A-Z Wood Flooring


The procedure of placing wood flooring in the area where it is to be installed to enable it to ‘acclimatise’ or adjust its moisture content to correspond with that of its surroundings.

Ted Todd recommends that all floors are acclimatised within their packs for 2 to 3 days in the room to be installed to allow the temperature of the floor to equalize with its environment ensuring job site conditions are met.

Ensure that the building is enclosed.

Verify that the building is maintained at normal living conditions for temperature and humidity.

Where building codes allow, permanent heating and/or air-conditioning systems should be operating at least five days preceding installation to promote proper acclimatisation.

If it is not possible for the permanent heating and/or air-conditioning system to be operating before, during and after installation, a temporary heating and/or dehumidification system that will mimic normal temperature and humidity conditions can enable the installation to proceed until the permanent heating and/or air-conditioning system is operating.

Packs should be stacked flat on the floor or on battens (not upright) allowing for airflow around the stacks

If the delivery is for more than one room the order should be broken down into the individual room quantities and stored in the respective rooms.


Paste used for fixing flooring to its subfloor. Usually spread with a notched trowel – it is important to use a trowel with the correct sized notches so as to apply the correct quantity of adhesive. The best adhesives will be flexible allowing the wood floor to move with the natural variations in humidity. Ted Todd MS Flex is the best adhesive for this purpose.

Adhesives, usually of the PVA type, are also used for gluing together the T&G of the floorboards in a floating installation.


Aged floors are those that which are manufactured from new, sawn French oak boards that have been allowed to season for up to 24 months. Skilled artisans then apply their craft to produce plank, chevron or herringbone floors emphasising the grain and undulating textures of the oak.

Air Dry

A method of drying timber by atmospheric conditions between its natural state as a tree and its use in building. Air-dried timber is not usually sufficiently dry for hardwood flooring and kiln drying is required to achieve a moisture content of 8 to 10%, which conforms to BS8201.


A term applied to floors and panels manufactured from restored woods with history embedded to their core. Restored and rejuvenated, piece by piece, by expert craftsmen into specially commissioned classic floorboards or more intricate parquetry and panels.


An implement for applying adhesive, oil, seal or other dressing.

Architectural Elements

A term used to describe specially designed, functional structural and decorative profiles such as skirtings and architraves.


A wooden frame for doorways. Usually requires undercutting to permit wood flooring to fit under it.


A piece (usually) of softwood which supports the hardwood flooring and to which it is often fixed by nailing.


A decorative feature whereby the sharp edge of the board is planed off. The bevel more clearly defines the board’s edge and this can add to the beauty of the floor. Sometimes also called an ‘eased’ edge. There is no industry standard for bevel size, so it varies from producer to producer – however, it is usually angled at 45 degrees and between 0.5mm and 2mm deep. See also Hand-Rolled Edges and Broken Edge.

Bird’s Eye

A distinctive figure in Maple which is said to look like a bird’s eye.

Black Oxidised

Wood that has turned black through the oxidation process. The wood may be naturally blackened over time or new wood may be turned black through an artificial blackening oxidation process.


The process by which a chemical is applied to timber in order to lighten it. Certain hardwoods are bleached by sunlight –e.g. Walnut, Cherry and Oak.

Brown Oak

A distinctive type of Oak that is a deep, chocolate colour. English Brown Oak is actually white Oak that has turned brown due to a fungal infection (beef steak fungi) that causes a chemical change in the tree. It is a rich honey brown colour.

Blocks or Parquet Wood Blocks

Pieces of flooring timber, varying in size, but usually in the region of 200-275mm x 65-75mm x 20mm. Most blocks are tongued and grooved (see below) and adhered to a screeded subfloor with adhesive. Can be laid in different patterns; basket weave, herringbone, half bond etc.

Blocks (or Planks or Strips)

A form of wood flooring composed of elements from 60-200mm wide (sometimes smaller or larger) and from 500mm to 2500mm in length, often random lengths. Boards can be secret nailed (see below) or glued. Solid boards must never be fixed by the ‘floating floor’ method.


A feature in a floor, whereby a contrasting timber is inset around the perimeter. Sometimes called an ‘inset strip’.

Brinell Scale of Hardness

A scale that compares the hardness of various species of timber. On the Brinell scale, Oak has a value of 5 whereas Jatoba has a value of 7 indicating Jatoba is harder than Oak. See also Janka Hardness rating.

Broken edges

A reference to the edge detail on floorboards and the visual effect it has when the boards are put together. Broken edges are normally applied by either machine or hand to remove the sharpness from square-cut pieces.


Burnishing is the process applied to wood floors during and after the application of oils.

Often done by hand, it involves rapidly rubbing the surface of the floor with various mediums which has the effect of melting the oils and waxes and blends these in with the wood fibres making a very smooth, luxurious, hardwearing finish.


The painstakingly intricate process involved that pays homage to the ancient Japanese process of Shou Sugi Ban. Boards used to manufacture these floors and panels are individually charred by flame in carefully controlled conditions to enable this unique surface effect.

Care and Maintenance

The essential part of wood floor ownership to ensure that the end user applies the correct methods and materials needed to allow their floor to withstand decades of future use.

Care System

Usually given a number, 1 or 2, depending upon the wood floor finish type to be looked after.

A good Care System will include all of the materials and detail the process for looking after a wood floor. The use of the correct Care System will be necessary to validate any warranty or guarantee.

Case Hardened

Case hardened is used to describe timber that has been improperly dried. If dried too quickly, wood shrinks heavily on the surface compressing its still damp interior. This results in unrelieved case-hardened wood which may warp considerably and potentially dangerously when the stress is relieved by sawing. This is a commonly known term, but case-hardened timber is not as common as people think.


