PORTLAND, Ore.—In the U.S. and Canada, homeowners are gearing up for spring and summer exterior home improvement projects, including re-roofing their homes.
This is also a time when a massive amount of waste is created, due to the removal and disposal of old asphalt roof shingles. As the most common type of roofing material, approximately 11 million tons of worn-out asphalt shingle roofing waste is dumped into the landfill every year, representing a whopping eight percent of the total building-related waste stream in the United States.
To help reduce the environmental impact and save on re-roofing labor costs, experts say the fact is an old asphalt roof doesn’t necessarily have to be torn off and removed in order to install a new roof. Thanks to its lighter weight, metal is one of the only roofing materials that can be installed directly over asphalt. The benefits of doing so not only include preventing waste, but realizing the savings that comes from reduced labor and tear-off costs and increased long-term energy efficiency.
According to the Metal Roofing Alliance (MRA), the leading nonprofit trade organization representing the industry, it’s the lower weight and greater resiliency of metal roofing material (50 lbs. per 100 square feet for aluminum and 80-100 lbs. for steel, as compared to nearly 275-425 lbs. per 100 square feet for asphalt) that makes it suitable for installing over asphalt without adding too much weight for a home’s structure. It also increases insulation properties, helping homeowners save on heating and cooling costs.
“Every year, we receive questions from homeowners who are rightly concerned about all the waste and mess that comes from removing their old asphalt roofs, asking if they can install longer lasting metal over their existing roofs to help reduce waste and avoid having to re-roof again in the future,” said Renee Ramey, MRA executive director. “In many cases, the answer is yes, and there are plenty of great reasons for doing so.”
Warranties offered on quality metal roofing systems installed over asphalt shingles are not typically impacted as long as the roof is properly installed, which is not the case when it comes to installing a second layer of asphalt over the top of an old shingle roof. That’s because heat gain can impact the integrity of asphalt shingles and cause the new second layer of roofing to deteriorate much faster, while high temperatures will not impact quality metal roofing systems or finishes.
Other factors and considerations for installing a new metal roof over asphalt include:
“For a homeowner, leaving their old shingles in place can actually make the home more energy efficient and resilient,” said Todd Miller, president of Isaiah Industries, an MRA member and well-known industry expert. “But perhaps more importantly, it means they can use the money they save on old roof removal and disposal to invest in an upgraded metal roof for their home. Sometimes, those savings allow them to buy the better roof they really want.”
