Setting for opening, such assembly comprising a frame and method of attaching such a frame on a wall

The present invention relates to a frame (14) for opening intended to be fixed on a wall (12). The frame (14) comprises: • two vertical uprights (24) and two horizontal crosspieces (26), • means (28) for fixing the frame (14) on the wall (12), comprising at least one fixing lug ( 32) protruding from a portion (36) of a vertical upright (24) or horizontal crossbeam (26), the or each fixing lug (32) comprising a first folding portion (38) connected to said portion ( 36) via a first weakened fold area (40), and a second foldable portion (42) connected to the first folding portion (38) via a second weakened fold area (44), the first folding portion (38) having a length greater than the thickness of the wall (12), said portion (36) of vertical post (24) or horizontal crossbeam (26) comprising an oblong slot (50), said portion (36) and the first folding portion ( 38) being configured so that a non-zero distance separates the first folding portion (38) the lateral surface (23) of the wall (12) when the frame (14) is fixed to the wall (12).