Doors and Windows - Installing Exterior Steel door in garage with cement subsill?

We currently have a wooden door in our garage that is rotting and I want to replace it with a steel door.

There is currently no subsill under the door, just the cement slab.

What would be your recommendation on how to approach installing a new door in this situation?

Thanks,
ScAndal

Tear off the old trim, remove the old door jamb, and replace it with an exterior prehung. It will come with its own sill. An adjustable threshold is a feature all doors should have, IMO, so look for that when you buy your door.

Thanks XSleeper!

That is what I'll do. Would the new Prehung steel frame require me to nail into the concrete through the subsill, or would that just set on the concrete?

ScAndal

It'll say in the instructions for the door. Some people like to use Liquid Nail, some use butyl rubber caulk, some use silicone. Normally you put 2 or 3 beads on the ribs of the sill. If it has a solid sill plate on the bottom, put 2 or 3 -3/8" beads near the exterior and along the edges.

No screws or nails thru the sill, nail through the trim and frame. Also make sure you use the long screws that come with it through the hinges into the studs.

Last thing, watch the height of your rough opening, Sometimes theres not enough room for a std 80" door (which requires an 82" opening) and you have to go with a 78" or change the opening.