Where do you plan to build? 

Yes, an architect and engineer can help you if you know what you want.  However, you may not need an engineer or architect.  It depends upon your local requirements and the design.  If you are building in my area, then I can donate some time to your project or at least answer your questions.

My e-mail address:
Alton at Auburn dot Edu 

If you already have the design and you like it, then it is unlikely you need an architect, although a good one could probably make many improvements and suggestions while they draw up the set of plans. An architect definitely has the skills and knowledge to take your concepts and help make them a reality.

Just a set of plans could be handled by a good draftsman, but unless you've got everything correct on codes, you would do well to have a home designer touch it up and generate the plans. Either way, you will need someone with an engineering stamp to verify structure.

Whatever you do, make sure you get an architect or a designer or even a draftsman who is familiar with ICF construction. It will most likely save you loads of time and cost during the build. What I found was that everyone claimed they could do ICF, but only a few really had enough experience to actually pull it off. That means you will have to get into the ICF community including the distributors to find out who does ICF and who does it well.

Depending on where you plan to build. you may need one or the other if the plans need to be stamped or none if the comunity do not require and you can save some money that way. I build custome homes with icf and much more. I am available as consultant if you want just email me.

I would suggest the engineer, but make sure s(he) is experienced with ICF. Last big project I did I hired one of each, the engineer just told me to build it as I drew it and I could have his stamp. The architect wanted to change my design. I found I was always arguing with him, not a satisfying experience. My current project is a DIY ICF house, and again I did my own design, but this time didn't bother with an architect. I did need a stamp so the planning department would let me go, so I hired an ICF experienced engineer. He made a couple of suggestions to the roof structure (which is wood frame) which saved me more in construction then he cost, so money well spent. Of course YMMV.