The average service life of a conventional flat roof is somewhere between 10 to 20 years. But no roof can be expected to last its full service life without regular inspections and maintenance.

Through periodic examinations of the roofing system and preventive maintenance, a roof will perform predictably and last far beyond its expected life. On the other hand, neglecting a roof increases the chances of early failure and the inconvenience of leaks.

In short, your roof will last as long as you are willing to take care of it.

Excerpt from national Research Council's: ''Roofs: Design, Application and Maintenance'', 1980, by Max Baker.

All conventional flat roofs are exposed to surface deterioration under the action of sun, wind, driving rain, hail, ice and snow, traffic, building movement, temperature cycling and water ponding. It is because of this process of degradation that a roof must be inspected yearly. When a leak occurs in a flat roof, a more serious type of deterioration occurs. Even if water does not enter the building, it attacks the insulation. Destruction of the roof system can progress rapidly and cause damage for which repair is costly or impossible. This phase of deterioration is neither inevitable nor normal for a properly designed and constructed roof, and usually is merely the result of neglect and lack of maintenance.

It is difficult to comprehend how a roof, which is an expensive element of the building, can in many cases go on unattended for years. It is similar to buying an expensive car and being content to only add gas when necessary. Both car and roof will fare miserably before they reach half of their designed life. A roof may cost $100,000 with a 20 year designed life. If through lack of maintenance the roof fails after 10 years, this result more or less in a $50,000 loss. Is this good management?

H.E. Saint-Amour, technical director of the Canadian Roofing Contractors Association, Canadian Roofing Contractor, vol.3, no.1, 1986.