The carbohydrate that is the principle constituent of wood. It forms the frame work of wood cells.


A lengthwise separation of the wood which extends across the rings of annual growth, usually resulting from stress, set up in wood during seasoning.


A design of floor block in a parallelogram shape, usually with a 60-degree or 45-degree angle.Normally laid in a V pattern.


A board made from particles of wood, mechanically compressed with glue or other binders to produce a board. Chipboard is a very common subfloor material today, particularly in new construction. It should be avoided in damp conditions although you can source flooring grade chipboard that is damp-proof. Serrated nails are recommended when fixing, as chipboard does not retain standard nails well. Resin-bonded ply is an alternative.


The Convention on International Trade in Endangered Species of Wild Fauna and Flora is an international agreement aimed at regulating the trade in wild life. Species can be listed on one of three appendices to the treaty which impose levels of restriction on international trade. Although there have been attempts by environmentalists and some governments to list a range of over-exploited timber species on CITES, there are currently just 46 CITES-listed trees by Species or Genus listed under this agreement, of which only a few are major timbers. Producer countries frequently oppose moves to list species to protect their logging interests, although some appreciate the help it can provide in controlling trade in over-exploited species.

Click Joint

A method of joining the boards of floating floors together without using glue. The tongue is made with a protrusion that fits over a corresponding rebate in the groove, so called because the elements often “click” when pushed together. Not recommend for use with solid boards as the precise jointing mechanism is susceptible to slight changes in moisture – rendering the system useless.


Piling (stacking) of wet timber (not kiln-dried) without sticks, even for a few days is a cause of staining and if prolonged, may result in serious losses from fungal decay.

Clout Nail

A type of galvanised nail with a large head, sometimes used as a decorative/period feature when face fixing solid boards.

Coastal Weathered

A surface effect on a wood floor that is created to replicate a riven, weathered textured appearance.

Coeffecient of Expansion

Timber expands and contracts with changes in moisture. The rate of this change varies according to a timber’s porosity. The rate of this change can be measured to produce a table showing the varying coefficient of expansion – it is measured by the change in the width of a board that happens when the moisture content goes from 20% to 10%. Beech has a high coefficient whereas Oak has a low one. In layman’s terms this could be called a timber’s “stability”.


We are careful to describe that our Architectural Details are made to complement your floor. This will not be a direct colour match, as the grain direction and finishing process in Architectural Details differs from a floor. Due to the complexity of certain finishes and tones, we are unable to provide hand-finished Architectural Details for a small selection of our portfolio.

Continuous Weave

A design pattern in wood flooring laid using squares and rectangles to resemble a weave pattern.

Coshh Sheet

The manufacturer’s guide to the safety aspects of the product, produced in accordance with the Control of Substances Hazardous to Health.


A process usually used at the end of the drying process used to create an equilibrium in moisture content.


A wide gap in the timber, often caused by shrinkage of timber containing a shake.

Crown Cut

A method of slicing veneers whereby the average inclination for the growth rings to the wider face is tangential or less than 45 degrees. This method is also known as flat cut.


Distortion of boards or blocks so that the surface is convex. Usually caused by very damp atmospheric conditions, whilst the subfloor remains dry.

Cumulative Shrinkage

Cumulative shrinkage or ‘rafting’ is caused by a lacquer applied to the surface of a floor, running down the edges of the pieces and sticking them together like strong glue (Side Bonding). When the floor shrinks (with its natural seasonal movement) instead of each piece shrinking a fraction so that there is a tiny gap between each piece, the pieces are stuck together in ‘rafts’ and wide gaps open at weak spots. It is sometimes possible to fill the gaps, but floors subject to bad cumulative shrinkage may have to be completely replaced.


Cupping is the opposite of crowning and is infinitely more common. It is almost always caused by moisture under the floor, whereby the moisture content of the bottom of the board is raised to a higher level than the surface, distorting the board. Whilst minor cupping, less than 0.5% of the board width, might be sanded out, there is a slight danger that, if the board should return to a stable form, crowning might result.

Damp Proof Membrane

A layer of impervious material, often polythene, built into the subfloor to prevent moisture affecting the flooring. Liquid DPMs are recommended when the existing moisture content of the screed is too high to fit a timber floor. BS8201 advises a slab moisture content of 4% or 75%RH. However, for flooring with a moisture content of 8 to 10% a slab must not exceed a moisture content of 2% or 40%RH. Residual moisture content in a newly laid concrete slab can be sealed with a proprietary product, but rising damp will need to be treated by a specialist.

Data Sheet

The manufacturer’s guide to the technical details of the product.

Db Value

The measurement of the floor’s sound insulative properties. Db = decibel – a unit of sound measurement. Measurement is usually divided into airborne sound and transmitted sound. There are various sound reducing underlays available that will significantly reduce the sound transmitted through the floor and into the room underneath. Choose the best underlay that will enable the use of a timber floor whilst meeting all of the current sound reduction regulations.

Differential Shrinkage

Different cuts of the same wood species can shrink at different rates. The most stable section is the quarter sawn section, this is far more stable than a plain sawn section. Different species of timber expand and shrink at different rates.

Dimensional Stability

This refers to the varying propensity of different wood floors to expand/contract. For example, wide engineered wood floors are more dimensionally stable than wide solid boards. Installation methods will/should reflect on a product’s dimensional stability.

Double Fumed

Double fumed is the process of fuming wood under high pressure that allows the fuming effect to penetrate deeply into the timber.

Drop Click (Drop Lock)

A type of Click jointing system for flooring where the headers (short ends) are joined together by a click system that allows the join to be made in a vertical “drop” method with the other board remaining flat. The long sides are generally joined together starting with an angle and then lowered and clicked into place. The headers can then be drop-locked together. Earlier Click systems required both long sides and headers to be angled when jointing together.


