Good morning all. Yes the original posting is further back and many have added fresh new comments. Many of the comments are correct and many are in the "shady/grey" area.
Fact 1: The IRC/IBC code is not designed simply as a code for "DIY" people. The code was written for anyone who wants to build BUT it is the MINIMUM STANDARD REQUIRED to construct a building in order to provide for the safety of the inhabits of the structure, whether it be a residential or commercial structure. ANY construction above and beyond the minimum code is always acceptable and in some cases often recommended.
Fact 2: A licensed Architect/Engineer is one who is willing to bear the responsibility aka "cost" of a mistake in the preparation of the plans if it accidentally causes a failure in the structure leading to substantial loss, whether it be damage to the building or loss or life due to the structural problem. Even if one is not willing to become a licensed architect/engineer but still wants to design, my recommendation is that you at least have E & O insurance or have a contract that you have the client sign that would release you for any responsibility of a failure.
Example 1: Recent client I have comes to me to re-design certain aspects of a 15,000 sf custom home that was designed by an architect. The original architect made several dimension mistakes and didn't design to the client specifications on the way it was supposed to look...contractor built by the plans...structure now leaks, hallways do not align, and foundation (not design by PE) sank in one area causing the interior balcony and subsequent roof area to fracture and numerous other errors. She is suing BOTH the architect and the contractor for MILLIONS.
Example 2: I recently completed a design for a client, a remodel-complete gut job. I myself have an engineering degree and am a Certified Professional Building Designer with my own seal, my husband is a licensed Mechanical & Structural PE with his own seal. We did the design & engineering for the house, the foundation, truss work for the new elevated roof, and other aspects. We both spent hours designing and ensuring everything would work out right. He especially put a lot of time in the calculations for the new roof and the footings etc. To get the loading right and prevent: racking, sheering etc. etc. Everything was good until he went for a site visit. Contractor and his framers took it upon themselves to ignore the calculations and use smaller lumber, they took it upon themselves to relocate the position of the collar ties, they took it upon themselves not to follow the prints for numerous things because it might save a few bucks. My husband came back and re-did the calculations based on what they did. The result is that what they did will be a failure. Their response: "we've done it this way for years" and nothing has happened yet and the client wants it." That little word "YET" has big consequences when it does happen and who do you think the client will turn to for compensation? We do not follow specific charts, tables and guidelines and mathematical calculations for construction materials just for kicks. We design & calculate to avoid the "yet". As the Engineer of Record, Legally my husband can walk down to the building/planning office and fill out a form and tell the building inspector to post a stop work order. They will have to completely stop the construction, tear it all down and start over and built it to print, which will be COSTLY. However, since he is a fairly decent fellow, he does more calculations and comes up with another solution. They have to add in additional lumber, follow the proper bolt size and pattern to make up the difference. Not as expensive as a complete redo but it will cost more now than if they had followed the prints in the first place. Now, unfortunately, we're going to have a CTJ meeting with them this afternoon about following prints and engineered guidelines. If they fail to adhere to the the design and engineered specifications-we walk. Not a good situation for the client as they have to start all over.