Abstract. Polymers in confined spaces lose conformational entropy. This induces a net repulsive entropic force on the walls of the confining space. A model for this phenomenon is a lattice walk between confining walls, and in this paper a model of an adsorbing partially directed walk is used. The walk is placed in a half square lattice L 2 + with boundary ∂L 2 + , and confined between two vertical parallel walls, which are vertical lines in the lattice, a distance w apart. The free energy of the walk is determined, as a function of w , for walks with endpoints in the confining walls and adsorbing in ∂L 2 + . This gives the entropic force on the confining walls as a function of w . It is shown that there are zero force points in this model and the locations of these points are determined, in some cases exactly, and in other cases asymptotically.