A pattern effect where the wood has been cut across the grain, rather than along the grain. Usually cut into square shapes and blocked together, the growth rings will be clearly visible. Although rather unstable in shape, the surface of end-grain timber is extremely hard and this makes it very special for wood flooring.

Ends Matched

Traditionally wood flooring would be supplied with the short ends just square cut and so not joined together when installed.  Nowadays it is normal for the ends to be “matched” by joining pieces together during installation aided by the application of a factory-machined tongue and groove or click system.


European Timber Regulation. Adopted throughout the EU (including the UK) in 2013. This legislation requires that all operators importing any timber, or products containing or derived from timber, from outside of the EU must carry out a recognised Due Diligence process to ensure its legality. This legislation has had a profound effect on the sourcing of timber and timber products resulting in a rapid decline in the range of tropical timber products now available.

Exotic Wood

In recent years, the real wood flooring specie of fashion choice has been predominantly Oak. This trend has seen the demise of many very good tropical species. Environmental and legality concerns around using tropical timbers has also seen their use in flooring, furniture and joinery products decline in favour of timbers from temperate regions. So nowadays any remaining tropical species used in wood flooring are regarded as Exotic. Care needs to be taken that any Exotic wood products do comply with all local and international legislation (including UKTR) and FSC certified products should be preferred.


Fair and average moisture content. Any moisture content is always an average of different readings across a batch of products, and this is why a spread of content is detailed – e.g. 8-10%. This figure is still only an average and therefore can still contain some boards with a higher or lower reading than 8-10%.

Face Nail

Boards nailed through the surface. Nails are usually punched and filled. Often necessary with boards exceeding 100mm in width in order to comply with the requirements of BS8201:1987 which states that boards exceeding 100mm in width should not solely be secret nailed. This requirement is now seen as being restrictive as widths up to 180mm are successfully secret nailed. In this instance, the humidity levels of both the sub-floor and air are crucial.

Fibre Saturation Point

This is the theoretical point when the cell cavities are empty of free water and the cell walls remain saturated. The average moisture content of wood at moisture saturation point is between 23-30%.


The beautiful appearance of the timber created by the grain and growth rings. Certain timbers have particular figures, e.g. the ‘bird’s eye’ figure in Maple medullary rays in quarter sawn Oak.


A fillet is a small batten (see above) often used on joists in order to pack up the floor level.


A finger joint, also known as a comb or box joint, is a method of joining smaller pieces of wood by machining thin, triangular fingers into the ends of each piece and then gluing them together under pressure. In this way many smaller pieces of wood may be joined together to create longer or wider pieces of wood.

Finished Profiles

Finished profiles are those which have been treated with colours, oils and lacquers to individually match or complement the flooring installation.

Fire Rating

European standard EN 13501-1 – ‘Fire classification testing requirements for floorcoverings’ refers to various performance levels of floor coverings. Most wood floor products when used as flooring will conform to a level of Dfl-s1. If clients require a standard higher or different to this, then individual type testing will be needed. The client will need to specify exactly which standard test method is to be employed and what level within the standard the floor must achieve.

Floating Floor

Wood flooring loose laid over a resilient underlay. Engineered or multilayer boards are usually laid as floating floors, but never solid hardwood boards. Floating floors laid over concrete must include a vapour barrier. The boards that constitute a floating floor must be fixed together, usually by gluing the tongues and grooves. Floating floors in domestic situations will usually be classed by insurance companies as part of the contents of a premise.

Floor finishes

The oils, lacquers and waxes that can be applied to the surface of the wood flooring to provide the best aesthetic choice combined with longevity and ease of maintenance.

Floor Seal

A heavy-duty lacquer applied to the surface of wood flooring. Usually maintained by sweeping and damp-mopping. Can be very hard wearing.

Formaldehyde emissions

Formaldehyde is a colourless gas with a pickle-like smell that can emanate from many types of floor coverings, detergents, paints and fabric. In very low levels it is harmless but in some cases of higher concentrations people may suffer allergic reactions, or irritation to eyes and nose.

Because of the glues and resins used in the manufacture process formaldehyde emissions are common from many types of laminate and LVT flooring, considerably lower in engineered real-wood flooring and very low or not at all from unfinished solid wood flooring.

Check that the product you buy confirms to E1 standards which say that acceptable formaldehyde emissions are an emission level better than .10 parts per million. That’s similar to CARB phase 2 standards, which say .11 parts per million is acceptable.


Forest Stewardship Council® – an independent, non-governmental, not-for-profit organization established to promote the responsible management of the world’s forests.

Fully Bonded

Fully bonded refers to an installation method whereby floors are installed fully glued down to a screed, plywood or concrete sub-floor. This method is especially recommended for larger areas where floating is not an option, or for engineered boards wider than 220mm. It is also the best method for fitting block, chevron or other patterns.

Subject to correct sub-floor preparation it is normal to use a high-quality MS Flex adhesive to glue the wood floor to the sub-floor. Glue must not be applied to the T&G and the correct expansion gaps must be respected.

In domestic property insurance situations, a fully-bonded floor will usually be considered as structural part of the premise and therefore part of the structure of the building.


Fuming timber, mainly European oak, is a process whereby the timber is exposed to large concentrations of ammonia gas. This has the effect of darkening the tannins in the wood surface leaving new timber with a nicely matured base colour. This allows oak flooring to be finished in a wide range of coloured options that would not be possible with un-fumed material.

Geometric Pattern

Wood floor designs made up of different shaped elements laid in a pattern that repeats across the floor. The sub-floor needs to be perfectly flat for these designs and the best results will be obtained installing as square-edge, unfinished components allowing for sanding and finishing on site.

Gloss Level

This refers to the degree of shine on the surface of a wood floor. It depends upon the type of lacquer or oil used to finish the floor.

