Most roofs often last between 15-40 years before a massive overhaul is necessary if constructed well. However, if the workmanship was poor from the beginning, you may need to replace your commercial roof much sooner than this. Other things that could damage your roof include fires, falling trees and storm damage just to mention but a few. Either way, replacing a damaged roof is good for your safety and the longevity or the building as well.Roof repair and recovery works well for roofs with minor damages. However, you cannot recover the roof more than once, if it is damaged again, you need to replace it. The rule of thumb for roof replacement is extensive damages that cover 25% or more of the roof should call for a roof replacement. You should also replace the roof if the insulation is damaged or wet. Roof replacement is a long-term solution and gives you the chance of using the latest technologies to improve the condition of your building.Before your start working on a roof replacement, is your roof deck strong enough to handle the new additional weight or equipment and even workers during the replacement process? If you have a strong roof deck, then you can choose any roof that can be installed over the old system. If your roof deck is weak and worn out, you will need to repair or re-install a new one before replacing the roof.The slope of your roof will determine the kind of roofing system that you can use to replace the old one. If your roof is too flat then materials such as shingles and concrete tile are not a good idea since they need quick water runoff. Find out from your roofer, which materials work well with the slope of your roof to provide the best function possible.Another important thing to consider when it comes to roofing is drainage. Proper drainage is important to avoid standing water on the roof surface. The weight of the water may cause the roof to warp and collapse. Moisture damage is also another problem associated with water that you do not want in your roof. If you want to change your current drainage system, you may need to make changes to your roof deck and find a versatile roofing system.For most commercial roofs, there may be some additional structural load on the flat roof. This expected structural load should be determined before replacement to avoid overbearing the roof in future. A restoration coating alone cannot add to any strength of the roofing systems; spray foam or SPF on the other hand may be what you need if you expect heavy loads like cars driving on the roof surface.Finally, the potential wind up lift should be analyzed to determine the best roofing type for the area. The potential wind uplift is determined by the expected wind speeds in the area and the wind resistance in the roofing materials. Roofs with the appropriate uplift resistance should be used.