Metal Roof Over Asphalt Shingles: Benefits and Considerations

Installing a metal roof over asphalt shingles can be a cost-effective way to upgrade your home's exterior. This process is known as a "metal roof over" or "overlay" installation.

A key benefit of this approach is that it can extend the lifespan of your existing roof by 20 to 30 years, according to the National Roofing Contractors Association (NRCA). This is because metal roofs are more durable and resistant to weathering than asphalt shingles.

However, it's essential to consider the weight of the metal roof, which can add up to 4 pounds per square foot to the existing roof structure. This can put additional stress on the roof's framing and potentially lead to costly repairs down the line.

In some cases, a metal roof over asphalt shingles can also improve your home's energy efficiency by reducing heat transfer and air leakage.

Related reading: Asphalt Shingles Cost per Square

Before installing a metal roof over asphalt shingles, it's essential to prepare the surface properly. This involves addressing any existing roof leaks and replacing rotten rafters or sheeting.

You'll also want to look out for signs of the previous roof weighing too much, such as buckling trusses or sagging decking. This will ensure a stable surface for the new metal roof.

To install metal roofing over shingles, you can choose from two methods. The first is to apply an approved underlayment over the old shingles, which is the fastest way to install. However, it doesn't provide the flattest surface for metal roofing installation. The second way is to install 1×4 purlins over the shingles, which is more expensive but will also be higher quality.

Here are the essential steps to prepare the surface:

By following these steps, you'll be able to ensure a durable and aesthetically pleasing metal roof over your asphalt shingles.

If you're considering installing an overlay, there are some crucial things to keep in mind. An overlay can only be done once, so if you've already had one, it's not an option.

Your existing asphalt shingle roof needs to be in good condition and unblemished. This means no missing or damaged shingles, and no signs of wear and tear.

There are only a few instances where an overlay makes sense: your existing roof has only one or two layers of old roofing, and the structure of your roof is solid enough to anchor the new metal shingle roofing.

Here are some key factors to consider:

An overlay may not be the best choice if your existing roof has multiple layers, as this can increase the cost of a future roof replacement due to the removal of extra layers.

To start the installation process, you'll want to measure your roof accurately to determine how many metal panels you'll need. This will ensure a smooth and efficient installation.

First, install a layer of underlayment over your existing shingles for added protection. This is especially important if you have asphalt shingles, as the underlayment will help prevent the granules from running up against the new metal roof and causing damage.

Worth a look: Cost of Steel Shingles vs Asphalt

You'll also want to check with your local building department to ensure that installing a metal roof over shingles is allowed in your area. Some areas may have specific regulations or restrictions, so it's always a good idea to double-check.

Before installing the metal roof, make sure to address any existing roof leaks and replace rotten rafters or sheeting. This will ensure a solid foundation for the new roof.

Here are some key steps to follow during the installation process:

Remember to use synthetic underlayment, which will not tear when the metal roof expands and contracts. This will provide a more durable and long-lasting installation.

Metal roofs over asphalt shingles offer a range of benefits, from energy efficiency to curb appeal. By installing a metal roof over shingles, you can save in labor costs and prevent the old shingles from being thrown into landfills.

Metal roofs can last for around 40-70 years, depending on the material, which is significantly longer than traditional asphalt shingles. They can withstand severe weather conditions, including wind gusts up to 140 mph and hail storms.

Broaden your view: Asphalt Driveway

Installing a metal roof over shingles can improve your home's energy efficiency by reflecting solar radiant heat, which may even reduce cooling costs by 10-25%. This is especially valuable during hot summers.

Metal roofs come in a wide variety of colors and finishes, including the appearances of natural cedar shakes or stone. They can also provide an extra layer of insulation, helping to further insulate your home.

Here are some of the key benefits of metal roofs over shingles:

Proper preparation and cleaning of your existing asphalt shingles is crucial before installing a metal roof. This involves assessing the condition of your shingles, removing any loose debris, and patching up minor holes or imperfections.

You may need to use a long-handled broom to remove loose debris, followed by patching up any minor holes or imperfections in the shingles. It's also advisable to use a roofing underlayment over the shingles to provide an extra layer of protection and a smoother surface for your metal roof.

Related reading: Architectural Shingle Installation

Experts from the cleaning industry suggest that a clean surface is essential for a secure metal roofing installation. Dust, dirt, and other debris can hinder adhesion, making the roof less stable. So before you install, it might be a good idea to employ professional cleaning services for an exceptionally clean surface.