Measured by a refractometer it is usually expressed as a %.

Typical values may vary between 8% gloss (quite matt and no shine at all) and up to 40% gloss (very shiny indeed). Most European oak floors are finished between 12% and 25% gloss.


There are various grades of timber, variously called prime, first, second, country, factory etc. There are no British standards or industry standards for wood floor grades – so you need to check what the grades include/exclude. Typical grade names used with wood flooring include, Prime, Nature, Rustic, Mixed, Tavern, Ungraded, etc. It is also important to remember that grades are species specific – e.g. Prime Oak might not contain either knots or sapwood but Prime Walnut might allow for some of both.


This is a general term for unseasoned timber. Green timber cannot ever be used internally for wood floors.


A term used to describe sandpaper, the lower the grit number – (e.g. 60) – the more coarse the paper. 60 grit is a common coarse grade used for removing the top few mm’s of wood from a floor. Typically, 150 grit would be used prior to applying oil to an unfinished floor and typically 320 grit being used in between lacquer coats.

Hand Polished Undulations

The process, made by hand, whereby undulating wood is carefully waxed and polished giving it a high degree of protection and maintaining a smooth, undulating surface. This is usually the best method for finishing outside-face Antique wood and Aged wood.

Hand Rolled Edges

This refers to the edge detail between the planks of wood flooring. After machining, the long edges of the floor would be left sharp. A traditional method is to soften those edges using a hand roller. Because the timber will vary in hardness along the edge, and because the roller is applied by hand, the result is a slightly irregular, very natural looking rounded edge detail between the planks. Much less uniform and more pleasing on the eye than any machine applied micro bevels.

Hand Scraped

In the 19th Century, before electrical orbital sanders came along, the traditional method for deep-cleaning or refurbishing wooden floors was to scrape off the dirt and oils from the surface of the wood using a hand-scraper. This resulted in characteristic lines of undulations in the floor.

Nowadays it can be common to similarly shape new wood floors by hand scraping the surface during manufacture, prior to applying the finishing coats.

Hardened Oil

A super-tough flooring lacquer with the appearance of a natural oil.

Hardwax Oil

Oil finishes are an ideal alternative to floor seals or lacquers, where a more natural appearance is desired. Oil finishes usually require marginally more maintenance than floor seals but, when properly maintained, can last longer. Hardwax oils can be easily re-coated and ‘spot repaired’. Please note that UV oil finishes are not compatible with hardwax oils. The closed surface of the UV finish restricts the hardwax oil from penetrating the wood – which results in drying difficulties as well as heavy residues left on the surface of the floor.

Header Joint

The joint between two ends of boards.


The core of the tree from which growth rings emanate.


A pattern of flooring made up from rectangular blocks. Typically the blocks may be of dimensions around 70mm x 350mm and will normally be glued down to a ply or a levelled screed.

Hit and Miss

When wood planks are sawn from the log, the action of the saw teeth leave saw-marks in the surface of the plank. After air drying and kiln drying, the shape of the planks will change further leaving undulations in the surface. It is normal for the dried planks to then be planed smooth by removing some mm from the top surface. If only a small amount of the surface is planed away then some areas will end up with a very smooth finish and the thinner parts of the plank will keep their original, un-planed surface. This effect is called Hit and Miss; a mixture of smooth-planed and un-planed parts on the same surface.


When wet wood is exposed to dry air it loses water to the air and when dry wood is exposed to humid/damp conditions it absorbs water and swells.


A device for measuring the moisture content of air. Hygrometers are calibrated in % relative humidity or RH. Hygrometers used in flooring consist of a polystyrene box about 300 x 300 x 75mm which traps air in a void under the box. The humidity box, as it is called, is fixed to a subfloor with an adhesive sealant strip and left for 12-60 hours. Moisture from the subfloor exchanges with the air above it until the two are in equilibrium, so that ascertaining the moisture content of the air under the box is the same as testing the screed itself. The British Standard code of practice for the installation of hardwood flooring (BS8201:1987) specifies that the RH should not exceed 75% when flooring is to be laid on a screed. With the modern practice of gluing boards directly to a screed, this is considered by many to be too high and 70% is more realistic for this purpose. As an alternative to humidity boxes, humidity sleeves are now in common use.


Interior checks caused when timber has been case hardened. The outer zones of the wood set without shrinking and when the centre core dries, it is restrained from shrinking and interior checks may result.


Feature of contrasting wood inset into a floor.


A layer of material, often built into the subfloor as a barrier for heat or sound.

Janka Hardness Rating

(See also Brinell Hardness rating)

The Janka method of testing the hardness of different wood types involves measuring the force needed to embed an 11.32mm diameter steel ball exactly half way into the surface of the wood.

The result is measured as a force in either lbf (pounds force) or N (Newtons). It is important to always include the units of measurement when quoting any Janka rating figures. Typical examples are: European Oak 1120 lbf (4980N) and Fir 620lbf (2760N).


A joist is a wooden strut, nowadays usually softwood, used to support floorboards to which the boards are usually nailed. The size of the joist will depend upon the expected load and the span.


A chamber in which the temperature, humidity and movement of air is controlled and is used to dry wood.

Kiln Dried

Timber for wood flooring is usually dried in a kiln to reduce its moisture content to 8-10%. This level is selected because it is the moisture content wood flooring usually assumes in buildings in the UK. In excessively dry conditions wood flooring will reduce to a moisture content of 5% – at this level significant gaps will appear, even in timber that has originally dried in accordance with British standards.


A knot is a figure in the grain of wood where a branch once grew, created during the growth of the tree. Small knots or burrs can be quite attractive. Some timbers, like Cherry, contain many knots; others, like Birch, very few. The knot content in timber can vary depending on the specific tree variety and is usually controlled in the grading process during production.


