A shoe moulding is a wooden moulding, usually a quarter-round, which is incorporated into the base moulding in the interiors of homes or offices in the traditional style. The shoe moulding is used when the base moulding, oftentimes large, rectangular in section, and inflexible, comes in contact with a hard floor surface, such as wood, linoleum, or vinyl flooring. The line of the flooring may not be totally level throughout, and this waviness becomes obvious when viewed against the base moulding – the gap between the floor and the base may vary widely. The flexible shoe moulding easily contours itself to the variations of the floor at the base, effectively hiding the shittiness of today's methods of construction.

Modern interiors substitute the base moulding with a shadow gap, or a consistent reveal where the wall finish stops short of the floor, leaving a gap that varies from a consistent half an inch to perhaps four inches (where a mechanical grille may be hidden. The problem with the shadow gap is that it demands the utmost care in it's construction – should the floor be too wavy at the wall, the shadow gap will not appear »clean«. Such extra care will cost extra money, a luxury as things go in America. So the architect satisfices with the use of the shoe moulding, an additive solution. Good design is always reductive. The shoe moulding, therefore, is a symbol of an architect's surrender.