When people seal their driveway or parking lot they (in most cases) do it to make the asphalt look new again or go over new and old asphalt in the case where there has be a repair done to make the area look uniform again. Lastly they will seal a lot to hide all the existing line painting then paint new lines in a new configuration.
Things that you should know:
Sealing in the spring time makes your lot/drive way look great for the spring and summer and
into the fall but if you seal in the fall time the sealer fills in all the small micro cracks which will
prevent water from entering through the asphalt in the winter time. As water freezes and
thaws through the winter it will open up crack in your asphalt allowing water to penetrate into
the gravel layer below your pavement and this in turn will break up your asphalt.
When asphalt areas have become “Alligatored” (Cracked up so much it looks like the skin of an
alligator) this condition should be repaired A.S.A.P. If not the vehicles passing over this area
(Especially during the freeze / thaw months of late winter / early spring or during the rainy
seasons. The vehicles will create a pumping action, fines, clay from the ground sub base soil will
be pumped up through the gravel layers thus contaminating your stone base. When this occurs
the repair work will be more costly as you will not only have to replace the asphalt on the
surface but the stone base as well.