In a wood-flooring context, Lab harnesses the best in experimental creativity where innovation drives the development of pioneering new floors. A process bringing together the finest materials and truly innovative ideas.


Another name for floor seal. Lacquers are often polyurethane-based in a water-borne solution.


This is a plastic imitation wood flooring which has become popular in recent years, due mainly to its competitive pricing structure. However, whilst its general appearance is good, being produced photographically to look like wood, it lacks the warmth and resilience of real wood and cannot, of course, ever be sanded.


See Engineered Boards.

Latex Screed

When floor layers are faced with solid subfloors that are not sufficiently flat, they use a smoothing compound. Smoothing compounds, or as they are often incorrectly called, self-levelling compounds, are latex-cement powders which are mixed, either with water or latex paste, to form a grey cement which can be applied with a screeding trowel in thicknesses of 3mm, and in some cases even less.

Lye Treated

Lye for wood is a chemical preparation for priming unfinished or newly sanded interior woodwork and floors. The lye prevents the wood from yellowing and enhances the natural wood grain. Lye may be used on many types of wood and normally creates a pale-coloured wash effect.


Luxury Vinyl Tiles. Decorative flooring made from plastic. Many types of LVT are imitation copies of wood floors or ceramic tiles. Often only 3 or 4mm thick, these imitation floors may seem cheap or good value, but plastic products are very unstable in temperature change situations and the surface wear layers are measured in fractions of a mm. There are nowadays un-costed environmental issues with plastic flooring in terms of the CO2 impact of production and then surrounding the disposal of these short-life cycle products.

Plastic and laminate floors have a very limited life-span compared to real wood floor products that can be repaired, renovated, re-sanded and last a generation.

Micro Bevel

Very small bevel. See ‘bevel’ above.

Mixed width plank

A pattern of flooring installation where each row is a different width. Normally 3 widths of floor boards will be used, typically 80mm, 140mm or 180mm, and 220mm but there is no restriction and any installation can be tailored to reflect material availability.

Take care when installing to consider the pattern repeat and the visual impact of the mixed width rows.

Medullary Ray

Iridescent streaks found in quarter sawn material.


See ‘Engineered Boards’ above.

Moisture Content

The amount of moisture contained in a material. The moisture content of most wood flooring is 8-10%. The moisture content of a screeded subfloor when laying wood flooring ought not to exceed 40% RH which is about 2%.

Moisture Meter

A device used to measure the amount of water in a particular material. Moisture meters used in flooring are calibrated to a scale called ‘wood moisture equivalent’ (WME). This is because wood is fairly consistent with regard to moisture content, even within different species, whereas of the materials, like sand, cement or plaster, vary according to their particular composition. Consequently, they are measured on the WME scale which would be equivalent to the moisture content a piece of wood would assume if placed in contact with the material being tested.

Moisture Gradient

The variation in moisture content between the surface and the core of a piece of wood.


Movement is the swelling or shrinkage when wood is exposed to various humidity conditions. (See hydroscopic moisture)


There are various nailing machines on the market, perhaps the best known of which is Portanailer which drives nails into the flooring through the tongue at exactly the correct angle. Machines can be either manual or pneumatic.

Naked Skin Lacquer

This is a registered trade name for a floor lacquer with unique properties in that it is almost invisible when dry. After application it maintains the unfinished appearance of the wood and displays a gloss level of +/- 3%. It is a very hardwearing lacquer suitable for commercial applications.


A measurement of force. For the technically minded, it is the amount of force that imparts the acceleration of 1 meter per second to a mass of 1 kilogram.

Notched Trowel

The reason for applying adhesive (and other materials) with a notched trowel, is that the manufacturer of the product will have calculated the optimum quantity of adhesive required, and applying it with the correct notched trowel will ensure that exact quantity is applied, thus ensuring a perfect bond.


A preparation for finishing wood floors. (See also Hardwax Oil’). There are many different types of oil on the market. It is important to know the requirements of the floor and recommended maintenance procedure. Different oils have varying ‘high solid’ content. The high solids are the wax residues that are left once the ‘spirit’ (or carrying agent), has evaporated.

Oilwood Traffic

A branded wood floor finish that is actually a lacquer but has the appearance of an oil. Used in heavy foot-traffic areas.

Original Patina

Patina refers to the natural appearance that occurs on many types of surfaces, over time, because of reactions to chemicals in the air and surrounding environment. During the process of restoring antique woods to make reclaimed flooring, the original patina is often left as intact as possible allowing the provenance to show through.


Overlay is a non-structural flooring product that is usually glued down to a sound, level subfloor or existing floor structure. Normally the thickness is in the 8mm to 12mm range and the elements tend to be narrow planks (up to 90mm) and less than 1.0m long. Overlay is often laid in a herringbone pattern.


When wood is left exposed to the elements it changes colour due to an oxidation process whereby the tannins in the wood react with oxygen. Generally the wood will become darker in colour or, if exposed to sunlight too, it will bleach and become silvery-grey in colour. Bacterial action and wood decay also play a part in colour and structural change over longer timescales.

Natural environments are difficult to control and nowadays many chemical applications exist that can be applied to timber to change its colour or surface effect.

Parquet Flooring

Parquet flooring is formed from battens, usually 200-300mm x 60-100mm x 6mm or 10mm in thickness. Traditionally, parquet battens were face pinned and glued to wood subfloors, but today they can be laid over solid subfloors too. Traditionally laid in a herringbone pattern, but can be laid in many patterns and often with a border. Parquet flooring is also made in many elaborate patterns, eg Versailles. Parquet has also, incorrectly, become a generic term for wood flooring.

