ACCLIMATISATION
When acclimatising a wood floor, the boards should be separated and laid loosely to enable the air to circulate around them. This procedure should be located in the area where it is to be installed to enable it to ”acclimatise” or adjust its moisture content to correspond with its surroundings.
ADHESIVE
We recommend that you use a notched trowel with the correct size notches so as to apply the correct quantity of adhesive. Used for fixing flooring to a sub floor.
ADHESION
Bonding of one material to another. Could be affected by the conditions of the surfaces to be coated, the closeness of the contact, temperature and humidity. We recommend that adhesives should be solvent and water free.
APPLICATOR
Used for applying adhesive, oil, and seal.
ARCHITRAVE
Used for doorways or perhaps the good old dado rail. The product usually requires undercutting to permit wood flooring the fit underneath. Various moulded profiles are available including – Pencil Round, Taurus, Ogee and B Modern.
BATTEN
Pieces of softwood, which supports the hardwood flooring, generally fixed by nailing.
BEVEL
A decorative feature whereby only the length of the board is bevelled. The bevel more clearly defines the boards edge, sometimes this is also called an ‘eased’ edge or ‘chamfer’. There is no standard bevel size, this will vary per supplier, and it is usually angled at 45o to a maximum of 2mm deep. No charge is incurred for this service but if required stated at the time of placing your order.
BLEACH
A chemical is applied to timber to appear lighter in colour. Certain hardwoods are bleached by sunlight.
BLOCKS OF PARQUET WOOD BLOCKS
Timber flooring varying in size but usually in the region of 200 – 350mm x 50 – 75mm x 20mm. The blocks are supplied in packs with one tongue and three grooves. These are American sizes designed for basket weave, Herringbone and other patterns and is adhered to a screeded sub floor with adhesive.
BOARDS (or PLANKS or STRIPS)
Wood flooring comprising of 95-200mm in width and from 1500-3000mm in length. Boards can be secret nailed (we recommend up to 140mm) or glued. We recommend that solids are not suitable for a floating floor but the onus is on you.
BORDER
A featured floor whereby a contrasting timber is inset around the perimeter.
BRINNELL SCALE OF HARDNESS
A scale that compares the hardness of various species of timber.
CHIPBOARD
Made from particles of wood, mechanically compressed with glue or other binders to produce a board. Commonly used as a sub floor particularly in new construction, avoid damp conditions unless you source flooring grade chipboard that is dam proof.
CLOSE - PILLING
Piling (stacking) of wet timber (not kiln dried) without sticks, even for a few days can cause staining and if prolonged, may result in serious losses from fungal decay.
CLOUT NAIL
A type of galvanised nail with a large head, used when face fixing solid boards.
COEFFECIENT OF EXPANSION
All timbers expand and contracts with change in moisture depending on the timbers porosity. The rate of which can be measured by producing a table showing the carrying coefficient of expansion – it is measured by the change in the width of a board that happens when the moisture content foes from 20-10%. Oak has a low coefficient whereas Beech is high. In layman’s terms this could be called a timbers ‘stability’.
COSHH SHEET
The manufacturers guide to the safety aspects of the product, produced in accordance with the control of substances Hazardous to Health.
CONDITIONING
Used at the end of the drying process to create equilibrium moisture content.
CRACK
A gap in the timber, caused by the shrinkage of timber containing what is knows as a ‘shake’ in the board.
CROWN CUT
The method of slicing veneers whereby the average inclination for the growth rings to the wider face in tangential or less than 45◦ (also known as a flat cut).
CROWNING
Distortion of boards or blocks so that the surface is convex caused by very damp atmospheric conditions, whilst the sub floor 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. (Please note that Millennium’s solid wood floors are finished by lacquering the entire board, top, bottom, length and edges.) 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
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 sub floor 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. BS8201advises slab moisture content of 4% or 75% RH. However, for flooring with moisture content of 8 – 10% slab must not exceed 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 manufacturers guide to the technical details of the product.
