A levelling system for laying tiles or floor elements in a desired plane XY, comprising: - a base extending in a plane A, - a stem extending from the base in a longitudinal direction Z and fixed to said base by means of at least one pre-weakened zone, configured to allow separating the stem from the base, the stem comprising at least one first engagement member; - a pressure member comprising a tubular body defining an inner slot configured to slide over the stem in the longitudinal direction Z, the slot defining guiding means mating with the stem, thereby preventing rotation of the pressure member around the stem, the pressure member comprising a pressure surface extending in a plane parallel to the XY plane and facing the base when the pressure member is positioned over the stem; - a pressure adjustment member comprising a tubular body having at least one inwardly directed second engagement member configured to engage with the first engagement member, wherein one of said first or second engagement members (9, 12) comprises at least one barb and the other engagement member comprises a thread configured to engage with the barb; wherein the barb or barbs are flexible allowing movement of the pressure adjustment member over the stem in a direction to the pre-weakened point without or with limited rotation of the pressure adjustment member; characterised in that said first engagement member comprises said at least one barb and in that said second engagement member comprises said thread configured to engage with said at least one barb; wherein said first engagement member comprises a series of superposed barbs slantingly extending from the stem in a direction of said plane A, said barbs defining free end portions; and said second engagement member comprises said thread configured to engage with free end portions of the series of superposed barbs, allowing adjustment of the position of the pressure member in said longitudinal direction Z. - a base extending in a plane A, - a stem extending from the base in a longitudinal direction Z and fixed to said base by means of at least one pre-weakened zone, configured to allow separating the stem from the base, the stem comprising at least one first engagement member; - a pressure member comprising a tubular body defining an inner slot configured to slide over the stem in the longitudinal direction Z, the slot defining guiding means mating with the stem, thereby preventing rotation of the pressure member around the stem, the pressure member comprising a pressure surface extending in a plane parallel to the XY plane and facing the base when the pressure member is positioned over the stem; - a pressure adjustment member comprising a tubular body having at least one inwardly directed second engagement member configured to engage with the first engagement member, wherein one of said first or second engagement members (9, 12) comprises at least one barb and the other engagement member comprises a thread configured to engage with the barb; wherein the barb or barbs are flexible allowing movement of the pressure adjustment member over the stem in a direction to the pre-weakened point without or with limited rotation of the pressure adjustment member; characterised in that said first engagement member comprises said at least one barb and in that said second engagement member comprises said thread configured to engage with said at least one barb; wherein said first engagement member comprises a series of superposed barbs slantingly extending from the stem in a direction of said plane A, said barbs defining free end portions; and said second engagement member comprises said thread configured to engage with free end portions of the series of superposed barbs, allowing adjustment of the position of the pressure member in said longitudinal direction Z.