If we have a mild winter, they get sufficient moisture, you supply some sort of protection, and you're extremely lucky, they may survive. While a 14 inch pot may sound big, the potting mix freezes from the sides also. Freeze/thaw cycles can break up the roots killing the roses.
I attempted to overwinter a number of potted roses outside. They were protected by a stone wall and covered with oak leaves. Many died, many survived but were never the same, while a few made it with no apparent problems.
Know anyone who has an unheated barn or shed you could store them in? You'd have to visit occassionally to water but they'd have a better chance to survive.
I have great luck storing mine in an unheated greenhouse. The soil freezes solid but the roses survive and come back strong each spring.
You could try a cold frame of sorts, made from two inch thick extruded poly styrene and covered with clear plastic. You'd still need to water but my 200 newly rooted cuttings survive in a really large one built the same way.

I bury my potted roses over the winter. I dig a pit deep enough so that when the pots are in the pit (upright) the bud graft is four to six inches below normal ground level.

After the ground freezes, I cover the roses with bagged leaves. I have been doing this for years and only have lost one plant when I was late in removing the leaves in the spring and serious canker set in.

I have not had any luck overwintering roses in an unheated and detached garage. I am tempted to try the foam insulated cold frame idea because the digging gets more tiresome every year older I become.

Regards,

Charles