Dry spots on Flat Roof

Hi everyone,

I have a new insulated roof on my garage and dining room extension. When it is drying after a rain shower or in the morning it always has some dry spot about 3 inches in diameter which appear first.

I assume that this is where insulation has been nailed in place. Can someone please advise me if this is normal for an insulated flat roof or if my roofer has done something wrong?
Thanks,
Slangivar

I assume that the `spots' are fairly evenly spaced across the roof.

The insulation may be fixed with a tube washer or pressure plate thus causing a `very' slightly raised area, being higher than the surrounding field area, albeit by a small amount, this area will show as dry a little earlier than the rest, if it's a pressure plate rather than a tube washer it will also dry slightly quicker as the surface will heat a little quicker.

It is perfectly normal to fix the insulation that way rather then bonding it to the VCL so unless the flat roof fails I can't see that you should have any issue

Thanks, Would the spots be visibly higher than the surrounding area if that was the case?