Fitting & Installation Technical Glossary

Wood Flooring Fitting and Installation Technical Terms Explained

Fitting & Installation Technical Glossary

Many people are unfamiliar with terms used in a particular industry, this blog is intended to help explain these phrases in a simple way, please let us know if you have any comments on these. There are a few blogs with separate headings on different aspects of wood flooring and fitting.


All solid wood flooring and Bamboo flooring should be placed in the room / environment where it is going to be fitted. In some cases where you have underfloor heating engineered wood flooring should also be acclimatised but can be fitted as soon as it is received if the conditions are normal. Every room or location has its own humidity levels and will depend on a lot of things. Acclimatisation means that wood flooring needs to get used to local humidity levels and heat. To acclimatise the boards correctly you should unpack them and allow the local air to circulate so that they can expand or contract and be stable prior to fitting. You should never acclimatise wood floors where there are still wet trades (wet trades means wet or damp plaster, damp concrete etc.)


These are the glues we use to fix the wood floor to the sub floor. Normally you would use the Bona R850 which we can supply along with a free notched trowel which can also be termed and applicator.


This is a wooden trim to match your floor that goes around the door trim. If you have an existing one our fitters can use a special saw to cut underneath this trim to give a newly fitted, polished finish.


This is a piece of wood normally 25mm x 50mm or larger that supports the hardwood flooring so that you can secret nail the floor. In most cases you should glue directly to concrete or joists but batten can be used to take account of different level so that when you floor is installed it is all on one level.


Our floor fitters can use contrasting materials such as white Oak and Walnut to create a border around the floor or in the middle.


This is a manmade board using small particles of wood as its main constituent. It is put in a high pressure press similar to the hot and cold press method used to make engineered flooring. Chipboard is one of the most common used subfloor as it is cheap but it is also very susceptible to damp. Leave it outside in the rain and it will disintegrate. Screws and normal nails will not work so if you use this as a sub floor you should glue the wood boards directly to this using Bona R850 adhesive. A better sub floor is bonded plywood.

Sandpaper Grit

Our floorboards are sanded to 120 grit and to put oil on the surface should be 120 grit to 180 grit. Grit is the coarseness of the sandpaper and 20 grit is very course with 180 grit being very smooth in comparison

Heart Wood

This is the hardest part of the tree and is normally darker than the outer rings of the tree and on a floor board will show as dark streak. With oils you can diminish this effect if you are trying to get a very uniform look.


These instruments measure the moisture content of the air. To do this accurately you need a good quality instrument and it must be left in the area to be tested for at least 24 to 48 hours. Moisture from the surrounding walls (especially if they have been recently plastered) and also the sub floor exchanges with the air and this rate of exchange will depend on the ambient conditions prevailing at the time of the test. So to get accurate readings the device needs to be left so that it can get an accurate average reading. When installing a wooden floor to ensure that there are no problems in the future the relative humidity should be between 55% to 60% and the moisture content of the subfloor no more than 8%.


This is often part of the subfloor but in old buildings you may not have this. If you have an old concrete floor always use BonaR410 or R580 to seal the top surface and keep any potential problem below not against the wood.


This is a structural beam that is used to support the upstairs floor or in old house the ground floor where there is a space under the ground floor with air bricks allowing air to circulate. The size of the joist will depend on when the house was built and also the loading it has to take. In old houses with air bricks the air circulated as we had open fires in these houses with central heating the floor boards will react more than they did in the old days which is why there are often large gaps as we like living in a hot house!

Latex Screed

You would use a latex screed if the concrete subfloor you were installing the wood floor on was uneven or unlevelled. These can sometimes be referred to as self-levelling compounds which is a liquid cement mix or where they add a paste or plastic to make the screed more flexible. These screeds can be anything for 3mm to 15mm thick and are normally quick drying. If you use such a levelling screed then we do not advise gluing the floor to this unless it is at least 12mm thick as it could lift from the original cement screed so please use these screeds with caution.

Damp Proof Membrane (DPM)

This is normally a plastic sheet that is impervious to water and moisture and is put below the cement screed before the cement is poured to stop any moisture going through the cement. It can get damaged so we also have a DPM on top of the cement such as Bona R410 or Bona R580 which are rubber type compounds that completely seal a floor to prevent any moisture from coming to the surface and gives you double protection. We always advise putting a DPM on top of a screed before fitting a floor because the last thing you want is for some moisture to creep through in a year and your nice wood floor lifts and warps and twists and does other nasty things that wood can do when subjected to too much moisture. In newer screeds the bottom of the screed will not have dried out anyway to the required level. The relative humidity in the screed needs to be less than 40% and the moisture content should be below 2%. If the wooden floor has a moisture content of 7% then the screed must be a lot lower than this.

