Can I overlay a driveway with alligator cracking?

Not over the alligatored areas. That pattern means the base has failed and the pavement is flexing, and an overlay adds surface rather than structure — it will crack through in the same places within a couple of years. Those areas need to be removed and rebuilt first.

Does an overlay raise the driveway height?

Yes, typically by the thickness of the new layer. That matters at garage doors, thresholds, drainage structures and where the drive meets the street. Milling the edges is how a good contractor ties it in without creating a lip.

Overlay or Full Replacement? How to Tell Which You Need

This is the biggest number on most paving decisions, and there is a genuine answer that does not depend on who you ask — provided somebody actually looks at the base.

What an overlay is

A new layer of asphalt placed over the existing surface, typically after milling the edges so the new surface ties in at the right height. It gives you a new surface at a fraction of the cost of removal and rebuilding.

It works on one condition: the existing base has to be sound. An overlay adds surface, not structure. Over a failed base it fails in exactly the same places, usually within a couple of years.

The test

Alligator cracking anywhere significant means base failure. That area cannot be overlaid; it has to come out.
Depth of distress. Surface-level cracking and oxidation is an overlay candidate. Cracking that goes right through with movement between the sides is not.
Ponding. Standing water usually means grade or settlement problems, and an overlay follows the existing shape — you will get a smooth birdbath.
Movement underfoot. If the pavement flexes when a vehicle drives over it, the base is not supporting it.
Height constraints. An overlay raises the surface, which matters at garage doors, thresholds and drainage structures.

An overlay over a failed base is not a cheaper repair. It is the same repair, done twice.

The middle option

Frequently the honest answer is neither extreme: remove and rebuild the failed areas, then overlay the whole surface. That is more expensive than a straight overlay and far cheaper than full reconstruction, and on a lot with localised failure it is usually the right call.

What to ask for

Ask any contractor recommending a full replacement to show you why — where the base has failed and how they know. On a commercial job that means cores. On a driveway it means opening a test area. A recommendation nobody can justify with evidence is a recommendation worth a second opinion.