Mansard Roofs & Porch Overhangs

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Hi All,

The 3-story building I am modeling has a flat roof with a decorative
mansard roof extending above the flat roof by about 4' and going down to
the bottom of the top floor. In addition, there is a porch wrapping
around the East & South side of the building with an overhang which is
attached to the building.

Can anyone shed some light on how I can incorporate these elements into
my model? An overhang won't work because they are not based off windows,
and in the case of the mansard, roof surround the top floor windows.

I've attached 2 dwgs showing these conditions. Help?!

Thanks,

Lori Dowles

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Lori,

I would model the third floor mansard roof as a vertical exterior wall
with a different construction (and new construction layers). Enter the
appropriate setback distance for the windows in the mansard roof. You
can model the 4' mansard roof extension and porch roof with building
shades. (In DD Edit mode, within the Building Shell module, right-click
on the Project in the Component Tree and select Create Building Shade.)

Regards,

William Bishop, EIT, LEED(r) AP

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I would model this as a roof parapet (wall extending above roof height). You
could change the construction type of the mansard section of the walls if
they have different thermal characteristics. It is an energy model, not an
architectural model, and the very slight tilt of the decorative wall is
probably not significant from an energy point of view.

Porches are typically included in the building footprint, so they could be
modeled as unconditioned spaces with large openings in the walls.

Another way to do it is to only model the porch roof by defining a polygon
that is outside the building footprint, and assigning a roof construction to
it, but there would be no "porch space" in this case.

Rob Rosen

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Thanks everyone- appreciate the help!

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