Process for installation of insulation and corresponding set of installation accessories material.

The invention relates to a method of laying on rafters or under rafters, a flexible insulating material (3) in roll form, characterized in that, at each junction (7) between two successive widths of insulating material: a spacer is arranged (8) facing said junction between two consecutive framework elements, the spacer being arranged so as to have a face (17) extending substantially in the laying plane and offering support in this plane to the two widths of material insulation; assembling the spacer to the two structural members by means of two connecting pieces (9) each comprising a flange (11) strut support and a flange (10) of fixation, by coupling each axial end of the spacer to the spacer support frame of a connecting piece and fastened the fastening web of said connecting piece at one of the structural members.