When deciding between overlay and tear-off for a green roof, it’s important to understand both options clearly. An overlay involves installing a new layer of roofing over the existing one, saving time and reducing waste. This can be suitable if the current roof is still in good shape, with no signs of water damage, rot, or structural issues. The overlay must be done carefully to ensure proper drainage and support for the green roof system, as the added weight can exacerbate hidden problems. To assess if an overlay is feasible, homeowners can safely inspect their roof for visible damage, soft spots, or active leaks. Checking the attic for moisture or discoloration can also provide clues about the underlying roof condition. If everything seems sound, an overlay can be a cost-effective, less disruptive option, but it may slightly reduce the lifespan of the new roofing since it sits atop an older layer.
On the other hand, a tear-off involves removing the existing roofing layers down to the roof deck, providing a fresh start and the opportunity to address any underlying damage or upgrades in insulation and waterproofing, which are critical for green roofs. This method is usually necessary if the existing roof is old, damaged, or not suited to support the green roof’s weight and complexity. While more labor-intensive and costly, it often ensures a longer-lasting, more reliable roofing system with better warranty coverage. When speaking with a roofing contractor, it’s wise to ask, “How will you ensure the roof deck is sound before installing the green roof?” and “What warranty coverage applies if we overlay versus tear off?” These questions help clarify risks and protections, supporting an informed decision that aligns with both budget and long-term roof health.