Underlayment tile for an assembly of an underlayment by interconnecting a plurality of such underlayment tiles, wherein the underlayment tile comprises a tile body including: - a bottom side for placing the tile body on a surface, in which the bottom side defines a planar plane for placement of the tile body on the surface; - a top side which is arranged to support an upper layer and which top side comprises at least one channel portion for receiving a heating conduit, such that the underlayment is suitable to be used as a floor heating underlayment; and - an outer circumferential side wall which includes at least a first side wall (40.1) and a second side wall (40.2) which second side wall (40.2) is positioned opposite the first side wall (40.1), wherein the tile body comprises at least one pair of a complementary shaped first and second coupling member (41,42), in which the first coupling member is positioned at the first side wall (40.1) and in which the second coupling member is positioned at the second side wall (40.2), such that two adjacently positioned underlayment tiles are interconnectable by a pair of a respective first and second coupling member of each underlayment tile, characterised in that the first coupling member is formed as a male member which comprises a protrusion which protrudes in a longitudinal direction, and in that the second coupling member is formed as a female member which comprises a recess which is configured to receive the protrusion, wherein the recess comprises two opposite recess walls (420L,420R) for enclosing the protrusion in between the recess walls (420L,420R), such that in an assembled condition of two underlayment tiles the first and second coupling member (41,42) block a relative movement of the underlayment tiles in parallel with the planar plane in a direction traverse to the longitudinal direction, wherein the first and second coupling member (41,42) permit a relative movement over a travel distance of two interconnected underlayment tiles in the longitudinal direction, wherein a stopper (412, 422B) is provided for limiting the travel distance in between the two interconnected underlayment tiles, such that the two interconnected underlayment tiles are movable from a compact to an extended configuration. - a bottom side for placing the tile body on a surface, in which the bottom side defines a planar plane for placement of the tile body on the surface; - a top side which is arranged to support an upper layer and which top side comprises at least one channel portion for receiving a heating conduit, such that the underlayment is suitable to be used as a floor heating underlayment; and - an outer circumferential side wall which includes at least a first side wall (40.1) and a second side wall (40.2) which second side wall (40.2) is positioned opposite the first side wall (40.1), wherein the tile body comprises at least one pair of a complementary shaped first and second coupling member (41,42), in which the first coupling member is positioned at the first side wall (40.1) and in which the second coupling member is positioned at the second side wall (40.2), such that two adjacently positioned underlayment tiles are interconnectable by a pair of a respective first and second coupling member of each underlayment tile, characterised in that the first coupling member is formed as a male member which comprises a protrusion which protrudes in a longitudinal direction, and in that the second coupling member is formed as a female member which comprises a recess which is configured to receive the protrusion, wherein the recess comprises two opposite recess walls (420L,420R) for enclosing the protrusion in between the recess walls (420L,420R), such that in an assembled condition of two underlayment tiles the first and second coupling member (41,42) block a relative movement of the underlayment tiles in parallel with the planar plane in a direction traverse to the longitudinal direction, wherein the first and second coupling member (41,42) permit a relative movement over a travel distance of two interconnected underlayment tiles in the longitudinal direction, wherein a stopper (412, 422B) is provided for limiting the travel distance in between the two interconnected underlayment tiles, such that the two interconnected underlayment tiles are movable from a compact to an extended configuration.