Legal questions should be asked of an attorney.

All the issues you raise - and many additional ones - should be negotiated with the other party and covered by your contract. These are clearly legal contract issues for negotiation and you need a negotiation strategy. It is not fair for you to get paid for one plan and have the builder benefit from it 20 times, but that may not be the position taken by the builder. You should also be concerned about your potential liability to multiple third part home buyers you have no contract with, which can vary from state to state. You need a reasonable attorney with subject matter familiarity and experience and good negotiation skills, as there are multiple issues and trade offs in this scenario.

Thank you for your comments. I will be negotiating terms with the builder and getting my lawyer to review but I would like a general idea of what others have done in this situation so I know where to begin.

"Architectural Technologist"

This is Canada right?

@millworkman yes, Saskatchewan

I know nothing of the copyright laws in Canada but in the US you would automatically own your work product unless you performed it as a "work for hire", meaning you were an employee instead of a consultant.