Re-Roofing Versus Roof Replacements

Category: Roof Maintenance

Is your roof nearing the end of its life? Whether you notice signs of wear in your commercial roof or know it is nearing the end of its warranty, you might be wondering if it’s time for a replacement. If your roof is in good condition, you have the option to re-roof the existing roof rather than tear it off and install a new one. If your roof uses shingles or a protective industrial membrane, you can add a second layer of the material directly on top of the existing roof. You’ll add years to your roof’s life expectancy for a fraction of the cost of a full replacement.

This guide will explain the difference between re-roofing and roof replacements, and help you determine which option will be best for your roof.

What Is Re-Roofing?

Re-roofing is an alternative to completely removing and replacing a roof. When re-roofing is employed, a second layer of shingles is placed on top of an existing roof. While not always possible, re-roofing can help you save on replacement costs. Since the existing roof does not need to be torn off, there’s less labor and time involved. The process is also called recovering since the existing roof is covered with an additional layer.

Another critical benefit of re-roofing is significant savings on materials. To understand just how much you save, consider how many layers comprise your roof.

Flat and low-pitched roofs usually consist of three layers.

Weatherproofing: All roofs need at least one layer of weatherproofing to keep out moisture. Areas in colder regions might also need an ice-protective barrier.
Reinforcement: Another layer adds durability, puncture-resistance and structural stability to the roof.
Surfacing: A top layer protects the two bottom layers from the weather and sun. The surfacing can add additional benefits, such as fireproofing or energy-efficient solar reflective coatings.

A commercial pitched roof typically consists of four layers.

Decking: Also called sheathing, this bottom layer of the roof is usually a panel of plywood that acts as a foundation for the roof.
Ice and water barrier: Self-sealing and waterproof, the ice and water membrane protects your building from water penetration and ice build-up.
Underlayment: A uniform layer of felt protects against water infiltration under the shingles, and allows the shingles to lay flatter.
Shingles: Asphalt shingles, metal panels or wood shakes are the recognizable outer layer of your roof. They provide architectural aesthetics as well as protection. Asphalt shingles will also have a fifth layer, called a ridge cap. The ridge cap is an extra-long shingle that fits over the vertices of the roof.

The factor that makes re-roofing cost-effective is that most of the layers of the roof stay intact. You do not invest in a whole new roof. Instead, you rely on its existing layers to provide structure and protection for your building. Re-roofing offers significant cost savings since you are reusing these materials. It also keeps your building protected during the roof installation process, since these protective layers stay intact.

Since roofs have many layers, it is difficult to inspect them during the recovering process. If there’s any underlying damage to these layers, a re-roofing will not resolve the issue. Tearing out the shingles and the other protective barriers of the roof allow for the installation of new materials that will last for years to come.

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What Is a Roof Replacement?

Recovering the existing roof is sometimes not possible. If a roof already has a second layer, you cannot add a third layer. The 2018 International Building Code (IBC) 1511.3.1.1 prohibits re-roofing when the existing roof has two or more applications of any roof covering. A roofer cannot recover a clay, slate, cement or asbestos-cement roof. Re-roofing is not possible when the current roof is water-soaked or has significant structural damage. If an inspection reveals the roof has compromised integrity, you should opt for a roof replacement instead.

Unlike re-roofing, a roof replacement tears out the existing roof and replaces it. The waterproofing and underlayment layers are removed and replaced with new material. Tearing out the shingles and underlayment lets roofers inspect the decking. If the decking is intact, new water barriers, underlayment and shingles are applied. If the decking has damage, it will be repaired before the new roof is installed.

A roof replacement is always possible and recommended in any case where a roof has more than a few small issues. Rather than covering up the damage, a new roof gives you structurally-sound, long-lasting handiwork. A new roof also comes with a warranty. Depending on the materials used, it will last between 10 and 50 years. A roof replacement doesn’t have the same material restrictions as recovering, so you gain flexibility.

A roof replacement is a significant investment. It costs more in labor, materials and time than re-roofing. With new materials, your building will have added protection and longer-lasting materials. You don’t have to question whether your roof is sound, because any issues are dealt with during replacement.

How Often Should You Replace Your Roof?

How many years your roof is designed to last depends on the type of roof you have. On an industrial flat roof, the roofing system protective layers you use can impact its lifespan. The materials used on a pitched roof will also have a different life expectancy. Weather damage, frequency of maintenance, slope and mistakes in installation can all influence how long your roof lasts.

Here’s how long your industrial roof can last, depending on the materials used:

Thermoplastic polyolefin (TPO): A type of single-ply roof membrane, TPO is popular for low-slope roofs. It’s a material known for high durability and extreme weather resistance. Protections from heat aging and UV degradation contribute even further to its longevity. The typical life expectancy is 22 to 30 years.
Ethylene Propylene Diene Monome (EPDM): An EPDM roofing system features a rubber membrane, which increases longevity. The rubber layer is durable and resistant to impacts, sun and heat damage. It can be installed over an existing roof, so it’s ideal for re-roofing. Rubber roofs are known to last between 22 and 35 years.
Polyvinyl chloride (PVC): Like TPO, a PVC roof is another kind of single-ply white protective roofing layer. It’s an energy-efficient roofing option since the color retains less heat. It’s also a fire-retardant material, known for its self-extinguishing abilities. While PVC roofs can last between 20 and 30 years, their life expectancy can increase due to the decreased effects of fire damage.
Metal roofing systems or metal paneling: Metal roofs withstand water and air penetration. Metal roofs are easily retrofitted over an existing roof. They need little maintenance and can prolong the life of your roof. They can last between 30 and 45 years.
Asphalt roofing systems: Modified bitumen and built-up roofs both use asphalt as an adhesive. Slopped roofs often use asphalt shingles, which have a long lifespan with proper maintenance. An asphalt roof can last anywhere between 20 and 40 years.

