Vent flashing

Recently , I had a roof done by a professional roofer. On some of the vents the exposed portion of the flashing was nailed to the roof( I assume to hold it down) and on other vent flashing the exposed portion sets on top like a shingle. I plan to seal the exposed nails, but I am wondering about the flashing which is not nailed. When lifted up slightly it appears not be cemented to the shingle it’s on top of. Should I use some roofing cement under it to keep it from leaking in the event the wind blows and the rain comes sideways.( it is loose enought to get under it and apply some type of adhesive) Should it be nailed down? The roofer agreed the nails should be sealed, but I could not get a straight answer on the cementing down of the exposed vent flashing that sits on top of the shingle. Any help would be appresciated.
Thanks,
J

It sounds like it is put in wrong.
Can you post a picture?

I agree with ax that does not sound like it was installed right. If any of the 3 sides of the vents are exposed it is dont wrong. The bottom is supposed to be open and nailed down with sealant.

Hi,

There is most likly nothing wrong.

There are little pockets where the nail goes. This prevents leaks. You can add a dab of sealant, if you want.

The one that has no nail showing is propably nailed right under the shingle so it is not exposed. These are judgment calls that we make while we are installing each individual pipe collar.

A picture will let us tell you if it was installed correctly. Anything else is just rumor.