocket A pitch pocket is an opening between two growth rings in a piece of wood, usually filled with pitch. See Properties of coniferous wood, Wood grades and Structural elements.
Pitchwood Pine with abnormally high pitch content. Unsuitable for wood that is intended to be touched or varnished. See Wood grades and Wood for construction purposes.
Cavetto A moulding with a semi-circular groove in it is called cavetto.
Heartwood Inner part of the wood in the growing tree, whose cells are dead and no longer transport sap. Usually darker in colour than sapwood, but not always clearly discernible. See Properties of coniferous wood, Durability and resistance, Moisture-related wood movement, Wood protection and Wood for construction purposes and Wood for the joinery industry.
Lamination effect Laminated wood may contain weakening knots or other defects. There is only a very small risk of defects in several laminates occurring in the same section. See Structural elements.
Delivery moisture content The moisture content that the wood is required to have on delivery, according to the order. Usually given as target moisture content. See Moisture-related wood movement.
Lignin The wood’s natural glue, it helps to give wood its mechanical strength. Lignin binds the cellulose fibres together to form a strong wood structure. See
Properties of coniferous wood and Microorganisms.
Glulam Glulam usually comprises 45 mm thick laminates (33 mm in curved sections) of construction timber that are glued together. This makes it possible to manufacture larger glulam components than would be possible just from construction timber. See Building with wood is positive for the climate, From log to plank, Strength, Measuring average moisture content and surface moisture content, Strength grading, Cross-sectional dimensions, Wood for construction purposes, Structural elements, Wood in the construction process, Wood in civil engineering, Handling and storage, Nails and screws and Building regulations.
Moulding Planed or profile planed timber with a small cross-section. See Properties of coniferous wood, Measuring average moisture content and surface moisture content, Wood grades, Cross-sectional dimensions, Surface structures, Wood for construction purposes, Handling and storage, Surface treatment of exterior wood, Surface treatment of interior wood and Choosing the right screw when building with wood.
Open split Stem damage on the bark or cambium of a growing tree can cause an open split to form as the damage is enclosed by later growth rings. The open split may contain both bark remains and pitch deposits. See Wood grades.
Batten (lath) Split timber in thicknesses of 12–38 mm and widths of 25–63 mm. See Wood protection, Cross-sectional dimensions, Structural elements, Handling and storage, Surface treatment of exterior wood, Nails and screws, and Choosing the right screw when building with wood.
m Abbreviation of metre.
mm Abbreviation of millimetre.
m3 Abbreviation of cubic metre.
mn Abbreviation of millions.
bn Abbreviation of billions.
Average moisture content Allowable variation in average moisture content for wood batch. See Moisture content and Handling and storage.
µm Micrometer, 0.000001 metres or one thousandth of a millimetre. See Measuring average moisture content and surface moisture content, Surface treatment of exterior wood, Nails and screws and Choosing the right screw when building with wood.
Target moisture content Requested moisture content in a batch of wood, expressed as a percentage, see SS-EN 14298. See From log to plank, Moisture content, Measuring average moisture content and surface moisture content, Moisture-related wood movement, Microorganisms, Wood protection, Wood for construction purposes, Wood in the construction process and Handling and storage.
Pith Area within the first growth ring, mainly comprising soft tissue. The pith is a dark brown colour. See From log to plank, Properties of coniferous wood, Wood for construction purposes and Wood for the joinery industry.
Pith catcher This is the process of sawing a log so that the pith is contained in a single piece of wood and can be removed, giving pith-free wood in all the remaining pieces from the log for the joinery industry. See From log to plank and Wood for the joinery industry.
Natural forest Natural forest is forest that has remained unaffected by human activity for so long that most of it has regained the characteristics of wild forest. A distinction is drawn between primary natural forest that has always been forest, even though it has been subject to human influence, and secondary natural forest that for some time was open farmland or some other type of open land and then regenerated when the land was left unfarmed. Planted forest is never counted as natural forest and natural forest never counts as wild forest. Around 3% of Sweden’s total forested land is natural forest. See The forest and sustainable forestry.
Groove Lengthwise indentation (track) in one edge of tongue and groove wood designed to fit a tongue and make a joint.
PCR Product Category Rules (PCR) constitute a framework for the EPDs. SS-EN 15804 is one such framework standard for EPDs. Following this general basis, each material category then draws up its specific EPDs. Within the wood sector, a PCR proposal has been put together for wood and wood-based products. See Building with wood is positive for the climate.
