we are planning on building a house, and i had a question about the exterior walls. does the second floor exterior wall have to run on top of the first floor exterior wall? we are trying to make the second floor a few feet shorter on 2 sides of the house to save unnecessary sqftage.. is this possible? if so is it cost effective?


  • There's no reason why it can't be done; it'll just look a bit odd depending on how it's done. Of course, the joists on the top of the first floor will have to bear the weight of the second floor, instead of that weight being directed straight into the first floor's walls.
    – BillDOe
    May 15 '18 at 22:30
  • 1
    You may want to arrange things so the extra space is all one one side - e.g., 12' x 6' rectangle instead of 2 sections of 12' x 3' at right angles - that way you would have the option of putting a door in the wall and add a railing for safety and have a 2nd floor outdoor area to use when the weather is nice. May 15 '18 at 22:40

I’m not sure what you are saving: 1) Roofing and roof structure? 2) Walls? 3) Second floor structure? 4) Foundation? 5) Heating?

1) You will have the same amount of roof structure, except it will be divided with some on the top of the first floor and some on top of the second floor. In addition, it’s more complicated (and expensive) to tie the lower level into the second floor wall and flash it properly.

2) You’ll have a few longer walls. This wall area will require a finish on the interior and exterior.

3) The second floor framing will need to be larger in order to support the second floor walls and roof structure.

4) The foundation will need to be the same size and support the same amount of roof load and nearly the same second floor - floor load. No savings.

5) You’ll save a small amount of space heating, but insulation will be more difficult to install and not as efficient.

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