I always joke that having a boring day is good for a home inspector and thought that I had it made on a new home - until I got in an attic and saw that there was no water resistive barrier and new siding. I could literally see the neighbor's house from a crack between siding pieces. Not good. In the bad old days before 2003, the IRC (International Residential Code) did not specify water resistive barriers for homes, leaving the details to the siding manufacturers. Some manufacturers required them while others were willing to certify their exterior wall coverings as primary water barriers. The differing standards led to different installation procedures, mass confusion and a slew of houses vulnerable to water intrusion.
So the codes changed.
Which brings me to a new home and no barrier. It should be there. It's in the code. It's also in the installation manual:
A properly installed breathable water-resistive barrier is required behind the siding.
Seems pretty cut and dried but I know that my clients will end in a battle - because this is not an easy fix. Correction will mean removing the siding (they're supposed to close this week!) The builder will likely make two arguments - the first, that he is adhering to the standards of practice for the region. Therefore, the buyers should not expect any better. This one he might win - others have, claiming essentially the same thing. "Yeah, it's wrong but everybody does it."
The second argument will come from a misinterpretation of the siding installation instructions. The manufacturer allows the siding to be nail directly to wall studs provided they are 24" on center or less - which is the case in this home.. It doesn't mention the water resistive barrier expressly so I expect him to claim it isn't necessary. It's a pretty bogus argument, but the builder is in a bind.
This happened on new home construction but I can see a potential for problems on remodels as well. When upgrading the exterior, you need the water resistive barrier. They work together. Some companies will try to cut costs - and the barrier can be a bit expensive - and, unless conditions are perfect, there is no way for the average home inspector to know. Yesterday I had the conditions and made a good catch that will save my clients a ton of aggravation a few rainy seasons from now.