A method of assembling a wall from prefabricated wall parts (2, 3), wherein - edge surfaces (7, 8) of two wall parts (2, 3) are placed against each other leaving a gap there between, and wherein - first and second sealing members are included in the gap to each act between said edge surfaces (7, 8) of the wall parts (2, 3), which sealing members extend in a longitudinal direction of said edge surfaces and are spaced apart in a transverse direction of said edge surfaces (7, 8) to define a cavity there between, wherein the method comprises the step of providing the first and second sealing members to the edge surfaces (7, 8) of the wall parts (2, 3) prior to assembly, whereby each of the sealing members includes a lip, the sealing member, including the lip, comprising or being made of a flexible material, the sealing member material, in particular having a hardness between 30-100 durometer hardness on a Shore A scale, preferably between 50-90 durometer, said lip comprising a base portion fixedly connected to one of the edge surfaces and a free edge portion, and wherein, upon placement of the edge surfaces against each other, the free edge of the lip of a sealing member is guided to curl inwardly relative to the cavity by a guide portion on the edge surface (7, 8) of the facing prefabricated wall part (2, 3), wherein - said cavity is filled with a solidifying liquid, such that the solidifying liquid acts on a cavity facing surface of each sealing member and presses the sealing member into engagement with at least one of the edge surfaces (7, 8), characterised in that the sealing member is comprised of a profile having a cross-section shaped as a U, V, L, C or J, such that said free edge of the lip is guided to curl inwardly relative to the cavity by the guide portion on the edge surface (7, 8) of the prefabricated wall part (2, 3). - edge surfaces (7, 8) of two wall parts (2, 3) are placed against each other leaving a gap there between, and wherein - first and second sealing members are included in the gap to each act between said edge surfaces (7, 8) of the wall parts (2, 3), which sealing members extend in a longitudinal direction of said edge surfaces and are spaced apart in a transverse direction of said edge surfaces (7, 8) to define a cavity there between, wherein the method comprises the step of providing the first and second sealing members to the edge surfaces (7, 8) of the wall parts (2, 3) prior to assembly, whereby each of the sealing members includes a lip, the sealing member, including the lip, comprising or being made of a flexible material, the sealing member material, in particular having a hardness between 30-100 durometer hardness on a Shore A scale, preferably between 50-90 durometer, said lip comprising a base portion fixedly connected to one of the edge surfaces and a free edge portion, and wherein, upon placement of the edge surfaces against each other, the free edge of the lip of a sealing member is guided to curl inwardly relative to the cavity by a guide portion on the edge surface (7, 8) of the facing prefabricated wall part (2, 3), wherein - said cavity is filled with a solidifying liquid, such that the solidifying liquid acts on a cavity facing surface of each sealing member and presses the sealing member into engagement with at least one of the edge surfaces (7, 8),