The problem for those of us who don't know this stuff is how to pick the right inspector / builder. There are dozens of examples in this thread of conflicting advice from people who claim to know what they're talking about. Tyvec is the problem. Tyvec is good. Insulation causes the mold problem. Insulation prevents it. Insulation has no effect either way. Metal studs are the problem because they don't retain water. They are the solution because they don't retain water. Stucco causes it. Stucco doesn't.
When I bought my two houses, I hired an independent inspector because I'm pretty ignorant about construction. Things I thought would be problems weren't anything to be concerned about. Stuff I wouldn't have thought twice about were big issues to my inspector. Best money I ever spent.
But what I'm hearing from this thread is you need to get an inspector/builder who knows the answers to these issues, but no one seems to agree on what the correct answer is.
I would start by learning about homes. Learn the basics - get a book such as "Encyclopedia of Home Improvement" or "Carpentry and Building Construction". They will get you started on the basics.
You'll find that there are various theories on such issues as whether to use a vapor barrier or not and whether to seal the attic or leave it ventilated (yes, there are advocates for a sealed attic scheme). Understanding the basics helps you understand how these theoretical schemes are supposed to work.
Also, a couple of the links that were presented here by Restorer and others provide a host of good information. Read them as time allows and you'll be better equipped to deal with inspectors. You may even point out a few things to them to let them know that you're not just another pretty face. :^)
As one of the people in question, I sympathize with your problem.
May I suggest a couple of excellent resources?
Moisture Control Handbook by Joe Lstiburek. Available from Amazon for less than $20.
www.buildingscience.com
If you understand the concepts discussed in these resources, you will be able to tell whether your architect, builder or inspector also does.
Good luck, almost none of them do. And that includes highly educated architects and very experienced builders, even when they're highly ethical.
Their training and experience has just been in other areas. An example is the architect on this thread who claims that insulation is a cure-all for moisture and mold problems.
I am aware of one builder in OH was forced into bankruptcy because he switched to a wall system which increased the R-factor by about 20%. That small increase tipped the assembly over the edge, and structures began literally decaying in a couple of years.
400 homes later, at an average remediation cost of $30k, he was out of business and the buyers were out of luck.
Moisture control wasn't a big problem in mild climates before the 70's. Houses were so leaky that air infiltration took care of any buildup. The energy codes changed all that.
In cold climates, moisture control has always been a problem. Human occupancy generates moisture from transpiration, cooking, bathing, etc. This moisture needs to be removed from the living space, or it will condense on the first cold surface it finds. It may be a cold water pipe, a window frame, or the building sheathing. If that surface is within a wall, rot and mold will follow, and exterior paint will peel.
To do the job right in a cold climate, the vapor barrier should be on the inside of the walls, and completely sealed around electrical outlets, light fixtures and such. The tightness should be verified with a pressure test. The outside wall surface should keep the weather out, but be able to "breathe" so that any moisture that does get past the primary barrier can escape.
The reason that you see so many varying opinions on this problem is that there is no one-size-fits-all solution to moisture control. There are about a zillion books on moisture control in buildings at amazon.com. Here is one at random:
Moisture Control Handbook: Principles and Practices for Residential and Small Commercial Buildings