Exactly What Determines Ceiling and Roof Height?

Roofs continue to confuse me. I'm using Home Designer Architectural 2014. I'm presuming there is no way to change the "thickness" or actual material of roofs? They appear to be 2x6, without being able to be changed, is that right?

As to height, I know that I can select a Room, and from its properties determine the rough and finished ceiling height. I'm assuming that somehow that determines the height/location of the roof. But as each room could have a different ceiling height, or no ceiling, and that doesn't result in multiple roof heights. So what, exactly, determines the roof height (not pitch, the height at the walls of the house)?

Could ceilings even be several feet below the eves of a roof, like in a drop ceiling? If so, how is that accomplished? The difference between the rough and finished ceiling height is normally just drywall thickness, but would it be changed to 24" or something to do that?

Oh, and what does the "Use Soffit Surface for Ceiling" in the Room Specification > Structure do exactly? I assumed, by the description, that it would make the inside ceiling height the same height as the outside roof soffit. But, it doesn't appear to, and in fact the outside soffit is always sloped (one of my complaints) rather than level, so I don't know how it could be.

I read the help, which says: Check Use Soffit Surface for Ceiling to improve the 3D appearance of the transition between ceiling and eves of exterior rooms with Ceiling Over This Room unchecked.

I've played with it and haven't yet found a difference.

In Chief Premier and HD Pro you can specify all framing thicknesses and layering, in all other Home Designer titles, you can't.

Generally the ceiling height settings in Default Settings - Floor - Structure Tab - Ceiling Height determine or "tell" the roof generator where to place roofs in terms of plate height. You can make individual ceiling height changes per Room Dialog box - Structure Tab - Ceiling Height per room as you require but setting the Default Settings - Floor - Structure Tab - Ceiling Height is the first place to control that in all titles and versions.

DJP

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Originally Posted by David J. Potter

Generally the ceiling height settings in Default Settings - Floor - Structure Tab - Ceiling Height determine or "tell" the roof generator where to place roofs in terms of plate height. You can make individual ceiling height changes per Room Dialog box - Structure Tab - Ceiling Height per room as you require but setting the Default Settings - Floor - Structure Tab - Ceiling Height is the first place to control that in all titles and versions.

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That makes sense, to make it the default first, then change any rooms required. I played around, and found I can get the lower ceilings and higher roof by changing the Ceiling Finish Thickness. It's a bit cumbersome, because even if you've changed the thickness, changing either the rough or finished height changes the other. But if you change the rough opening as desired, then calculate the finish thickness you need to get the finished height, it can be done.