A building's roofing system should be at the top of the maintenance priority list for every building owner and facility manager.  It is, after all, through undetected and unresolved defects and/or damage in a building's roofing system that water oftentimes penetrates to the building's interior.   Furthermore, a defective roof, is often the cause of deterioration to other parts of the building's exterior, as water will travel through the roof into adjoining walls and cause structural damage to other aspects of a building. The key to assuring the maximum functional life of the roofing system is by having a regularly scheduled maintenance and inspection program in place, conducted by a qualified roofing professional.  The roof inspection should be performed at least twice a year - in the early spring to note and correct damage that occurred during the winter, and in the early fall to prepare the roof to withstand the onslaught of another winter.  Additional inspections should take place when events occur that would indicate roof damage or potential damage, such as after severe storms or when there are leaks in the building. A good time to conduct general maintenance roof inspections is within 12 hours of the last rain so that the damage will still be obvious.  The qualified roofing professional's program of inspection and preventive maintenance report should include: * A roof plan that accurately shows existing roof mounting equipment; * An evaluation of the general condition/appearance and life expectancy of the roofing system; * Photography that documents problem areas. The report should include a checklist that addresses the type(s) and seriousness of problem(s), observation(s) relating to the problem(s), and the condition of and recommendations for the following items (when indicated): * Structural deck/deflection which could result in ponding * Condition and effectiveness of drains, gutters, and downspouts * Physical damage to the existing roof system * Flashing * Expansion joints * Fascia * Penetrations * Pitch pans The inspection report may then be used to develop a maintenance schedule, which often covers a period of several years.  The schedule should immediately address the most serious roof problems. The inspection and maintenance will allow you to anticipate the future need for resurfacing, therefore enabling the planned allocation of funds in an orderly manner.  When the roof has neared the end of its useful life span and can no longer be maintained economically, replacement should be scheduled during good weather months. A regular program of roof inspections, surveys and preventive maintenance is the only sure and cost effective way to maximize the useful life of a roofing system.  The costs associated with this type of program are minor compared to major repair and replacement costs which will prematurely occur if these items are neglected. Protecting the structural soundness of your property and the investment it represents is critical to every building owner.  Preventive maintenance of the roofing system must be a top priority that can ensure the integrity of the building, minimize water damage, and lower costs. When is it time to replace a roof VS. repair it? In evaluating when it is time to replace a roof versus repair it, many factors should be considered and questions must be answered.  How widespread are the problems? Are leaks confined to one area or in several areas? If leaks are spread out over the entire roof area, it is an indication that the roof system has problems that are not cost effective to repair. Where are the problem areas? Do the leaks show up around roof projections, such as plumbing stacks, roof fans, skylights, parapet walls, etc.?  If so, it is possible that the problems are with the flashing.  However, don't be fooled.  Depending upon the number of roofs and the type of roof deck (such as concrete or steel) water may travel between layers and show up in the interior at an opening around a roof projection.  If the leak shows up on a surface where there are no roof projections, it is likely that there is a defect in the roof membrane itself. Does the roof pond water?   According to the National Roofing Contractors Association, any water that stays on a roof 48 hours after a rainstorm may be detrimental to certain types of roof materials. Dennis Kulesza is president of Metropolitan Restoration & Waterproofing Corp., Boston, Mass.