Who is qualified to do a roof inspection for a home owners policy?

Your best bet would be to contact a licensed roofing contractor and ask for a "roofing certification". Expect to pay around $300 for the certification. The roofing contractor will visit your home and do a thorough analysis of the roof and provide you with report which should indicate the type of roof, number of layers, any deficiencies noted, and finally, what the life expectancy is of the roof covering. Essentially, they are "certifying" that the roof last X number of years.

Contrast that with a roof inspection that could be completed by home inspector. You can expect to get a very similar report from your home inspector including most of the items noted above, the exception is that a home inspector will not provide any type of certification on the roof.