Should I Remove Existing Shingles?

When replacing a roof, homeowners sometimes get conflicting advice about whether to remove the old shingles or to install a new layer on top.

It can be tempting to cut corners and try to reduce labor costs by avoiding the tear-off, but you should definitely talk to a professional roofer first, because the decision depends on several factors and you don't want to make an expensive mistake.

Most asphalt shingles have a lifespan ranging from ten to thirty years, depending on the quality of material (some luxury shingles offer 40- or 50-year warranties). While it is not uncommon for someone to lay a new roof over an existing shingles, here are some things to consider:

  • Building codes in some locales prohibit laying a 3rd layer on top of two existing layers. Check with your roofer or your local building codes office for specific requirements in your area.
  • The existing layer should be thoroughly inspected before a decision is made --- if the top layer is cracked, wrinkled, buckled or damaged in any way, the new layer won't lay flat and most reputable roofers are not going to want the potential liability. You also need to look at the shingle manufacturer's warranty to make sure your warranty isn't voided by laying new shingles on top of existing ones.
  • Added weight is also a factor -- can your roof structure support the added weight? A square of shingles (covering 100 square feet) weighs between 250 and 450 pounds depending on quality of material. A 2000sf roof, for example, would require at least 20 squares, placing 5,000 to 10,000 pounds of additional weight on your structure.