Here are some key things to keep in mind when preparing your existing shingles:

Regular cleaning post-installation is also vital to extend the life of your new metal roof. Dirt, tree sap, and even bird droppings can corrode metal over time. Cleaning professionals recommend routine cleaning with appropriate solutions to ensure the longevity of your metal roof.

Preparing the surface for a metal roof installation is a crucial step that requires attention to detail. You'll want to assess the condition of your existing shingles, as more than 20% of damaged shingles can compromise the effectiveness of your new metal roof.

To prepare the surface, you may need to use a long-handled broom to remove loose debris, followed by patching up any minor holes or imperfections in the shingles. It's also advisable to use a roofing underlayment over the shingles to provide an extra layer of protection and a smoother surface for your metal roof.

Before installing a metal roof over shingles, make sure to address any existing roof leaks and replace rotten rafters or sheeting. This will ensure a stable and secure surface for your new metal roof.

Here are some key steps to keep in mind when preparing the surface:

By following these steps, you'll be able to create a stable and secure surface for your new metal roof, ensuring a successful and long-lasting installation.

Safety Considerations are crucial when preparing for a metal roofing installation. This process can be hazardous, so proper gear and guidelines must be followed.

Always wear protective eyewear and gloves to shield yourself from debris and sharp objects. Safety glasses can protect your eyes from flying shingles or metal fragments.

Ladders and scaffolding are often necessary for metal roofing installation, but they can be unstable. Make sure to secure ladders and scaffolding to prevent accidents.

Never work on a ladder or scaffolding alone; having a spotter is essential for your safety. This extra pair of hands can help prevent accidents and provide assistance if needed.

Metal roofing installation requires a level surface, but shingles can make the surface uneven. Remove shingles carefully to create a smooth surface for metal roofing installation.

Adding insulation to your roof is a crucial step in preparation for a metal roof installation. E-foil insulation can be added to the top of the underlayment to provide a protective surface between the old asphalt roof and the metal roof.

This layer can also increase energy efficiency by reflecting heat away from the roof in the summer.

Metal roofing is very lightweight, making it easy to install over the top of shingles.

This can be a major advantage when preparing for a new roof installation, especially if you're looking to minimize structural damage and disruption to your home.

The lightweight nature of metal roofing also means that it requires less material and labor to install compared to other types of roofing materials.

This can lead to significant cost savings and a faster installation process.

If this caught your attention, see: How to Install Rain Gutters with Metal Roof

Before you start preparing and cleaning your roof for a metal installation, you need to know what can be used. Copper is a great option, known for being long-lasting and soft.

Aluminum is another durable choice, resistant to damage from saltwater. Its durability is a major plus, especially if you live in a coastal area.

Zinc is incredibly durable and long-lasting, with a low melting point to boot. This makes it a great option for areas with high temperatures.

Steel is one of the most durable and long-lasting options available, coming in variations of galvanized, Galvalume, and weathering.

Condensation is a major concern when it comes to metal roofs. Steel will condensate if there's any air space underneath it, no matter how small the gap.

You can prevent this by laying the metal roof directly on a vapor barrier. This ensures that the metal is in direct contact with the barrier, eliminating any air space.

Leaving the shingles on or using felt paper during new construction can help with this process.

Installing a metal roof over an existing shingle roof can save you a lot of money in the long run. This is because metal roofing lasts decades longer than an asphalt roof, making it a more cost-effective option.

While it's cheaper to purchase shingles upfront, metal roofing provides better value in the long-term. A metal roof can last for decades, and with proper installation, you'll likely never have to purchase another roof again in your lifetime.

For another approach, see: Roofing a Gambrel Roof Shed

You'll need to factor in the cost of hiring a contractor to remove the existing shingle roof, which can be a significant expense. However, the cost of metal roofing is usually recouped over time due to its extended lifespan.

Metal roofing costs more than asphalt shingles upfront, but it's a worthwhile investment if you plan to stay in your home for an extended period.

Installing a metal roof over asphalt shingles can be a bit more complicated than a straightforward installation. The cost of metal roofs can be much higher than shingles, making it a significant expense for many homeowners.

One of the main drawbacks of installing a metal roof over shingles is the increased cost. Metal roofs can be up to several times more expensive than shingles, which can be a major barrier for many homeowners.

Metal roofs can also be noisy during rain and hail, which can be a drawback for some people. A layer of soundproof insulation can help mitigate this issue, but it adds to the overall cost.

The cost of metal roofs can be a significant investment, but it's worth considering the long-term benefits, including increased durability and value.