Foam Injected is also called Polyurethane Injected Garage doors. Polyurethane insulation is often referred to as spray foam. Although a newer product than polystyrene, it has caught on quickly due to its high efficiency and ease of use.
Polyurethane is sprayed into each panel and makes a very tight fit which will add to the rigidity of the panel when it is new giving it a higher R-Value. Pressure-injected garage doors with polyurethane foam have R-values between R-12 and R-18.
Polyurethane is the more expensive material of the two but doesn’t usually add too much more money to the price of the door. It is important to make sure that the steel skins of the door are not too thin because two things could happen. One, the door will dent easily or two, small waves will appear across the sections and can generally be seen within five feet. This will obviously make the door not look so hot.