What are the expectations and how are the services being solicited and presented? I mean, could an appraiser be engaged to perform a home inspection based solely on their expertise as an appraiser? Doubtful, but theoretically possible. If it did go that way, such an inspection could technically fall under the category of Appraisal Practice as defined in USPAP even though there is no value opinion being developed. Much the same as teaching an appraisal course (no value opinion involved) also falls under USPAP because it is classified as part of appraisal practice. So in this appraiser-engaged-to-inspect scenario, none of the performance standards (SR1 - SR10) would apply, but the balance of USPAP would apply. Ethics Rule, Competency Rules, Definitions, etc..
I think most people would consider that scenario a stretch, though. More than likely, an inspection would stand by itself as a separate "valuation service", apart from Appraisal Practice as defined in USPAP. So there would be no "USPAP-compliant inspection service" and it would probably be wrong to solicit that type of work in that manner.
We don't generally have a problem discerning the difference between selling a property and appraising it because a realty agent acts as an advocate whereas the appraiser is supposed to be the disinterested third party. Those roles directly conflict with each other.
But what about a home inspector, who also asserts their work as being unbiased? I don't see a conflict in the roles. In fact, there were a number of articles published in the trade mags in years past about appraisers diversifying by offering hazardous materials assessments, radon testing, well testing and other related "value added" services in addition to their appraisal work. The idea being that a combo appraisal-radon test-lead based paint assessment service would be both more expedient and more convenient to the consumer than ordering separate services from separate vendors. If the individual had the expertise to offer the service, who better (in an ethical context) than an appraiser to offer the service?
How would it be if the value-added service were wrapped into the appraisal assignment as one of those "client extras" that contribute to the scope of work? Would having the elements of the home inspection available to the appraiser whilst developing their opinion of value add to the appraisal process? I'm sure it would in at least some cases.
As for separate services on the same property, that's where it might get a little murky. The different roles don't necessarily conflict with each other the way that brokerage and appraisal conflict, but there is the certification wherein the appraiser certifies that they "have no present or prospective interest in the property or personal interest with respect to the parties involved". Inasmuch as there is a prior or future prospect of performing an additional non-appraisal service on the subject and having a relationship with one of the principals as a result of that other service it might be argued that the extra relationship runs afoul of the cert. If that's the case then we can get into hairsplitting about including the services as extras in the appraisal, too.
Obviously, the way to avoid the controversy is to avoid the controversy - when appraising a property limit your service to just the appraisal, and refrain from engaging in other activities on that property lest it be perceived as a conflict. Either that, or wrap the extra service into your scope of work at the outset of the assignment and make sure the service doesn't conflict with the impartiality of the appraisal. Not a very satisfying answer for some, but it is the conservative approach.