English Timbers

Solid Hardwood flooring

An Explanation of Terms

Adhesives - Normally used for bonding timber floors or softwood battens to the sub-floor. We recommend Proflex MS adhesive which is both water and solvent free and very safe to use..

Applicator - A synthetic lambs wool roller or pad fixed to a holder. Used for spreading the floor lacquer to give an even coating.

BS 8201 - The British Code of Practice outlining the guidelines for laying wood floors. Not particularly detailed.

Building paper- A vapour barrier which can be used under the hardwood floor.  It consists of a reinforced bitumen layer between 2 outer layers of paper and we recommend Sisakraft 420 or 728, or Novia A1F paper. Building paper is slightly permeable, self sealing around nails and is preferable to polythene in some situations.

Burrs - Clusters of small knots producing a cats paw-like pattern in the wood.

Checks & Shakes - Small, non-structural surface cracks - usually occur during air drying, otherwise inherent in the wood. Found occasionally in the lower grades & easily filled.

Chipboard - Any reference to chipboard is to the T & G moisture resistant variety.

DPM - Damp Proof Membrane - An impervious vapour barrier which is used under the new floor to isolate it from the sub floor. There are different options depending on the type and condition of subfloor.  The main three types are a polythene sheet, an epoxy resin surface coating and a building paper.  

Ends Matched - A tongue and groove machined on the ends of the board which allows the floor to join between supports which minimises waste & allows quicker installation.

Equilibrium Moisture Content (EMC) - This is the moisture content that a material eventually achieves in a stable atmosphere where both temperature and relative humidity are constant. Different materials may have different EMC's in the same conditions.

Expansion Gap - A gap left around the perimeter of the floor to permit the flooring to expand. Occasionally small gaps are introduced within a large floor area for the same purpose. Floors mostly expand and contract across the width of the board. Movement along the length of the board is minimal

Filler - A filling medium which may be applied to the wood before final sanding to fill any slight defects in the lower grades. Normally a resin mixed with sanding dust and other colours.

Finger Jointing - This is a glued mechanical like a series of interlocking fingers which is used to join the ends of timber together. Long pieces of timber can be produced from shorter lengths. The finger joint is not seen on the surface of the board, only on the side.

Floating floor - A sub floor which is not rigidly fixed to its own sub-floor, normally chipboard laid over polystyrene insulation. Generally not suitable as a sub floor for fixing solid wood floors.

Grading - A means of separating out batches of the same timber with similar characteristics. English Timbers flooring is accurately controlled within fine limits and orders placed some time apart will be essentially the same.

Hardwood - Timber from deciduous trees. The term is not a description of the actual hardness of the timber, in fact there are softwoods which are very hard Eg. Yew wood, and hardwoods which are very soft Eg. Balsa wood.

Heat Treated - This is a process which is used to change the colour of the timber and darken it. Different methods are used and the properties of the finished timber vary a little.

Kiln Drying - A process by which the moisture content of the timber is reduced to ensure stability in heated environments. English Timbers unfinished flooring normally has an average moisture content of about 9%, but batches vary a little.

Knots - Round or oval features caused by twigs or branches growing out of the main trunk. They are usually darker than the surrounding timber & invariably crack when kiln dried because of differential shrinkage. Normally filled before sealing the floor.

Moisture Content - A measure of the amount of residual moisture remaining in the timber. A 10% moisture content means that the timber contains 10% water by weight combined within the structure of the timber. Moisture content is determined by moisture meters and oven testing. The moisture content will change in sympathy with the ambient temperature and relative humidity.

Moisture Meter - A device to measure the moisture content of the timber. The most common method measures the current between 2 pins pushed into the timber and is calibrated according to the resistance or conductivity of the wood.
The second method measures the changes in an electromagnetic field generated in the wood and is calibrated according to wood density.
Neither method is particularly accurate because of the inherent variation in the resistance & density of different trees etc.  For maximum accuracy, use a top quality meter with species calibration, a hammer probe and temperature adjustment and take the average of many readings.

Movement - The natural expansion & contraction of the flooring during service caused by the changes in seasonal temperature and humidity. Floors expand in summer and contract during winter when the heating is running. Movement outside these seasonal variations is usually caused by damp within or entering the structure, or by excessive temperatures combined with low humidities

Nails - Serrated T nails 50mm long for maximum grip. Requirements:- approx. 45 per square metre for 90mm strip, 40 per square metre for 100mm strip and 30 per square metre for 128mm wide. The more nails per square metre, within reason, the better the fixing.

Pneumatic Floor Nailer - Air operated nailer permitting nailing at 45 degrees and using ribbed nails. Very fast to use and does not cramp the floor. Minimises the need for intermediate expansion allowance. Best used in conjunction with a powernailer for maximum efficiency.

Powernailer - A hand operated floor nailer used for laying hardwood strip floors. The 45R drives a serrated nail through the base of the tongue at 45º without the need for pre-drilling and the 101R is a face nailer. In both cases the machines incorporate a ratchet and are multi-blow for ease of use. Powernailers cramp the floor together as they drive the nail.

Relative Humidity (RH) - A measure of the amount of water vapour within the atmosphere. 100% RH indicates that the air is saturated and cannot absorb any further water in vapour form. 0% RH indicates a totally dry atmosphere and no water vapour in the air. The amount of water vapour which the air can hold is also dependent on the temperature and it is normal to quote the RH in conjunction with the temperature. Eg. 75% at 20ºC. Air can hold more vapour as the temperature increases. So, if the RH was 100% at 20ºC and the temperature dropped, some of the air would condense as water droplets.

Sapwood - The outer part of the tree. The timber is usually cream/white in colour. In maple and ash the highest grade timber is the white sapwood. In walnut and oak the highest grade is free from sap.

Sealer or lacquer - The surface coating which is applied to the floor to enhance the grain and protect the timber. Usually water based. A primer coat may be applied in certain circumstances if appropriate - Refer to the Finishing Section.

Secret Nailing - A method of fixing the floor by driving a nail at 45º through the top of the tongue and into the sub floor. This is best done with a Powernailer or pneumatic nailer.

Shrinkage - The contraction of the timber during seasoning.

Softwood Battens - Pressure treated lengths of softwood usually 44mm wide and in various thicknesses. Used as an intermediate sub-floor over concrete. Must be kiln dried. Best option is protim or solvent based treatment after drying. Should not be tanalised after drying.

Solid - All English Timbers Solid flooring is machined from 100% solid hardwood & contains no veneers, laminates or man made boards.

Stains - A solution applied to the floor before the sealer to change the colour.

Strip Floors - A solid hardwood floor is made up of individually laid pieces of timber which are tongued and grooved to the sides and ends. Thickness is usually 20mm. Lengths are random up to 1500mm. Sanded and sealed in situ. Our Wide Strip Floors are normally 128mm wide.

Sub-floor - The part of the floor structure to which the hardwood floor is fixed. May be concrete, plywood, chipboard etc. The integrity of the finished hardwood floor is only as good as the sub floor.

Tongue & Groove - an accurately machined male & female profile along the edge of each board to interlock adjacent boards together.

Under Floor Heating - A method of heating a building whereby the heat is transmitted through the floor to warm the air in the room. Various methods are available. It is important that the system is carefully designed so that the floor is not damaged and the absolute minimum of heat is transmitted.

Revised 07/01/08

Back to the top