Pearl Lacquer

A high-build lacquer for wood floors displaying a subtle pearl-effect surface that allows the natural iridescence of the wood grain to show through.


Programme for the Endorsement of Forest Certification Schemes – An international non-profit, non-governmental organization dedicated to promoting sustainable forest management.

Pendulum Test

See Slip Rating.

Penny Joints

Often called ‘washer joints’, these are gaps left between every board, or every few boards, for additional expansion provision within the body of a boarded floor. They are called ‘penny’ or ‘washer’ joints because pennies or washers were used in order to achieve an even gap. Can also be left for decorative purposes to create a traditional/restoration look.


Small clusters of knots, that are collectively called Pips or burrs. The very heavy concentrations are called Burrs. Usually desired in Oak but also found in Elm and Sycamore. They are also mainly found in the United Kingdom, and rarely found in either Europe or North America. They can also be described as cat’s paws – as they look like the paw prints of cats.

Plain Sawn

The way the raw log is sawn into planks. The two most common formats are plain sawn and quarter sawn. Plain sawn material is the cheaper cut. The log is sawn into slices right across. Quarter sawing involves cutting each plank on the line of a radius from the centre of the log.


A laminated board consisting of thin layers of board bonded together. In flooring, 6mm ply is the most common for underlay purposes over, for example, a floorboard subfloor. Ply can be resin-bonded or WBP (water and boil proof) which means the ply should be unaffected by moisture.


See nailer.

Prime (grade)

This normally refers to the grade of timber used in wood floors. Prime grade products will normally have very few knots and minimal colour variation. The exact grading rules will vary from supplier to supplier and will be species dependent too. Check the details in the small-print !


GE-Protimeter are one of the world’s leading manufacturers of moisture-testing equipment. They manufacture hygrometers (see ‘hygrometer’ above) as well as moisture meters (see ‘moisture meter’ above).


A quarter-round beading used in flooring installations to cover the allowed expansion gap. It is usually the same species of timber as the floor, or as near in shade as possible, and is pinned to the skirting.

Quarter Sawn

True quarter sawn Oak boards are cut so that the end grain is at an angle of 90 degrees to the face board. This produces wonderfully straight grained planks. Medullary rays (the iridescent streaks) are then visible as swirls running across the width of the board. The joinery in cathedrals, palaces and fine houses was produced from the finest quality quarter sawn Oak.

Random Length

Boards which vary in length within one floor.

Random Width

Boards which vary in width within one floor. Historically through and through, cut planks produced lots of different widths of boards.


See Cumulative Shrinkage.

Rare Finds

A discovery of wood where the available quantities are limited. Usually brought in from former colonies during the Industrial Revolution, this wood typically served its time in warehouses and public spaces before being lovingly restored by expert craftsmen into floors, walls or ceilings ready for a new life and new adventure.


Not to be confused with Antique!. Reclaimed refers to those floors manufactured using restored wood that had been used previously.

Relative Humidity

Humidity in the air is measured using an hydrometer. The amount of moisture air can contain varies according to its temperature. Warm air can hold more moisture than cool air. Warm air gives up its moisture as it cools, so that if warm air comes into contact with a cool surface, we get condensation. The measurement of the quantity of moisture in air is expressed relative to its maximum capacity to contain moisture which would be 100% relative humidity.

Rift Sawn

As per quarter sawn but with an angle of just under 90 degrees – producing straight grained boards without the medullary rays.

Residual Dampness

Moisture remaining within a screed even though the surface appears dry.

Restoration Oil

An oil-based wood floor finish giving a warm natural appearance.


A slight irregularity in the surface of a hardwood floor often caused by inefficient sanding.


An unusual type of figure that looks like a ripple across the width of a plank. Highly prized and found in Maple and Sycamore.

Rising Damp

Occurs in screeds that do not have an effective damp proof membrane. Sub-floor preparation products that pre-seal damp screeds will not (in the long run), stop damp from affecting a wood floor.


Normally refers to the grade of timber being used in the flooring. Rustic grades tend to be more knotty including dead knots, more colour variation and with splits and other features. The exact grading rules will vary with species and depending upon the supplier. Check the small print!

R values

See Slip Test.


A sample is one of a number of pieces set in a kiln or air-drying stack used to measure the loss of moisture.


To grind the surface of a wood floor with sandpaper so as to smooth the surface ready for the application of a dressing. Usually carried out using a sanding machine.

Sand Blasted

Sand blasting is a traditional method, still often used today, of removing paint, oxidised wood and decay from the surface of wooden structural beams in buildings.

The result is to restore the beams back to their former glory and in a bright and clean state.

The surface effect it leaves on the beams can be reproduced on wood floor planks leaving a unique surface texture, markedly different from brushing or sanding.


Sapwood is the younger softer living outer portion of the tree that lies between the cambium and the heartwood and is more permeable, less durable, and usually lighter in colour than the heartwood. Visible as the light timber on the outer edges of the planks, sapwood doesn’t fume and makes for a great design feature.


A beading, used for the same purpose as a quadrant bead (see above) but concave shaped instead of convex shaped.


Usually refers to the subfloor, which may be a sand and cement screed. Must be dry (below 75% relative humidity) before wood flooring is laid on it. Must be sound and flat too. May also be a latex or other smoothing screed.

Screeding Trowel

A trowel with a smooth surface and without notches for applying sand and cement, latex or other smoothing screeds.


Similar to sanding, but usually done with a rotary disc using very fine abrasives. Ideal for sanding old floors when you want to carefully remove layers of patina.


Common name for polyurethane-type lacquers applied to wood flooring.


The process of drying timber either naturally or in a kiln, to a moisture content appropriate for the conditions and purposes for which it is to be used. For hardwood flooring in the UK, this usually means 8-10% moisture content. ‘Seasoned timber’ is also used as a description of timber that has been air dried for a long time.

