FIELD: construction engineering; polyvinyl chloride sections, mainly for guarding openings of buildings and structures. SUBSTANCE: set of sections includes at least one leaf-forming section and at least one section of T-shaped impost that has flange and upright. Mentioned sections are made of PVC base material. Some parts of side walls of upright are relatively parallel at certain length and are tilted to each other at point where they are abutting against flange. Upright is divided by means of partitions parallel to flange into compartments. One of partitions is designed for accommodating reinforcing section and has bosses protruding inside compartment. Flange is divided by partitions parallel to longitudinal axis of upright into central and peripheral compartments. Central compartment of flange is non-partitioned structure separated from upright by partition; the latter is displaced relative to remaining partitions through distance not shorter than partition thickness. Sides of central compartment are closed by partitions adjacent to those of peripheral compartments arranged beyond mating points of tilted parts of upright. Side walls are spaced apart through distance exceeding upright width between its external surfaces at location of reinforcing section. Slots may be made on external surface of impost-forming upright concealed upon mounting the window blocks over its length for locating fastening members, mainly, tapping screw heads at reinforcing section and/or fittings. Leaf-forming section may have at least one compartment provided with boss made in a spaced relation to opposing wall of compartment; boss is perpendicular to fastening member axis and spaced from external surface of leaf over mentioned axis through length not exceeding that of mention fastening member. Set of sections may be provided with specifically packed draft fillet placed in mentioned slots; at least one external surface of draft fillet is arranged within external surface of section contacting it. Set may incorporate window frame forming section that has central compartment to receive reinforcing section; parallel partitions of compartment and external walls of section form non-partitioned compartments; one of the latter has bosses engageable during installation with fastening members; made on external surface of section concealed upon mounting window blocks over its length are slots for locating fastening members, mainly tapping screw heads, at reinforcing sections and/or fittings. EFFECT: improved heat insulation due to reduced heat loss; improved reliability and endurance of set due to better quality of assembly. 5 cl, 6 dwg