While a material’s projected lifespan is a critical factor in determining when it’s time for a replacement, there are lots of other signs. While a roof that leaks in a few spots can be fixed with a roof recovering, significant damage means it is time to replace the roof. Here are some signs of damage to look for:

Leaking or water damage
Missing shingles
Sagging in the roof deck
Visible holes
Dark spots
Mold, rot or moisture

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When Is Re-Roofing a Good Idea?

There are many circumstances where re-roofing can be a cost-saving solution. An ideal candidate for re-roofing is a roof that is nearing the end of its lifespan but is still in great shape. A roof under 15 years old with a minor issue in one area might be better off with a repair than a total recovering. Re-roofing only part of a roof will look uneven.

If a roof is 15 years or older and starting to see signs of minor wear, it’s possible re-roofing will be a helpful solution. If you find granules from asphalt shingles in the gutters, a new layer could be the perfect solution. A few minor leaks or issues can also be resolved with a recovering. Both pitched and flat roofs should not have more than one roofing application. So, if the roof has not been re-roofed before, it is also a strong contender.

Before you can be certain re-roofing is a good idea, you should have an experienced roofer check it. A licensed roofing contractor will need to walk on the roof and inspect the construction. Even a seasoned professional cannot approve a re-roofing job from the ground. By peeling back some of the shingles, a professional can see if there are already two layers. The inspector will also walk around to see if the roof feels soft underfoot and look for deterioration in the flashing.

Re-Roofing Versus Roof Replacement — What’s the Right Choice for You?

Deciding whether to re-roof or replace your roof starts with a roof inspection. While you can choose to replace a roof by inspecting it from the ground, you cannot make a safe decision to re-roof without examining the construction closely. When you have the roof replaced, all the material is torn off and inspected on-the-job. A decision about whether to replace the decking can be made after examining it first hand. The inspection will require a roofing professional to walk on the roof and feel for damage on foot.

Before you decide to have a roof inspected for re-roofing, you must answer several questions about your roof.

How Many Layers Are on the Roof?

Depending on the material used in your commercial building roof, you have a limit on how many layers your roof can have. A metal roof can be retrofitted onto an existing roof as the second layer. If the original construction of the roof is metal, you cannot safely add a second layer. A roof with asphalt shingles can withstand two layers before total replacement becomes necessary. Flat roofs with either an EPDM or TPO membrane can be re-roofed with one additional layer. If your roof has already been re-roofed or is a metal roof, you can rule out re-roofing as an option.

Is the Existing Roof Smooth?

An issue that arises particularly with asphalt shingles is the surface becoming uneven over time. Shingles can start to curl or loosen with time. If a roof is missing shingles or has significant portions of curled shingles, recovering the roof will not be possible. Putting new shingles over old ones requires a flat, even surface. Covering an uneven roof with a fresh surface material will look unprofessional. It also has more potential for water leakage and other problems.

Are You Experiencing Any Leaks, Ice Dams or Condensation Issues?

While a few small leaks can be patched up during a re-roofing, anything more significant warrants replacement. Re-roofing only replaces the outer layer of the roof. It cannot repair damaged underlayment or weatherstripping.

On a pitched roof, an ice dam can be another sign of damage to the roof’s weatherstripping. As ice builds up on the outer lip of the roof, it prevents water from draining away. Weatherstripping creates an insulating layer between your heated home and the frigid outdoors. By preventing warm air from escaping, weatherstripping allows snow to flow evenly. If a roof is showing signs of ice build-up around the outer edges of the slope, it’s a sign the insulating ice barrier is damaged.

Leaking and ice dams are both signs that a roof needs a full replacement rather than re-roofing. Even if there are no leaks, excessive condensation in the attic of the building can be another sign of excess moisture penetrating your roof.

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What Is the Expected Lifespan of Your Roof?

It can be helpful to think of re-roofing as a way to increase the lifespan of your roof. Retrofitting metal panels onto an existing roof can add 20 years to the roof’s lifespan. The best time to choose re-roofing is when your roof is nearing the end of its lifespan before it starts to degrade. So, if you’re nearing the end of that life expectancy, it’s a great time to re-roof.

If your roof is well within its life expectancy and starting to show signs of damage, a roof replacement is probably necessary. The good news is that your roof should still be covered under warranty. Most shingle and industrial roofing manufacturers guarantee their products for a length of time. If the manufacturer has certified the contractor who installed the material, you can likely have your roof replaced under warranty.

Discover Professional Roofing Solutions From Houck

At Houck, we specialize in specialty restoration and preservation projects. Our roofing maintenance and repair services cover a variety of challenging roofing jobs. Whether your commercial building has a steep slope or a flat roof, we can provide the expertise and quality you need to extend the life of your roof. We can help you determine if you need a roof replacement or if you can safely re-roof for a longer-lasting exterior. We also provide custom metal roofing systems, coatings and preventative maintenance services. Houck is your choice, from floor to roof.

Dial 800-458-2122 or contact us online to speak to a Houck roofing expert, and see how we can get to work for you.