Many garage renovations begin with a primary goal to improve the bare concrete floor. Fortunately, there are several solutions available in a wide price range.
Paint and epoxy
Paint provides the fastest and easiest floor upgrade for a garage. Latex concrete paint often called "porch-and-floor paint" offers a quick, inexpensive, and colorful solution. As long as you don't plan to share your garage shop with a car (hot tires can damage the surface) or otherwise abuse it, concrete paint may be right for you. Depending on brand, a gallon sells for about $30.
Epoxy-based coatings, extremely hard when cured, are among the most durable options. A one-part epoxy can be applied straight from the can, while two-part epoxies (resin and hardener) must be mixed thoroughly before use. A two-car-garage kit (500 sq. ft.) that includes floor cleaner and two-part epoxy and sells for about $120.
Whether you apply paint or epoxy, the floor must be clean, dry, and free of grease and oils, or you may find the coating will peel up with the first change in weather or humidity. Proper adhesion of most epoxy products also requires a thorough process to provide "tooth" for the epoxy to bond to the concrete. A chemical etching is the most common DIY approach.
Professionally applied epoxy coatings may cost in the range of $3.50-$5.00/sq. ft. for a two-car garage. The price is higher because industrial-grade epoxy is 100 percent solids (no fillers and therefore no odor during application) compared with about 20 percent solids for the DIY product. The industrial-quality epoxy wears longer and isn't subject to hot spots (DIY epoxy can bubble up) from hot auto tires.
After a thorough cleaning, professionals will roll on two or three coats, compared with one coat for the DIY products.