I am trying to design a cabin based on website: Https://archedcabins.com. In this case a 30x40 cabin with arched walls that at the center point is 17' I thought perhaps using the arc on the walls would do something but that is for a curved wall outward/inward depending on design. In this case, I need to start at the foundation and curve upward and inward to 17' and then back down to other side so that it is symmetrical.

Any help would be appreciated.

Thanks

Tim