Possibly the easiest way to pull this off is going to be with a blended mass that has a roof system hosted to it. The process is pretty straight forward but can be less than obvious. Simply start an in place mass family and draw your oval bottom in as well as a small circle for the top. This will leave a small gap at the top but it will not be noticeable in final documentation and thus should not be an issue. Move the small circle up to the top of the blend and then simply select both objects and hit create form. To get more definition out of it you can create several profiles along the height to create a lofted extrusion that will follow the separate profiles. I have created a small video that should illustrate the process pretty well.

http://screencast.com/t/yDllZ4kA

If you are looking for more complex dome shapes you may be looking at using a couple of mass sweeps within the same in place mass that are joined together. Mass sweeps can be created by sketching a path in the plan view and then a profile that follows the path in an elevation or section view. Then to create the sweep select both the path and the profile and use create form.

Great video hypnox1 - But thats´s more like an eliptical cone (not dome)

I was actually trying to make a true eliptical dome last night, but failed - even with the conceptual massing tools.
If the sectional curve at the top dosn´t need to be elipse shaped, it could be done as a revolve...
Would love to see THE right solution for a true eliptical dome ! :beer:

Try this for a stapoint Dome Mass.rfarting

I have not attempted anything, but was thinking about one of Phil Reads' AU presentations this last year. He was able to create some crazy forms by starting with a big mass, and then using voids to create the final shape he was after...Class ID: AB326-1V

http://www.screencast.com/users/Duel...9-74b1dcea66bf

Watch this vodeo

Awesome ! But how in the world did you create the form element ? Tried to disolve and recreate, but no luck - which lines do I need to pick to create the form element in one piece ?

Yea, I was sure it wasn't the exact shape that was wanted. However, more profiles can be added to modify the shape. Even with a lot of work I've found that oval domes will basically never perfectly appear as wanted. It's almost easier to produce the desired shape in a program like Rhino or Sketch-up and bring it in as a mass family in Revit.

However, I think the excellent solution posted by MWeideman proves that there IS a Revit solution. Exactly as specified: 20' x 40' in plan, 3' in height, and elliptical in plan and elevation.

This is the idea of how we figured it out yesterday I revolved a donut with the correct arch of the Dome form front to back (40' length) with the 3' rise in the middle. I figured that the outside radius of the Donut was the arch from left to right (Arch @ 20' length). so with a little math I got it to work out. I needed. So I cut a void that left just the top 3' of the dome shape left. Because the arches touched the outside of the circumference at the of the oval the rest was easy cut a void that left only the 3' top of the donut. then i just applied the curtain wall system to the generic model.

Thank you all for helping me I will keep this in mind for future projects. your post were very help full.