Fiber glass and mineral wool batts require almost no downtime, unlike spray foam and cellulose, which are applied wet and require at least 1- 2 days to dry or cure before drywall installation can begin. In some cases, spray foam takes a week or more to completely dry out. Moreover, other trades can continue working during installation of fiber glass and mineral wool batts, whereas spray foam installation requires evacuation of the entire structure during installation and up to 72 hours after. All this downtime with other insulation types gets expensive. The NAHB estimates the average jobsite builder's operating cost per day is $291, with some builders saying that figure is up to $500. Every construction hour counts, and fiber glass and mineral wool help you save time and money.