Db VALUE
The measurement of the floors sound isolative properties. Db = decibel – a unit of sound measurement. There are various sound reduction underlay available that will enable the use of 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 ¼-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 products dimensional stability.
ENDS MATCHED
The tongue & groove profile along the length and ends of the board. This profile on structural flooring enables individual planks to straddle a joist, rather than being cut back to end on an individual joist, which is wasteful.
ENGINEERED (BOARDS)
Due to their cross-grained construction Engineered boards can be laid as a floating floor, because they are very stable. Structural engineered boards are now also available; they are made with plywood backing. Our boards have a wear layer of 6mm Oak and 15mm Waterproof Birch Plywood. Engineered Boards are ideal for underfloor heating. Our boards differ in as much as the board is planed both top and bottom ensuring that each board is exactly 21mm in thickness.
EXPANSION
Wood is hygroscopic material. It expands only due to the absorption of moisture, and shrinks when it loses moisture. In the UK, the moisture content of wood flooring is at its highest in summer, when windows and doors are open and the air relatively moist; it is at its lowest in winter, when windows and doors are closed and central heating is on full, creating very damp air. A moisture content of 8-10% assumes a humidity level of 35 to 65%. So if during winter you fail to ‘air’ your rooms and the humidity drops to fewer than 35% shrinkage will occur – at 20% major damage to all floors is evident (even engineered).
EXPANSION GAP
A gap left at the perimeter of a wood floor to allow for seasonal expansion. The gap is usually 15mm or 3mm per linier m across the grain.
F.A.M.C
Fair and average moisture content. And moisture content is always an average of different readings across batch products, and this is why a spread of content is detailed – i.e. 8-10%. This figure is still only on 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. 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 SATUARTION 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%
FIGURE
The beautiful appearance of the timber created by the grain and growth rings. Certain timbers have particular figures, e.g. the ‘birds eye’ figure in maple or medullar rays in ¼-sawn oak.
FILLET
A fillet is a small batten often used on joists in order to pack up the floor level.
FLOATING FLOOR
Wood flooring loose lay 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.
FLOOR SEAL
A heavy-duty lacquer applied to the surface of wood flooring. Usually maintained by sweeping and damp mopping. Can be very hardwearing.
GRADING
There are various grades of timber, variously called prim, 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. It is also important to remember that grades are species specific – i.e. Prime oak might not contain either knots or sapwood but Prime Walnut might allow for some of both.
GREEN
This is the general term for unseasoned timber. Green timber cannot ever be used internally for wood floors.
HEADER JOINT
The joint between two ends of the boards.
HEART
The core of the tree from which growth rings emanate.
HYDROSCOPIC
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.
HYGROMETETER
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 75 mm, which traps air in a void under the box. The humidity box, as it is called, is fixed to a sub floor with an adhesive sealant strip and left for 12-60 hours. Moisture from the sub floor 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 the 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 the purpose. As an alternative to humidity boxes, humidity sleeves are now in common use.
HONEYCOMBING
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.
INLAY
Feature of contrasting wood inset into a floor.
INSULATION
A layer of material often built into the sub floor as a barrier for heat or sound.
JOIST
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.
KILN
Millennium Hardwood Ltd has the largest kiln capacity in the North of England. This is where the temperature, humidity and movement of air are controlled on a kilning cycle taking approximately 3 weeks to dry wood.
KILN DRIED
Our wood flooring is dried in our kiln to reduce its moisture content down to 8% to 10%. This level is selected because it is the moisture content wood flooring usually assumes in buildings in the UK.
KNOT
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.
LACQUER
Another name for floor seal. Lacquers are often polyurethane – based in water – borne solution.
LATEX SCREED
When floor layers are faced with solid sub floors 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 thickness of 3mm, in some cases even less.
MICRO-BEVEL
Using the latest technology, our machinery places a small bevel along the length of board and you need to state this requirement at time of ordering.
MEDULLARY RAY
Iridescent streaks found in a quarter-sawn oak.
