I ended up insulating the garage several years after buying the house. Snow melt became too much to handle. Many times I would have 20 to 30 gallons on the floor. I borrowed a concrete saw and made two parallel cuts from a central low spot to the outside frost wall, busted out the concrete...
I am having a snow melt/standing water problem too. Too much moist air condenses on the window and runs down to bottom of the doors and freezes the door gasket to the slab. I broom it out the door and freezes on the driveway...bad. I **** it up with the shop vac...big pain I dumped 20...