roofoverroof

Roofoverroof, commonly referred to as roof-over-roof or roof overlay, is a roofing practice in which a new layer of roofing material is installed directly over an existing roof rather than removing the old covering. It is most often used with asphalt shingle systems and is typically allowed only when one existing layer of shingles remains and the underlying structure is sound.

The primary advantages of a roofoverroof include lower immediate cost, faster installation, reduced waste, and temporary extension of service life. It can be appealing when the existing roof shows wear but has no significant rot, leaks, or structural deformation. The process generally involves inspection, minor repairs to decking and flashing, installation of underlayment or asphalt-based adhesives where appropriate, and application of new shingles.

Drawbacks include added weight on the roof structure, potential trapping of moisture or rot that was hidden by the old layer, reduced ability to assess and repair decking and flashing, and typically a shorter warranty than a full tear-off replacement. Building codes and manufacturer warranties often restrict overlays; some jurisdictions prohibit multiple layers or require a complete tear-off if more than one layer exists.

Alternatives to roofoverroof include full tear-off and replacement, which allows full inspection of the deck and flashing and generally yields a longer-lasting roof. The decision between overlay and replacement depends on structural condition, long-term plans, local regulations, and budget.