Wall Construction And Nett Floor Surface

A wall has a footprint, and it takes away valuable space from your total house footprint. Some people never think about the amount of space being taken by walls, assuming that walls are paper-thin, or that the amount of space they take is negligible. But walls actually take quite a lot of space. Take a look at the floor plan below.

walls SHOB and SHON

This is a log house. The floor plan is 8×12 meters (outside dimensions) and we have drawn some random walls inside the house.

Outside walls are 45 cm:

  • 16 cm solid wood
  • 25 cm insulation material
  • 2 cm air gap
  • 2 cm larch on the outside.

U-value is 0,105 W/m2K. The total footprint of the house is 96 m2, but the nett usable floorspace is 76,41 m2, only 80% of the footprint. If we build this house as a panel house, we can reduce the thickness of the outside walls to 31 cm:

  • 1 cm gypsum
  • 1 cm OSB
  • 25 cm insulation material
  • 1 cm GYPROC
  • 2 cm air gap
  • 2 cm larch on the outside.

U-value is 0,122 W/m2K. We now have 81,50 m2 nett space, or 85%. That
is 5% an extra space. In France there are two abbreviations that you should know:

  • SHOB: Surface Hors Oeuvre Brute, and
  • SHON: Surface Hors Oeuvre Nette.