Project Zero, Sea Level, and Floor Level settings

[EH21]

Probably a silly question, but what elevation do you set Altitude (Sea Level) to in the location settings? Do you select main level floor level or some average elevation point? Then, what is your project zero? Is it based on sea level or a floor level?

Operating system used: Mac Apple Silicon 14 Sonoma

[Marc H]

Hi EH21,

As a general setting, the Project Location values do not interact with the model.  The Survey Point, in contrast, does establish a reference point in your model. 

For the Project Location Altitude, therefore, I typically use a general, rounded ASL number. This can be from the existing land survey, or if not available, the jurisdictional GIS system, or even an approximate ASL derived from another source (e.g., online map site).  For the Survey Point in a building site PLN, I use the land surveyors benchmark (monument), preferably SW of the building site, or an established SW corner of the building if a building PLN on a campus project.

As to the project zero level, yes, I set this to equal the main building entry floor level.  I add the ASL in the story names (e.g., “MAIN FLOOR [455.50’ ASL]”).  By default, these ASLs will then appear on all the sections while I am modeling, which I find useful for cross-reference with survey and engineering information.  Whether the site mesh is assigned to the main floor story level or a separate 'Site' home story, I set the mesh top surface to match to the topographical elevations.

Hope this helps.

[FionaClark]

Thanks for helping me out, you made my day.

[Patrick M]

Main floor level = project 0. This builds a correlation between 0,0,0 and your story settings. In split levels, daylight basements, etc. you may need to assess where project 0 makes the most sense, but in most cases, I set the story that is closest to street level to my 0' to project 0. I never adjust the elevation of first floor/main floor/etc. above or below project 0 in the story settings.
THEN all you need is to set your project location (altitude/sea level) to your project 0. After that, if the floor level changes, you only need to move the site model up or down to account for the change in elevation and update your project location settings.