Most residential or commercial concrete foundations are strong enough to support a QuickJack. If using on asphalt or compacted and dry dirt paddock areas use 3/4" plywood under each jack frame. A level floor with 2-degrees of slope is suggested for safe use. If a floor is of questionable slope, consider a survey of the site and/or the possibility of pouring a new level concrete slab. In no event shall QuickJack be liable for special, consequential or incidental damages for the misinterpretation of this information.