PEFC The Programme for the Endorsement of Forest Certification schemes (PEFC) is a certification system confirming that wood comes from forests that are responsibly managed from an environmental, social and economic perspective. See The forest and sustainable forestry and Wood protection.
Penetrating oil An oil that penetrates into the wood. See Moisture content, Wood protection and Surface treatment of exterior wood.
Pigment The substances in paint that give it its colour, generally very finely powdered inorganic substances. See Surface treatment of exterior wood.
Smooth planed timber Wood with four planed sides. Has a higher quality appearance than dimension planed timber and is used mainly for exposed surfaces indoors. See Wood grades, Surface structures and Wood for construction purposes.
Sawing pattern The geometric pattern that will be used to saw up the log. See Moisture content.
Profile planed timber Planed timber with a special cross-section.
Pin knot A small, generally dark, dry knot with a diameter of max. 7 mm that occurs in spruce. See Properties of coniferous wood and Wood grades.
Beaded tongue and groove Cladding with a bead running down one face, next to the tongue.
ROT ROT is a Swedish abbreviation for repair, refurbishment and extension work on existing buildings. See From log to plank.
Joists Sawn or dimension planed timber in thicknesses of 34–50 mm and widths of 70–150 mm. See Measuring average moisture content and surface moisture content, Wood protection, Cross-sectional dimensions, Wood for construction purposes, Structural elements, Wood in the construction process and Nails and screws.
Relative humidity Also called relative vapour concentration. This is the ratio between actual vapour concentration and saturation vapour concentration, expressed in percent. See Moisture content, Moisture-related wood movement and Microorganisms.
Grooving Grooving is a basic profiling of a planed surface to give paint better adhesion. See Surface structures, Wood for construction purposes and Structural elements.
Rib head Screw head with ribs underneath to countersink the screw into the wood during fixing. See Nails and screws, Choosing the right screw when building with wood.
Part planed timber Timber with a rectangular cross-section, one sawn face (good side) and other sides planed or grooved. See Cross-sectional dimensions.
SIS Swedish Standards Institute (SIS), Swedish member of ISO and CEN. See Building with wood is positive for the climate.
SS-EN An EU standard that has been introduced as a national Swedish standard is called SS-EN. See Building with wood is positive for the climate.
Siccative A siccative is a type of drying agent for linseed oil paints, which catalyses drying reactions in the oily binders by speeding up the oxidation and/or polymerisation of the linseed oil. See Surface treatment of exterior wood.
Sideboards Sawn timber taken from the outer part of the log, outside the main yield, also known as side yield. Sideboards have a thickness of less than 32 mm. See From log to plank and Wood for the joinery industry.
Shipping mark When adjusting boards and planks at the sawmill, the end of the wood is stamped with a shipping mark. This states the wood grade and the manufacturing sawmill. See Wood grades.
Shear strength Shearing is a deformation without volume change. It is defined as an angle change created by the deformation. Shearing arises from two shear forces working in parallel with the cut surface. See Properties of coniferous wood and Strength.
Forest volume Forest is measured in cubic metres, m3. Forest cubic metres (m3 sk) is the volume of the stems including bark, but without branches and stump. A 26 metre tall spruce with a diameter at breast height of 32 cm is approximately 1 m3 sk. See The forest and sustainable forestry and From log to plank.
Impact strength A material or structure’s capacity to resist blows and knocks, i.e. short-lived loads, without breaks occurring. See Properties of coniferous wood.
Planed tongue and groove Tongue and groove wood planed on all sides. See Wood for construction purposes.
Cross grain When the fibre direction of the wood is not parallel with the longitudinal axis of the stem. See Properties of coniferous wood, Wood grades, Strength grading and Structural elements.
Spar Sawn timber with a thickness of at least 75 mm. There is usually no or max. 25 mm difference between the thickness and width. See Cross-sectional dimensions.
Point The pointed tip of a nail or screw. See Nails and screws.
Sapwood Outer part of the wood in the growing tree, which contains cells that transport sap. Usually lighter in colour than heartwood, but not always clearly discernible. See Properties of coniferous wood, Durability and resistance, Moisture content, Moisture-related wood movement, Microorganisms and Wood protection.
Tongue and groove wood Wood with a tongue on one edge and a groove on the other to form a tongue and groove joint. See Wood grades, Wood for construction purposes, Structural elements, Wood in civil engineering, Handling and storage, and Surface treatment of exterior wood.
