A semi-invisible combination of thermal insulating profiles of the lower part of sliding doors and windows which allows the unhindered passing of people and objects above it, comprising: a) at least one thermal insulating profile which is called frame and is adapted to be firmly attached to structural components of a building; b) at least one thermal insulating profile which is called sash which is equipped with an appropriate U-shaped channel in order to be able to receive a heat insulating panel or glazing ; and c) at least one tubular thermal insulating profile which is called added horizontal support ; wherein, in the mounted state, the added horizontal support and the sash connect via projections and cavities respectively after pressure is applied longitudinally at Π-shaped profiles (4a, 4b; 4c, 4d); wherein, in the mounted state, the said sash and an upper part of the said added horizontal support nave a visible part above the floor, wherein, in the mounted state, the said added horizontal support and the said sash slide in a movement groove of the frame , and wherein, in the mounted state, the said frame and a lower part of the said added horizontal support are below the floor, characterized in that the sash is made from PVC or strengthened Polyamide and the added horizontal support is made from Polyamide or Polyester, said Polyamide or Polyester incorporating or not fiberglass and being produced by pultrusion method. a) at least one thermal insulating profile which is called frame and is adapted to be firmly attached to structural components of a building; b) at least one thermal insulating profile which is called sash which is equipped with an appropriate U-shaped channel in order to be able to receive a heat insulating panel or glazing ; and c) at least one tubular thermal insulating profile which is called added horizontal support ; wherein, in the mounted state, the added horizontal support and the sash connect via projections and cavities respectively after pressure is applied longitudinally at Π-shaped profiles (4a, 4b; 4c, 4d); wherein, in the mounted state, the said sash and an upper part of the said added horizontal support nave a visible part above the floor, wherein, in the mounted state, the said added horizontal support and the said sash slide in a movement groove of the frame , and wherein, in the mounted state, the said frame and a lower part of the said added horizontal support are below the floor, characterized in that the sash is made from PVC or strengthened Polyamide and the added horizontal support is made from Polyamide or Polyester, said Polyamide or Polyester incorporating or not fiberglass and being produced by pultrusion method. wherein, in the mounted state, the added horizontal support and the sash connect via projections and cavities respectively after pressure is applied longitudinally at Π-shaped profiles (4a, 4b; 4c, 4d); wherein, in the mounted state, the said sash and an upper part of the said added horizontal support nave a visible part above the floor, wherein, in the mounted state, the said added horizontal support and the said sash slide in a movement groove of the frame , and wherein, in the mounted state, the said frame and a lower part of the said added horizontal support are below the floor, characterized in that the sash is made from PVC or strengthened Polyamide and the added horizontal support is made from Polyamide or Polyester, said Polyamide or Polyester incorporating or not fiberglass and being produced by pultrusion method. <EOS>