Why does the floor get discolored underneath a floor mat?

Yellow, Brown & Discoloring of Floor Tiles Under Floor Mats

From time to time customers complain that mats cause the floors beneath them to discolor. This complaint has applied both to carpet and hard surface floors such as vinyl or tile. The discoloration is usually a yellow or brown color.

The most likely cause for this is moisture. There are several potential ways that moisture can cause discoloration:

  • Moisture from the ground comes up through the floor until it reaches the floor surface. This moisture normally evaporates and goes unnoticed. Placement of a mat on the floor prevents the evaporation, therefore trapping the moisture, thus causing the discoloration. This seems to be most common at entrances where cold or warm air enters buildings when the door is opened causing condensation (sweating).
  • Placement of mats on freshly cleaned and still damp carpet. This prevents carpet from fully drying, thereby causing discoloration.
  • Moisture from the back of mats. If not properly dried, the back of mats can be damp, thereby providing moisture to cause discoloration.
  • There can be a reaction between chemicals in the rubber backing and the floors or floor finishes used on hard surface floors.
  • Lack of exposure to sunlight. It is common to see floors change color when they are covered by counters, file cabinets, etc. This is caused by both lack of exposure to sunlight and restricted airflow.

In most instances where mats are placed and floor discoloration results, the customer is faced with a difficult decision. Use no mat and the floor doesn't discolor, however, the floor is damaged by tracked in soils, moisture and dirt, and the entire area deteriorates. Or use a mat and protect the floor with resulting discoloration in the area underneath the mat. Of the two, most customers select the latter.

Preventing Discolorization of Tiles & Flooring

Completely Dry Both Surfaces After Cleaning

Completely Dry Both Surfaces After Wet Cleaning

There will be residual moisture on both surfaces in the event that a Steam Vacuum, Box Extractor or Floor Burnisher has been used to clean the floor, carpet or floor mat.

Once the floor, carpet and floor mat(s) are completely dry, place the mats in their correct spot. As with all entrances and heavy foot traffic areas, moisture will be tracked in from the outside. A strict cleaning schedule is suggested to not only preserve the underlying floor, but the lifetime of the floor mat itself.


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