Splitting Sawing through the face of the wood. See Wood for the joinery industry.
Grooves Wood surfaces may carry different grooved marks from the sawing process. See Surface structures .
Profiled boards can together form grooves between them. See Structural elements.
Profiled boards may have grooves on the reverse to limit dimensional changes.
Grooves in a screw head help to drive the screw in. See Nails and screws.
Butt joint When two pieces of wood are joined end to end. See Structural elements.
Substitution In environmental work, substitution means trying to replace substances and production methods with those that are less harmful to the environment. See Wood is a sustainable construction material and Building with wood is positive for the climate.
Sawn timber Wood with four sawn sides. See Building with wood is positive for the climate, Moisture content, Measuring average moisture content and surface moisture content, Moisture-related wood movement, Wood grades, Cross-sectional dimensions, Surface structures, Common wood profiles, Microorganisms, Wood for construction purposes, Wood for the joinery industry, Structural elements, and Handling and storage, Surface treatment of exterior wood.
Imperfection An imperfection can occur in a piece of wood or a particular type of wood component. See Properties of coniferous wood and Structural elements.
T-virke Construction timber sorted and labelled according to Swedish standard SS 230120. See Strength grading and Cross-sectional dimensions.
Compression wood This is a deviating property or grade of coniferous wood. Compression wood has thick-walled cells and the wood in these growth rings is darker than the normal wood. It is formed mainly on the underside of leaning trees, which try to return to a vertical position as they grow, and in branches. Compression wood forms due to prolonged pressure. See Wood grades and Strength grading.
Top rupture When the top of a tree is damaged, this causes a top rupture that affects the fibres in the structure of the tree and gives negative properties when assessing the grade. See Wood grades and Strength grading.
Dry content Dry content is the amount of dry substance in a solution. The dry substance is the amount of dry material that remains after complete drying of a paint. See Surface treatment of exterior wood.
Compression strength A capacity to tolerate certain compression forces. See Properties of coniferous wood and Strength.
Cross-sectional dimensions Width and thickness/height of a piece of wood or a beam. See From log to plank, Wood protection, Cross-sectional dimensions and Surface structures.
Visible width The part of a tongue and groove or rebated board that remains visible after installation.
Sheathing Tongue and groove wood with one grooved face and the other planed or grooved, and the other sides planed. See Wood grades and Structural elements.
Wane The log’s original skin, with or without bark, on a corner of sawn timber. See From log to plank, Wood grades and Strength grading.
Wet wood Damage to the heartwood of older pines due to water penetrating through dead knots. When the water freezes, this causes splits in the heartwood. See Wood grades.
Viscosity A physical attribute of liquids and gases that indicates their “thickness” or internal resistance to flow, and can be seen as a measure of friction in fluids. “Thin” fluids such as methanol have low viscosity, while “thicker” ones such as oil have high viscosity. See Surface treatment of exterior wood.
Raised grain Also called compression wood. Raised grain is a deviating property or grade of coniferous wood. Raised grain wood has thick-walled cells and the wood in these growth rings is darker than the normal wood. It is formed mainly on the underside of leaning trees, which try to return to a vertical position as they grow, and in branches. Raised grain wood forms due to prolonged pressure. See Wood grades.
Thermal capacity (specific heat) This is the amount of heat in Ws or kJ that is needed to heat 1 kg of the material by 1°C.
See Properties of coniferous wood and Strength.
Thermal conductivity (λD value) States the number of W that are conducted per time unit through 1 m2 of a 1 m thick material when the temperature difference between the material’s sides is 1°C. See Properties of coniferous wood and Strength.
Calorific value States the amount of heat that is generated from complete combustion of the material. See Properties of coniferous wood and Strength.
Surface moisture content Measured on the surface of a piece of wood, should be 16% or lower for painting and 18% or lower if being encased. See Moisture content, Measuring average moisture content and surface moisture content, Microorganisms, Wood protection, Wood in the construction process, Handling and storage and Surface treatment of exterior wood.
Vapour concentration The ratio between the mass of the vapour and the total volume of the gas mix (air), expressed in kg/m3. See Moisture content.
Four-sided tongue and groove Wood with two tongued edges and two grooved edges.
Open assembly time The time that the wooden structure is open to the wind and weather during assembly or construction on site. See Wood in the construction process.
Trimming allowance The remains of overcompensation for shrinkage between sawing of the raw log and the dimension on delivery. See From log to plank.