Friction Surface means an interior or exterior surface that is subject to abrasion or friction, including, but not limited to, certain window, floor, and stair surfaces. Friction surfaces must be addressed when performing interm controls and standard treatments.

24 CFR 35.1330 (c) Friction and impact surfaces.
  (1) Friction surfaces are required to be treated only if:
  (i) Lead dust levels on the nearest horizontal surface underneath the friction surface (e.g., the window sill, window trough, or floor) are equal to or greater than the standards specified in 35.1320(b);
  (ii) There is evidence that the paint surface is subject to abrasion; and
  (iii) Lead-based paint is known or presumed to be present on the friction surface.
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  (3) Examples of building components that may contain friction or impact surfaces include the following:
  (i) Window systems;
  (ii) Doors;
  (iii) Stair treads and risers;
  (iv) Baseboards;
  (v) Drawers and cabinets; and
  (vi) Porches, decks, interior floors, and any other painted surfaces that are abraded, rubbed, or impacted.
  (4) Interim control treatments for friction surfaces shall eliminate friction points or treat the friction surface so that paint is not subject to abrasion. Examples of acceptable treatments include rehanging and/or planing doors so that the door does not rub against the door frame, and installing window channel guides that reduce or eliminate abrasion of painted surfaces. Paint on stair treads and floors shall be protected with a durable cover or coating that will prevent abrasion of the painted surfaces. Examples of acceptable materials include carpeting, tile, and sheet flooring.
 (5) Interim control treatments for impact surfaces shall protect the paint from impact. Examples of acceptable treatments include treatments that eliminate impact with the paint surface, such as a door stop to prevent a door from striking a wall or baseboard.
 (6) Interim control for impact or friction surfaces does not include covering such a surface with a coating or other treatment, such as painting over the surface, that does not protect lead-based paint from impact or abrasion.