wood flooring advice
Glossary Of Terms
A wooden frame used around doorframes to hide the gap between the frame and the plastered wall. Both doorframes and architraves may require undercutting to permit wood floors to fit underneath.
A decorative feature in floor planks whereby the edge of the board is planed off. The bevel is usually used to clearly define the edge of each plank. The size of bevel may vary from producer to producer, however it is usually between 0.5mm and 2mm deep and angled at 45 degrees.
Usually a feature in parquet flooring whereby, a contrasting timber is inset around the perimeter of a room.
BRINELL HARDNESS TEST
A hardwood flooring hardness test which involves pressing a 10mm steel ball against the hardwood flooring. The method is used worldwide on wood as well as metal.
A board made from particles of wood, mechanically compressed and bonded to produce a flat board. Although basic chipboard is a common subfloor material today, it should be avoided in damp conditions unless specified as damproof flooring grade. Serrated nails should be used when fixing, as chipboard does not retain standard nails or pins well.
A method of joining boards together without the use of glue. The tongue is made with a protrusion that fits over a corresponding rebate in the groove.
COEFFICIENT OF EXPANSION
Timber expands and contracts with changes in moisture while the rate of change varies according to the timbers porosity. The rate of moisture change can be measured to produce a table showing the ‘varying coefficient of expansion’ and is measured by the change in the width of a board that when the moisture content goes from 20% to 10%.
A distortion of floor boards or blocks producing a convex in the surface and is usually caused by very damp atmospheric conditions, whilst the subfloor remains dry.
Cupping is the opposite of crowning and is almost always caused by moisture content below or at the bottom of the board causing the edges to be raised to a higher level than the surface.
DAMP PROOF MEMBRANE (DPM)
A layer of impervious material, often polythene, fixed to or under the subfloor to prevent moisture affecting the floor. DPMs can also come in liquid format and are usually used 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.
Also called “Multilayer”, these boards are constructed using several layers which usually consist of a 4mm or 6mm hardwood surface top layer, a softwood core at right-angles to the hardwood or plywood and a ply backing. Engineered boards are far more dimensionally stable than solid boards and as such can be installed using the “floating floor” method.
Wood is a hygroscopic material. It expands due to the absorption of moisture, and shrinks when it loses moisture. In the UK, the moisture content of wood is highest in summer, when windows and doors are open and the air is relatively moist; and is at its lowest in winter, when windows and doors are closed and central heating is running on full, creating a very dry air. Conditions are best kept at a moisture content of 8% to 10% and humidity level of 45% to 65%.
A gap left at a doorway or the perimeter of a wood floor to allow for seasonal expansion. The gap is usually 6-10mm wide or 3mm per linear across the grain.
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 (i.e. 8% to 10%). This figure is still only an average and therefore can still contain some boards with a higher or lower reading than.
Boards nailed through the surface of the plank. Nails are usually punched and filled.
Wood flooring loosely laid over a resilient underlay. Engineered or Multilayer boards can be laid as floating floors, but not solid hardwood boards. Floating floor boards 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 together.
A hard wearing, heavy-duty lacquer applied to the surface of wood flooring.
FUMING / SMOKING
Fuming is a traditional process for darkening and enriching the colour of wood, mainly oak, by oxidation of naturally occurring tannins in the timber using Ammonia. The physical change in appearance is subject to the tannin and other natural content held within the structure of the timber and its interaction with the treatment. The treatment forms an envelope around the surface of the board and depth of penetration will vary subject to the timber structure however the outward appearance of the edges could suggest the boards are treated through.
Where a more natural appearance is desired, oil finishes can provide an ideal alternative to floor seals or lacquer. Oil finishes usually require marginally more maintenance but when properly maintained, can last longer and can be easily re-coated and “spot repaired”.
A device for measuring the moisture content in the air. Hygrometers are calibrated in % relative humidity or RH.
A layer of material often built into the subfloor as a barrier for heat and/or sound.
A wooden strut (usually softwood) used to support the floorboards/subfloor to which the wood flooring planks are usually nailed. The size of the joist will depend upon the expected load and the span.
Timber for wood flooring is usually dried in a kiln to reduce its moisture content to 8% - 10%. This level is ideal as it is the moisture content typically assumed by wood flooring in UK buildings.
