It's a problem...

It doesn't always correlate that the bigger the visible challenge, the bigger the leak as even small leaks can cause major damage.  The best option for roof refurbishment is to identify when a roof is reaching the end of its serviceable life and take proactive action before water ingress occurs.  Carrying out a roof survey will identify the condition of your roof so that you can make an informed decision about proactive action.

Here are some common reasons for roof failure.

Standing water
The constant source of water can cause full roof failure. Any frozen water can also cause thermal shock to the membranes.
Membrane blistering
Pockets of air and moisture can expand with solar heat causing blistering and membrane displacement.
Wind uplift damage
Exposed windward edge is at the highest risk. Incorrect wind load calculations can result in detachment of the membranes.
Deck deflection
Structural instability of the deck can restrict effective drainage. Any water ingress will weaken the structure below.
System failure
Cracks in the aged asphalt allow water to enter the roof system and in to the building below.
Lack of maintenance
Lack of regular maintenance fails to pick up on damage that could easily be rectified before water ingress is an issue.