You are currently viewing


Soil filtration lines (or draught marks as they are sometimes known) are dark soiled areas that develop gradually on a carpet; they are most commonly found around the edges of a room next to the wall.

These marks are the result of dust particles carried in the air moving through wall cavities and beneath gaps in poorly fitted floorboards, or between the floorboards and skirtings, leaving dust deposited on the carpet pile much like a filter action. Sometimes the lines can show quite clearly the shape of the floorboards beneath.

These marks can be fairly stubborn and will require special attention when cleaning to ensure a satisfactory result but, even then, they cannot always be eradicated completely. The degree of removal depends on the amount and type of soil, length of time the soil has accumulated, amount of airflow, colour of carpet and type of fibre. The lines can be removed most easily from synthetic fibres. However, in severe cases, especially on light coloured carpets, traces may still remain after cleaning.

As soil filtration lines sometimes cannot be completely removed it is always best to avoid them occurring in the first place. If any of the subfloors (beneath the carpet and underlay) consist of poorly fitted and gappy floorboards there will be a likelihood of dust migration.

Unfortunately some carpet fitters do not impart this information either prior to, or at the point of, installation. So, if you have badly fitted floorboards, we would advise that remedial work to seal draughts is carried out before any new carpet is fitted. This is even more important when light coloured carpet is chosen as the signs of soil filtration can become apparent very quickly and, as mentioned previously, more difficult to remove.

A good quality underlay should always be fitted and any gaps within the floorboards should be filled with a suitable flexible sealant or, alternatively, by covering the existing subfloor with plywood. You can either do this yourself (if you feel confident enough) or ask their fitter to do it for you. It is worth noting that many fitters will be able to provide this service prior to installation of the carpet and underlay for very little extra cost.

How to minimise filtration soiling

  • Prevent the airflow through carpet and carpet edges by sealing openings through the carpet and under doors and skirting.
  • Keeping the air in the house clean and using good quality vacuum cleaner can help.
  • Professional cleaning – every 12 months is recommended.
  • Filtration soils may require special cleaning treatment for effective removal. Unlike Carpetcare, other carpet cleaning companies don’t clean carpets right up to the skirtings, leaving dirt and microbes from the air resting in your carpet pile until the next time the air pressure in the room changes and this dust is blown back into the room.
  • You can be assured of a quality carpet cleaning service from Carprtcare North East. We certainly do clean right up to the skirting and most of the time can also remove those nasty filtration marks.