The bottom portion of your garage door is most susceptable to this kind of wear which can lead to water damage and wood rot.
Garage door exterior surface cracked.
You are more apt to see these types of cracks on a garage floor that has a hard smooth troweled surface than one that has a broom finish.
Actually fixing a crack in a garage door panel can be a difficult and even impossible task.
Repairing the doors requires a little work and depending on how large the crack is could be.
If your garage door is metal or vinyl it is much more difficult and even impossible to fix.
Caulk paint cracking or crawling the cracking of the paint film over a caulked area.
Loss of caulk s initial adhesion and flexibility causing painted caulk to crack and or pull away.
Cracking due to poor compaction of sub grade before pouring a concrete slab it is important to prepare what is often called the subgrade which usually involves compacting the sub grade and base i e.
Gravel and or sand on top of the sub grade.