Rough draft: more to come
You need an engineer
If you are going to be putting tons of concrete and earth over your head, you should probably hire an engineer. Its not just a good idea, in many cases, it will be the law. Your building inspector will probably have no idea how to judge your home and will want to see that engineering stamp. As with hiring an architect, having a professional engineer on your team will probably also help things go smoother with the banks, neighbors, family, etc.
I am an engineer myself, so it is sort of like a doctor going to the doctor (doctors make the worst patients), but I knew it was necessary.
An indirect relationship
The architect will want to hire the engineer themselves. This will allow them to work more closely together due to the direct connection. The architect probably has more leverage with the engineer because he can choose to hire him again for another job much more quickly than you will. So let your architect hire the engineer, but you should know what you are getting before you agree to it.
There were two main engineering companies in my smallish town. The one actually said he had experience with “concrete shell”, but my architect didn’t like working with him because he preferred to charge by the hour. My architect preferred to work with other engineer.
I spoke to several earth sheltered engineering companies about working on my project, each was associated with a particular earth sheltered construction “kit”. They were not at all interested in going outside of their kit or providing engineering services without selling the whole kit. I assumed they tuned their engineering to the kit so they could be more affordable, but I later discovered that they still charge more than $20k in engineering fees in addition to the cost of the kit. I ended up working with an engineer who had never earth sheltered anything, willingness to take on my project was his primary qualification…
So what can you do to ensure that things go smoothly with the engineer? I think establishing some mutual understanding up front would have been a good idea. If you want the engineer to help with the design, make that clear and be ready to pay for it. If you just want them to just sign off on the design, make sure that is clear. Most importantly, make sure they understand the mutual arrangement. If you want them to help with the design, develop a mutual understanding of the design philosophy.
Since the architect already knows what they expect from the engineer, find that out also.
My saga is still on going, but this was my biggest mistake. I don’t think I communicated with my engineer in the way that he needed and that cost me time and possibly money. The lack of clarity about the source of the design or the design philosophy caused lots of problems. I will come back and complete this page, so you can benefit from my mistakes, when the engineering phase is over ;^)