Can you copyright construction documents by placing the word copyright with C and little circle around it on the title?

Answer 1

The creator of any design, composition or artwork is considered the original 'publisher' until the creator assigns his publishing rights to an administrator. You have the copyright on anything that you create from the moment it is creqated or displayed publicly. However, the copyright symbol alone is not a copyright, nor is it proof of the date of first publication. The symbol merely announces the name of the claimant and makes others aware that you care enough about this idea to announce it formally.

Construction documents may be in the public domain, depending on what they were created for. Designs and plans are certainly [eligible for] copyrighted.

However, simply making a copyright mark on the original document won't protect your intellectual property in the event someone should plaigerize your ideas or designs. Unless you register your copyright with the Library of Congress you will not have the proof you need that you were the original creator should a dispute arise about the origin of your idea.