The array of symbols that accompanies most carpet tiles is intended to help the buyer make an informed choice. It's a well-intentioned aim, but unless they're fully understood they can mislead rather than guide. Is a tile fire-resistant? The presence of a fire-resistance symbol would suggest so, but in fact it simply shows that the carpet tile has been tested it's the text below the symbol that actually tells you how it would behave in a fire.

In this article I'll try to clarify the most important symbols, and so help a buyer to choose wisely. There's also more information on the tests themselves in my article on http://www.burofloor.com/symbols-article-32.

Wear Resistance

For carpet tiles for commercial premises, this is where the story usually starts. Tiles in these areas are subject to far harder service than those in the home. Castor chairs, coffee spills, copier toner and indifferently wiped feet all take a huge toll. For this reason you should be looking for contract or, ideally, heavy contract tiles. The symbol for project-suitable tiles shows a stylised office block on the left, with a varying number of human figures on the right the more figures, the tougher the carpet. Put simply, if you see a house on the left, it won't do the job - however many figures you see on the right.

Castor Chairs

Castor chairs are a fact of office life. But they dig their way through floor coverings faster than Charles Bronson leaving Stalag Luft III (though admittedly they rarely dispose of the debris on the football field no simile is perfect). There's a standard castor test to classify a carpet tile's resistance to this sort of wear, the symbol for which is, unsurprisingly, a castor.

But domestic tiles can be tested for castor resistance and be passed as suitable for occasional use. Confusingly, the commercial symbol doesn't carry an office image, so the absence of a house symbol is the visual check to make sure you're not misled.

It's worth noting here that polypropylene carpet tiles can pass the castor chair test in terms of wear-through, but may still be unsatisfactory in use. This is because polypropylene pile tends to flatten permanently under compression, giving a whitish effect in heavy wear areas. Nylon pile tends to be more resistant to this flattening.

Fire Resistance

Health and safety requirements put this factor right at the top of the list, alongside wear resistance. This is a tricky, specialised area, needing an understanding of the various ISO specifications. Essentially though it's important to understand that the presence of a fire resistance symbol isn't a guarantee of non-combustibility.

Making it all as simple as possible, the fire classification falls into groups from A to F, with A being the most fire-resistant. In fact the highest rating achievable by a carpet tile is "B".

The main classifications are subdivided A1, A2 etc, and there's also an "s"suffix to identify a product's smoke emission properties:

For the sake of completeness I'll also mention the cigarette-resistant symbol. Now that smoking is prohibited in public areas, this is far less important than used to be the case, and is rarely seen.

Fire resistance is a complex subject and so has to be an area for expert advice, particularly in escape routes.

Electrical Behaviour

Those tiny electric shocks when you touch the radiator or the photocopier might not be dangerous, but they're pretty damned irritating. And leaping in the air, flapping your hand and screaming obscenities almost never enhances your presentation of this year's sales forecasts.

But while the staff spill coffee and endure the non-sympathy of their co-workers, computers quietly eat all your data and expire to their silicon afterlife. Static electricity isn't welcome in the office.

For most applications all you need to look for is the anti-static symbol. This tells you that the carpet tile has permanent anti-static characteristics, so you shouldn't feel electric shocks. This level of protection meets IBM's and ICL's standards, so it's quite adequate for most offices.

Where particularly delicate electronic equipment is in use, a more conductive carpet tile is required. Static electricity builds up because the charge created by friction can't earth itself through the carpet. By making a carpet tile more conductive it's possible to discharge this build-up. At first glance, the following two symbols are identical:

The Devil's in the detail here - 109 or 106 Ohms. In the former case, the tile dissipates the static build-up, while in the latter it actually conducts it through to the floor below.

Sound Absorption

Open plan offices can be very noisy places. This can make using the phone, conversing or just concentrating a real challenge. We can reduce the noise burden with acoustic screens, but choosing a sound-deadening carpet tile will help tackle the problem, literally, at base.

There are two types of acoustical symbol: one that guides you on how much ambient noise is absorbed by the tile, and one that shows how much noise is passed through to the floor below. In modern offices with concrete floors the latter of these is rarely a major problem. It's only in older buildings with wooden floors you usually need to worry too much about noise transmission.

The symbol above tells you that the floor covering has good sound absorption characteristics, making it suitable for open-plan offices.

This symbol indicates that the carpet tile provides good sound insulation through the floor.

Comfort Class

This measurement is less relevant to commercial carpet tiles than to domestic. It's based on pile weight, and gives an idea of the "luxury level" of the carpet. Very heavy pile isn't usually desirable in offices, shops or other such premises as it can be prone to flattening. But too thin a pile gives a cheap, unyielding impression. In general, carpet tiles are designed with medium pile weight in order to give a good balance of wear and luxury. three to four "tufts" on the symbol indicate an excellent quality tile.

Laying Instructions

In addition to wear and suitability indicators, some carpet tiles also carry laying guidance. Most commonly, tiles are laid at right-angles to one another, giving a pleasing chequerboard effect. This has the benefit of disguising any variation in colour between tiles. Some tiles , usually more expensive, can also be laid parallel. This is often called "broadloom laying" as it hides the joins between tiles, giving a luxurious broadloom effect. It's thus possible to achieve a wall-to-wall carpet effect without losing the benefits of flexibility and hard wear associated with carpet tiles.

This doesn't pretend to be an exhaustive explanation of carpet symbols; there are many, many more. What should be clear is that the symbols give you only a broad guide to a carpet tile's suitability. I'd recommend using them to make a preliminary selection, and then talk to a trustworthy, knowledgeable supplier to make sure you make the right ultimate choice.