Secret Nail

The method of nailing tongued and grooved boards through the tongue so that the nails cannot be seen in the finished floor. See also ‘Portanail’ above. Note that BS8201:1987 states that boards of less than 100mm in width can be secret nailed as their sole method of fixing.

Screw & Plug

The method of concealing screws used in face-fixing wood flooring. The screw is countersunk below the surface of the board and a plug of the same grain and shade as the board is fitted over the screw.

Self-Levelling Compound

See latex screed.

Serrated Trowel

See notched trowel.

Shadow Sawn

This is a trade-marked name for a particular pattern on a wood floor surface which allows slight traces of the original saw-marks to remain visible.


A natural defect in a board, shakes are small cracks in the material. They are unavoidable in many species and may open when the board shrinks.

Shou Sugi Ban

The painstakingly intricate process involved that pays homage to this ancient Japanese tradition of preserving wood using fire. Boards used to manufacture these floors and panels are individually charred by flame in carefully controlled conditions to enable this unique surface effect.


When wood dries the removal of moisture causes the wood to shrink. Shrinkage normally starts at fibre saturation point (25/30%). All timber shrinks more tangentially than it does radially whereas shrinkage longitudinally is negligible. As a result of the different shrinkage rates radial and tangential, you get different shrinkage which will cause square timber to diamond, but if wood shrank evenly in each section, this would not happen. Every species of wood has a different rate of shrinkage.

Skip Sawn

(See also Hit and Miss) A surface effect on a wood floor where saw marks remain on certain patches of the surface and other patches are smooth.


The wooden board (usually) fixed to the bottom of walls. If the skirting is removed before the laying of the floor, the required expansion gap can be left underneath so that no additional beading is required. Various moulded profiles are available, including pencil round, torus, lambs tongue, etc.

Slip Rating

Wood floors are often used in public spaces and so it is important to know how slippery they may be to assess the risk of slips and falls.

There are 2 main test types referred to in the UK.

(i) The DIN system  according to DIN 51130. This method involves the use of a mechanical ramp that is gradually increased in angle until the point that a person wearing shoes with a safety sole will slip. Various contaminants can be introduced such as oil, water, soap etc. The results will be expressed as an R value typically between 9 (most slippery) and 13( least slippery).

(ii) The Pendulum test according to BS7976. In this simple and portable test a swinging, imitation heel (using a standardised rubber shoe sole sample), which sweeps over a set area of flooring in a controlled manner. The slipperiness of the flooring has a direct and measurable effect on the pendulum test value (PTV) given.  Contaminants such as water or dust can be introduced as this will have a marked effect on the slip rating of the floor. PTV values 0 to 24 show high slip potential; 25 to 35 moderate slip potential and 36+ low slip potential.

Smoothing Screed

A powder, often cementitious, mixed with either water or a latex paste, depending upon its type, and used to prepare uneven screeds to a smooth surface. Often called a levelling or self-levelling screed, but this is incorrect as it is very difficult to level floors with such a product. There are companies who pump similar materials onto floors and this procedure will actually form a level base.

Spalted Beech

Spalting is the result of fungi growing on the tree. The black lines are the result of the roots of the fungi dissolving the wood in order to feed on the nutrients released. It affects both the colour of the wood and the hardness.


Stone Plastic Composite. A plastic floor, similar to LVT and WPC. Although more stable than a WPC floor, SPC floors are extremely heavy for their thickness and face the same environmental issues.

Square Shoulder

This normally refers to the edge details between planks of wood flooring. It is in contrast to bevelled and other edge details. Normally square-shoulder flooring will be supplied un-finished and is intended to be sanded flat on site prior to finishing. It will then give the appearance of a “seamless” smooth floor with flat joints between the planks or pieces. Pre-finished square-shouldered floors are available in smaller sizes, typically herringbone, but great machining accuracy and very flat sub-floor preparation is necessary if lipping is to be avoided between pieces.

Steaming, Fuming and Heat Treating

Processes often used on timber, especially Oak. The procedures both darken the timber and strengthen it.

Sterling Board

A type of particle board, used for subfloors.

Stick Marks

When wood is stacked for drying, sticks are placed between the boards to enable air to circulate all round. Sometimes these sticks cause marks in the timber itself. This is usually when the wrong species of stick has been used that causes a reaction with the boards being dried.


The surface onto which the decorative wood flooring is laid.

Super Matt lacquer

This usually refers to the degree of gloss level displayed by the floor. Typically 5% to 10% gloss level.


Wide-board, long planks in super-prime grade oak. Only 1 in 1000 boards can be selected as Superfine.


A term used to include really broad planks and oversized herringbone elements that deliver discreet style, underpinned with design that unites luxury and performance. Made from nature grade European oak boasting a sturdy 6mm wear layer the Superwide products are a combination of statement with majestic hues and high-end finishes.

Surface DPM

If screed is tested with a hygrometer (in accordance with BS8201) and found to be wet, a surface DPM might be used, subject to circumstances. Such products may be liquids, eg epoxy DPMs, or underlays, such as System Platon or Uzin interlayers. Also consider Ted Todd Primerfast for a rapid DPM sealing of concrete sub-floors.

Sustainable Source

A source of wood flooring where the forest is sustainably managed. Wood floor products by their very nature are amongst the most environmentally friendly floor covering products. As trees grow they capture carbon from CO2 in the atmosphere and this is then fixed in the wood. Using that wood for flooring products then keeps that carbon trapped and more trees grow capturing more carbon from the CO2 in the atmosphere.

Tar or Bitumen-Centre Building Paper

Used over wooden subfloor as a vapour barrier. Whilst nails puncture polythene, the bitumen centre in this material clings to the nails. It is now accepted that floors laid on joists that are vented should be laid on building paper.


