No, you don't have to seal your driveway after pressure washing it. However, if you want to seal it, there are a few things you should know. Sealing your driveway with a sealant will protect it from staining and fading, but it won't make it waterproof. It's also important to choose the right sealant for your type of pavement. Asphalt driveways should be sealed with an asphalt-based sealant, while concrete driveways should be sealed with a concrete-based sealant.

It depends on the type of sealant that you use. If you use a penetrating sealer, then you do not need to apply a top coat. But if you use a non-penetrating sealer, then you should apply a top coat. Penetrating sealers soak down into the surface and fill in the pores and voids. This leaves a water resistant barrier on the surface that will protect it from weathering and staining. Non-penetrating sealers form a film on the surface of the driveway that is not water resistant. So if it rains after you have applied a non-penetrating sealer, the rain will wash away the sealer and your driveway will be unprotected.