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 sub floor when laying wood 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’ This is because wood is fairly consistent with regard to moisture content, even within different species, whereas other 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
Movement is the swelling or shrinkage when wood is exposed to various humidity conditions.
NAILER
There are various nailing machines on the market, perhaps the best known of which is portanailer, which drives nails into the floating at exactly the correct angle. Machines can be either manual or pneumatic.
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.
PARQUET FLOORING
Parquet flooring is formed from battens, usually 200 – 300mm x 60 – 100mm x 22mm in thickness. Traditionally, parquet battens were face pinned and glued to wood sub floors, but today they can be laid over solid sub floors too. Traditionally laid in a herringbone pattern, but can be laid in many patterns and often with a border.
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.
PIPPY
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. It is also mainly found in the United Kingdom and is rarely found in either Europe or North America. They can also be described as cat 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 the radius from the centre of the log.
PLY
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 sub floor. Ply can be resin-bonded or WBP (Water and boil proof) which means the ply should be unaffected by moisture.
PROTIMETER
GE-Protimeter is one of the worlds leading manufacturers of moisture-testing equipment. They manufacture hygrometers as well as moisture meters.
QUADRANT
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.
QUARTER SAWN
True quarter sawn boards are cut so that the end grain is at an angle of 90◦ to the face board. This produces wonderfully straight gained planks. Medullar rays 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
Here at Millennium Hardwood Ltd we offer a length specification ranging from 1500-3000mm depending on specie.
RANDOM WIDTH
Boards, which vary in width within one floor. Historically through and through, cut planks produced lots of different widths of boards.
RELATIVE HUMIDITY
Humidity In the air is measured using a 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◦ - producing straight-grained boards without the medullar rays.
RESIDUAL DAMPNESS
Moisture remaining within the screed even through the surface appears dry.
RIPPLE
A slight irregularity in the surface of a hardwood floor often caused by inefficient sanding.
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.
SAMPLE
A sample is one of a number of pieces set in a kiln or air-drying stack used to measure the loss of moisture.
SAND
Carried out using a sanding machine to grind the surface of a wood floor so as to smooth the surface ready for the application of a dressing.
SAP
The liquid part of a tree. Visible as the light timber on the outer edges of the planks.
SCREED
Usually refers to the sub floor, 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 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.
SEAL
Common name for polyurethane –type lacquers applied to wood flooring.
SEASONING
The process of drying timber either naturally or in the 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. 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.
SHAKE
Natural defects in a board; shakes are small cracks in the material. They are unavoidable in many species and may open when the board shrinks.
SHRINKAGE
When wood dries the removal of moisture caused 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 that 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.
SKIRTING
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, Taurus, Ogee and B Modern.
SMOOTHING SCREED
A powder, often cementations, 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.
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 particleboard, used for sub floors.
STICK MARKS
When wood is stacked for drying, sticks are places 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.
SUBFLOOR
The surface onto which the decorative wood flooring is laid.
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, e.g. epoxy DPM’s, or underlay, such as system Platon or Uzin interlayer.
SUBSTAINABLE SOURCE
A source of wood flooring where new trees are continuously planted to replace those cut down.
TAR OR BITUMEN – CENTRE BUILDING PAPER
Used over wooden sub floor as a vapour barrier. Whilst nails puncture polythene, the bitumen centre in this material clings to the nails. It is accepted that floors laid on joist that are vented should be laid on building paper.
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 tolerance. There is no industry standard for the amount of tolerance in a tongue and groove joint.
T- BAR
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.
UNDERLAY
A material placed under a wood floor to smooth the sub floor (e.g. ply), to protect against damp (e.g. Polythene) or as a resilient layer under floating floors. Can also help to cut down airborne noise.
UV DRIED
A method of rapid-drying lacquer in the factory that produces a harder wearing surface. Modified Oils can also be UV dried
WEAR LAYER
The layer of wood nearest the surface in a multilayer 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
Tel: 0800 652 2475