Thermo wood is produced by heat treating timber to high temperatures, often in excess of 200 degrees centigrade, in the absence of air. During the heat treatment, chemical and structural changes occur within the timber which alter and improve some of its basic characteristics. The resulting product is a darker-coloured and more durable, stable timber, an ideal cladding material for use in exposed areas such as external walls.

Threshold Strip

A piece of shaped wood, placed in a doorway so that a higher level wood floor can be smoothly finished to a lower adjoining floor.

Tongue & Groove

A method of joining individual pieces of wood together in a floor to form a homogeneous unit. The tongue is cut from the edge of the block or strip to project outwards. The groove, in the opposite side is made to fit the tongue snugly, but not too tight. Tongues and grooves are always on the long edges; if they are on the ends as well, the material is said to be “ends matched”. In floating floors, where tongues and grooves are glued together, the groove has a void at the inside to accommodate the glue and prevent it from being squeezed to the surface. The tightness of the tongue and groove is called the tolerance. There is no industry standard for the amount of tolerance in a tongue and groove joint.


A strip placed in a doorway between two adjoining wood floors of the same level. Permits the inclusion of an expansion gap in the doorway.


An underlay is a barrier that sits beneath a wood flooring and serves a variety of purposes. An underlay is essential when floating a floor but not normally used in a glue-down installation.

The correct and best quality underlays will serve to improve a flooring installation through the following factors:

  • uneven sub floors
  • moisture barrier
  • sound reduction
  • heat insulation
  • heat transmission (under-floor-heating)

The choice of underlay will depend upon the importance in the installation of the factors above.

Cheap poly-foam underlays 1 or 2mm thick are not normally recommended in real-wood floor installations. They offer minimal benefit with the factors above and over time will compress and lose their effectiveness. Always choose the best underlay for the job !

The best wood floor underlays are typically 3mm to 5mm thick, often have an integral aluminium moisture barrier and will be made of high-density PU or rubber to ensure a long life not affected by pressure-collapse.

High-grab pressure-sensitive self-adhesive rubber underlays are also available that allow floating installations with the advantages of a fully-bonded installation.


When wood planks are sawn they emerge from the saw with a predominately flat face, usually with marks made from the teeth of the saw on the surface. (Saw marks.)

Through time as the timber is allowed to dry out and as the natural tensions within the timber relax this results in an undulating (not flat) surface. This effect is particularly noticeable around the knots and heart of the planks as these areas dry out at a different rate.

Genuine antique wood will often show these undulating features because of the age and history of the wood and it is a feature to look for in hand-made floors.

UV Dried

A method of rapid-drying lacquer in the factory which produces a harder wearing surface. Modified oils can also be UV dried.

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A paste applied to the floor surface which protects the wood from traffic wear. Superseded in the 1980s by polyurethane and other lacquers and due to the latter needing less maintenance, it is now rarely used but substituted by Hardwax Oil. Waxes improve the lustre of a floor and are used to create a period, restored feel. Several coats are applied to build up the finish, which is then polished either mechanically or by hand to create a warm, shiny floor.

Wear Layer

The top layer of wood nearest the surface in a multi-layered board which receives the foot traffic. Wear layers are normally quoted on a “nominal” thickness basis– this means the thickness before sanding. A wear layer can also be measured on a solid board as being the thickness of wood above the tongue. The quality of an engineered floor is broadly in line with the thickness of the wear layer. For the very best quality floors look for a full 6mm thickness wear layer.  4mm thickness wear layers are suitable for most domestic applications. Be aware that many floors are available on the market with only 2.5mm, or less, wear layer. Check the wear layer thickness before buying. You do generally get what you pay for. Also, be aware of  wood floors with 0.6mm veneer wear layers. They may look like wood, but they will not have the quality or longevity of floors with 4mm or 6mm wear layers.

Laminate and plastic (LVT) floors also have “wear layers”. These are normally thin melamine sheets pressed into the boards. They are only fractions of a mm thick. In better quality laminate or LVT floors these wear layers can be quite hardwearing against normal foot-fall abrasion, but any repairs to scratched or damaged floors are very difficult or impossible to effect. Compare this to real wood flooring with 4mm or 6mm wear layers where any repairs or re-work are possible allowing the product to last for generations.

Weathered Patina

(See Patina). In addition to acquiring a patina when exposed to weather, wood often becomes eroded too by a variety of causes including bacterial action, action of water, ice, wind or even sandblasting. Weathered Patina wood may exhibit many of these characteristics.


Wood Plastic Composite. A type of plastic flooring, normally 4 or 5mm thick with a click-jointing installation system and often with an integral noise-reducing underlay. This product is fast to install and many designs are available, including copies of wood and stone designs.

Although not badly affected by moisture, WPC floors do expand and contract with temperature and suffer similar problems to other plastic floors (See LVT).

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2-Part floor finishes

In the installation and finishing of wood flooring, technology is moving on and better floor finishes are being developed all of the time. The use of solvent-based products is in decline too. Nowadays the best possible floor finishes (easiest application, best appearance and wear properties) are 2-part, meaning that before application 2 components are mixed together. Normally these finishes are water-based or 100% solids meaning that there will be no harmful vapours during or after finishing.


Most wood flooring has a flat or slightly undulating surface.

Wall panelling however, can allow many more shapes and often the surface can be made from many different sized pieces resulting in a truly 3-dimensional product.

100% Solid

This is a term that is usually applied to lacquers, oils and other surface preparations used in wood floor finishing. Traditional forms of these products required that they “dry”, usually by the evaporation of a solvent. This would reduce the mass of product left on the surface.

In a 100% solid product, there will be no evaporation meaning that if 100 grams of product is applied, the same mass will remain when dry or cured.