The threshold does most of the work
Soil arrives in an office block on footwear, on trolley wheels and on the air moving through a propped door. A well-specified transition zone intercepts most of it before it travels. That means adequate matting length, matting that is actually maintained rather than saturated, a hard floor immediately inside that can be wet mopped without damage, and a scheduled clean of the threshold itself rather than treating it as part of the general office round at the end of a shift.
Most sites under-invest here and then over-invest in carpet cleaning further inside. Extending entry matting and lifting its cleaning frequency is inexpensive, and it reduces the rate at which office floor coverings degrade. The plan should state the matting cycle explicitly, including how often mats are lifted so the floor beneath them is cleaned, because a mat sitting on trapped grit is doing the opposite of its intended job and will mark the surface it was installed to protect.
