False wall device for covering a wall of the wall or ceiling type, comprising: - a chassis forming a frame whose shape matches that of the wall; - a stretched canvas hung on the chassis so as to cover the wall, characterised in that it comprises: - means for dismantling and reassembling at least one removable peripheral section of the canvas in order to have access to the wall, said means for dismantling and reassembling consisting of a removable attachment device provided between at least one removable peripheral section of the canvas and the chassis, said removable attachment device consisting of an attachment edge fixed to said removable peripheral section of the canvas and capable of being inserted inside a groove provided for this purpose in the chassis; - means for adjusting the canvas with respect to the frame located on the periphery of the canvas except for said removable peripheral section, said adjustment means consisting of i) a profile (9, 9') capable of fitting removably into a groove provided for this purpose in the chassis and in excess material provided on the periphery of the canvas apart from the said removable peripheral section, this excess material being devoid of attachment means and capable of being fixed in said profile and then cut off. or i) a flexible clip capable of fitting removably into a groove provided for this purpose in the chassis and in excess material provided on the periphery of the canvas apart from the said removable peripheral section, this excess material being devoid of attachment means and capable of being fixed in said clip and then cut off. - a chassis forming a frame whose shape matches that of the wall; - a stretched canvas hung on the chassis so as to cover the wall, - means for dismantling and reassembling at least one removable peripheral section of the canvas in order to have access to the wall, said means for dismantling and reassembling consisting of a removable attachment device provided between at least one removable peripheral section of the canvas and the chassis, said removable attachment device consisting of an attachment edge fixed to said removable peripheral section of the canvas and capable of being inserted inside a groove provided for this purpose in the chassis; - means for adjusting the canvas with respect to the frame located on the periphery of the canvas except for said removable peripheral section, said adjustment means consisting of i) a profile (9, 9') capable of fitting removably into a groove provided for this purpose in the chassis and in excess material provided on the periphery of the canvas apart from the said removable peripheral section, this excess material being devoid of attachment means and capable of being fixed in said profile and then cut off. or i) a flexible clip capable of fitting removably into a groove provided for this purpose in the chassis and in excess material provided on the periphery of the canvas apart from the said removable peripheral section, this excess material being devoid of attachment means and capable of being fixed in said clip and then cut off. i) a profile (9, 9') capable of fitting removably into a groove provided for this purpose in the chassis and in excess material provided on the periphery of the canvas apart from the said removable peripheral section, this excess material being devoid of attachment means and capable of being fixed in said profile and then cut off. or i) a flexible clip capable of fitting removably into a groove provided for this purpose in the chassis and in excess material provided on the periphery of the canvas apart from the said removable peripheral section, this excess material being devoid of attachment means and capable of being fixed in said clip and then cut off.