Smoothing compounds are latex-cement powders which are mixed, either with water or latex paste, to form grey cement and are primarily used for levelling purposes.
A very small bevel. See Bevel above.
The ammount of moisture contained in a material. The moisture content of most wood flooring is between 8% - 10%. The moisture content of a screeded subfloor when laying wood should not exceed 40% RH which is about 2%.
Movement is the swelling or shrinkage of wood when it is exposed to various humidity conditions.
There are various types of nailing machines on the market, but perhaps the best known of which is the Portanailer. These machines drive nails into the flooring at exactly the correct angle and can be manual, electric or pneumatic.
A preparation and/or coating product for finishing wood floors. There are many different types of floor oil on the market and it is important to know the requirements of the floor and recommended maintenance procedure.
Parquet flooring is formed from battens, usually 200-300mm long, 60-100mm wide and 6-10mm thick. Traditionally parquet battens were faced pinned and glued to wood subfloors, but today they can be laid in many elaborate patterns.
A board consisting of thin layers of board bonded together and is commonly used as subfloor.
Ply can be resin-bonded or WBP (water & boil proof) which means the ply should be unaffected by moisture.
A quarter-round beading used in flooring installations to cover the expansion gap between the floor and the wall or skirting-boards. It is usually from the same species of timber as the floor, or as near in shade as possible.
True Quarter Sawn oak boards are cut so that the end grain is at an angle of 90° to the face board. This produces wonderfully straight grained planks and iridescent streaks are visible as swirls running across the width of the board.
Moisture remaining within a screed even though the surface appears dry.
Occurs in screeds that do not have an effective Damp Proof Membrane (DPM) or walls without a proper Damp Proof Course (DPC).
A concave beading used in flooring installations to cover the expansion gap between the floor and the wall or skirting-boards. It is usually from the same species of timber as the floor, or as near in shade as possible.
Usually refers to a sand/cement, latex or other smoothing subfloor. It is extremely important that the screed is sound, flat and dry (below 75% relative humidity) before wood flooring is laid on it. Must be sound and flat too.
Common name for oils-based or polyurethane-type lacquers applied to wood flooring.
The process of drying timber either naturally or in a kiln, to moisture contents appropriate for the use of the material. For hardwood flooring in the UK, this usually means 8% - 10% moisture content.
The method of nailing tongued and grooved boards through the tongue so the nails cannot be seen in the finished floor.
SCREW & PLUG
The method of concealing a face-fixed screw with a wooden plug. 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
When wood dries the removal of moisture causes the wood to shrink. Shrinkage normally starts at Fibre saturation point (25/30%). Every species of wood has a different rate of shrinkage although all timber shrinks more tangentially than it does radially whereas shrinkage longitudinally is negligible.
The wooden board usually fixed at the bottom of walls in its connection with the floor. Various moulded profiles of skirting exist including- pencil round, torus, ogee, etc...
STEAMING AND HEAT TREATING
Processes often used on timber, especially Oak where the procedures both darken the timber and strengthens it.
The surface onto which the decorative wood flooring is laid
If a screed which has been tested with a hygrometer (in accordance with BS8201) is found to be with higher levels of moisture then recommended, a surface DPM might be used. Such products may be liquid or a plastic underlay.
A source of wood flooring where new trees are continuously planted to replace those cut down.
TONGUE & GROOVE
A method of joining individual planks of wood flooring to form a homogeneous unit by forming a cut from the edge of the block or strip to project outwards on one side and a groove in the opposite side to fit the tongue. 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 to mask an expansion gap.
A method of factory rapid-drying oil or lacquer that produces a harder wearing surface than air-dried finishes.
Volatile Organic Compounds (VOCs) comprise hundreds of natural and man-made, carbon-based agents. They react quickly with other carbon-based compounds, and evaporate easily, making them ideal solvents. VOCs can be found in cleaning products, disinfectants, pesticides, paints and other home decoration products. They are known to cause harm. Like formaldehydes, they cause irritation to eyes and airways, including asthma. But they also cause headaches, flu-like symptoms, can remain in the body and contribute, after prolonged exposure, to kidney and liver diseases and cancers.
VOCs also degrade the environment, polluting waterways and disposal systems and contributing to low-level atmospheric pollution, global warming and sick building syndrome.