How the Height of Floors Relate to the Height of the Terrain

Reference Number: KB-00861
Last Modified: August 17, 2021

The information in this article applies to:

Home Designer Professional or Home Designer Architectural or HomeDesigner Suite



QUESTION

How does the height of the terrain relate to the height of my floors?


ANSWER

In the real world, floor platforms are nearly always built so that you step up into a building. There are a number of reasons for this, but perhaps the most important is to prevent the structure's framing from coming into contact with the terrain. Over time, exposure to moisture in the soil can damage or even ruin untreated lumber in a framed floor platform or wall. For this reason, building codes in most areas require that floors be raised off the terrain.

Home Designer programs raise the building pad off the terrain for you automatically. The amount that the building pad is raised depends on the type of foundation you have built in your plan:

  • No foundation - The distance between the Default Floor Height of 0" and the terrain is equal to the depth of the default floor structure thickness for Floor 1.

    Section view displaying a structure and a terrain without a foundation

  • Walls with Footings - The distance between the Default Floor Height of 0" and the terrain is equal to the depth of the default floor structure thickness for Floor 1, plus the default Sill Plate Height of the foundation, plus 6" (187 mm).

    Section view displaying walls with footings with the terrain 6" below the top of the footing

  • Grade Beams on Piers* - Similar to the Walls with Footings option listed above. The distance between the Default Floor Height of 0" and the terrain is equal to the depth of the default floor structure thickness for Floor 1, plus the default Sill Plate Height of the foundation, plus 6" (187 mm).
    *Home Designer Pro Only
  • Monolithic Slab - The Default Floor Height of 0" is raised 8" (200  mm) above the terrain.

    Terrain is 8" below the top of the slab
Note: The distances described above may vary somewhat in older program versions. Also, to make sure the automatic terrain height is up to date with the foundation type, select Terrain> Build Terrain.


To specify a different distance between the floor and terrain

  1. Using the Select Objects  tool, select the Terrain Perimeter, then click the Open Object edit button.

    In Home Designer Pro, you can also navigate to Terrain> Terrain Specification from the menu.


  2. On the General panel of the Terrain Specification dialog, remove the check from the Automatic box, then type in the needed value in the Subfloor Height Above Terrain field. 

    Uncheck the Automatic box to change the Subfloor Height Above Terrain value


  3. Click OK to apply the change.
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