Expansion and Expansion Gap

As wood is a hygroscopic material it will expand when it absorbs water or moisture and will also then contract when it loses it. However due to the cell structure and fibrous nature of wood once it expands it will never contract back to exactly the same size or shape which is why you can have cupped boards. When fitting a wooden floor even engineered you must always leave a gap around the perimeter at least 5mm for engineered boards and 10mm for solid wood. In the UK when we get humid weather the moisture content of wood flooring will be at its highest especially if doors and windows are left open, this means that the wood will absorb moisture and expand. In winter when we close all our doors and windows and turn up the central heating the humidity levels will be low so the wood will shrink, be careful not bring the humidity level below 20% otherwise you could cause serious damage to your wood floor even if you have engineered wood flooring. You should therefore air the house occasionally to maintain a natural environment.

Decibel Value and Sound Insulation

This is the measure of sound and our underlays have this in their specification. (Normally used in flats to prevent sound travelling to other apartments).

Face Nail and secret Nail: This is where you see the nail head on old floors that are in old buildings. Nails were normally punched below the surface and then filled and when they rust through you get dark patches on the surface of the floor. We now secret nail our boards thorough the tongue and groove but any solid board over 150mm wide should also have face nails otherwise with high humidity levels the boards could lift. This is why we only supply engineered boards wider than 150mm. BS8201:1987 states that boards exceeding 100mm in width should be fixed with surface nails we believe that secret screwing will be more than sufficient especially on our engineered boards up to 340mm wide.

Floating Floor

This is where the tongues and grooves are glued together using a PVA adhesive and the floor sits like a large slab on an underlay, so it 'floats' on top. This is not our preferred method of installation as it is always prone to problems. However with electric underfloor heating and some type of hot water system this is the only method that can be used Engineered boards can be floated but NEVER float a solid wood floor there be too movement.


This is normally a thin piece of wood that is used on top of joists when they are not level


This is a piece of timber that is fixed between joists so that it helps support the end of a board that spans the joists.

Floor sealer

This is a common term for varnish or lacquer to seal the surface this just sits on top of the wood.

Rising Damp

This happens when the membrane underneath a concrete screed or even in your foundations has failed and is cracked which will then allow moisture to rise up through the screed or walls. Moisture will always go to the driest part which is why we recommend adding a DPM on a screed even if it is perfectly dry and moisture free.


This is a concave shaped wood floor accessory that is used like beading not something we recommend as you should always fit you floor under skirting boards.


This is the concrete floor that is your subfloor


This is the movement of your natural wood floor that will change throughout the seasons depending on humidity levels and heating conditions.

Nailer or Porta Nailer

Professional floor fitters’ use these nail guns to ensure that the secret nails go through the tongue at the correct angle and correct pressure. They can be either electric or air pressure operated. They can be easily hired form most tool hire companies.

Natural Oil

This is a modern product used to finish floors, the latest are VOC free and use natural substances that are environmentally friendly. Having research the market extensively we use Timberex wood oils. These are the best finishes and you can easily repair and maintain an oiled board.

Penny Joints

These can be termed washer joints due to the fact that there are very small gaps left between each floor board or every few boards for additional expansion. The term penny or washer was used because they used a thin washer or penny as a guide to make sure that each gap was equal. Due to modern manufacturing techniques and also the tolerances and moisture content of our wood flooring there is no need to use these now.

Sub floor

This is what you will install your wood flooring on to and is the floor below your final flooring finish.

T Moulding

This is shaped like a T-section and is used when you have a wooden floor that needs a gap between doorway (no need with our engineered boards) and where you go from a wood floor to carpet.

Screw and Plug

This method is where you have very wide boards and to ensure that they will not warp or twist we drill a hole just larger than the screw head just below the surface and then screw the board direct to joists or batten. Once fixed the top of the hole is then plugged with the same wood and sanded down so that you would not notice the hole once the wood floor has been finished.

Wood Flooring Underlay

These are manufactured specifically for wood flooring do not use a carpet underlay as they are not the same and could cause problems later.

Skirting Board

These are the boards that go on the wall above the wood flooring to cover up the bottom of the wall and the expansion gap you need to leave around the edge of the room. We manufacture these in lengths of 2100mm and also have matching skirting boards for all our flooring.

UV Cured

This is a method used at our factory to cure the oils and lacquers that we apply. This method cures the finish quickly but also ensures a much harder longer lasting finish than if you applied lacquers on site. We only use this for our lacquered and UV oiled pre-finished flooring.


These are old fashioned floor finishes and although they give lustre to the floor they are also not as hard wearing as modern oil finishes and we do not recommend using them.

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