Shingle roofing means stripping old courses down to the deck, replacing rotted plywood sheathing, and rebuilding from the ice-and-water shield up. On a 1950s Colonial or ranch, we usually tear off rather than overlay, since a second layer hides soft decking.
Architectural shingle and laminated products like GAF Timberline HDZ or Owens Corning Duration hold up better against salt air and wind-driven rain than the old three-tab shingle did. They carry higher wind ratings, resist algae streaking, and carry manufacturer warranties.
A good system keeps water out of the eave, the valley, and the chimney flashing, which is where most leaks start. Adding ridge vent and soffit vent keeps the attic cooler, cuts summer cooling bills, and stops the heat that bakes shingles from underneath.
