can you put a metal roof over 2 layers of shingles

Can you put metal roofing over asphalt shingles?

Homeowners looking to replace an aging roof have two basic options: they can either strip off the old roof and replace it with a new asphalt roof, or they can install metal roofing over the existing asphalt shingles. Unless building codes require it, there is usually no need to tear off the old roof.

Can you re-roof over two layers of shingles?

Other areas will allow you to re-roof over two layers. In most cases it’s not even an issue if you are only going over one layer of shingles.

Should you cover your roof with metal sheets?

When there are multiple layers of shingles, the trusses can have too much weight, putting the homeowners at risk of the tresses falling, damaging the roof. The condition of your existing roof is also crucial to consider. Covering the area with metal sheets without repairing the damage can lead to more significant problems.

Can You double shingle a roof?

Many roof shingle manufacturers will cancel any shingle warranty in double roof installation. According to many shingles manufacturers, most contracts do not validate when a new layer of shingles is layered on top of existing roofing. A double layer of shingles traps more heat, damaging the shingles, thus shortening their lifespan and the roofs.

How many layers of shingles can you have under a metal roof?

two shingle layersOne to two shingle layers can rest safely and securely under a metal roof. Any more than two layers could reduce the stability of your roof. Many building safety codes will not allow more than two layers, so check your local areas before making an installation.

Can you put metal roof over shingles without furring strips?

It is not recommended to install metal roofing over shingles without furring strips. The thermal expansion and contraction of the metal will rub against the shingle granules and the metal will corrode from the underside. The gaps introduced by furring strips also allow air venting which can reduce moisture.

Can you put metal roof right on top of shingles?

In almost every case, the answer is yes, you can lay down a new metal roof over an existing shingle roof. This is one of the many reasons metal roofs keep growing in popularity – their installation doesn't require completely tearing off the existing roof, which is a time-consuming and expensive job.

Do I need underlayment for metal roof over shingles?

If your metal roof is to be installed over solid decking or over existing shingles (an environmental benefit), a layer of quality underlayment between the two is essential.

Does metal roof need ventilation?

We say yes. Like other types of roofing, metal roofing needs to breathe. Metal roofs use static ventilation, which promotes natural airflow. In other words, it doesn't need to rely on fans or other methods to allow for proper air movement.

Will a metal roof cause mold?

Typically, metal roofs should not cause mold. However, often, many contractors and roofing companies cut corners to save time and money. Unfortunately, the result is a no moisture barrier, causing a build-up of mold and rust.

Is it better to remove shingles before installing metal roof?

Metal roofs can be installed over your existing roof without tearing off shingles, provided local building codes allow it. While shingle removal is the preferred route, tear-off is messy and raises the cost of the job. A potential problem with this type of installation is trapped water vapor.

Do metal roofs leak more than shingles?

Do Metal Roofs Leak More Than Shingles? If installed incorrectly, metal roofs have the potential to leak more than shingles. However, if you find an experienced contractor who can install it correctly, metal roofs shed snow and ice to prevent moisture buildup.

What do you put between shingles and metal roofing?

Install Synthetic Underlayment Installing underlayment will help to keep the asphalt shingle granules from running up against the new metal roof, which could cause damage over time.

Do you need an air gap under a metal roof?

Research has confirmed that creating an air space under a metal roofing system will increase energy savings during both summer and winter months. A study was funded by the U.S. Department of Energy and conducted by the Oak Ridge National Laboratory to document energy savings of metal versus asphalt roofs.

Does a metal roof need a vapor BArrier?

Without one, water can get trapped in the wall, which will produce moisture and ultimately other issues like rot, mold, and trouble with thermal performance. Vapor barriers are recommended for under metal roofs.

How much does it cost to put a metal roof over shingles?

The total job can average between $1,000 to $1500. The price can increase based on the complexity of the workload. Having the removal and disposal of an old roof factored into the overall costs is helpful when gathering estimates.

What is the purpose of furring strips on metal roof?

Furring strips bolster insulation to prevent condensation. It's not ideal to install a metal roof over shingles without furring strips.

Can you put metal roofing directly on rafters?

Can you put metal roofing directly on rafters? Yes, a metal roof can be installed directly over rafters. Since corrugated metal panels are relatively lightweight, they can fit almost any type of situation.

What do you put down under metal roofing?

The traditional and most common material used for roof underlayment on a steep-slope metal roof is non-perforated, asphalt-impregnated felt underlayment. There are several types of felt underlayment including both organic reinforced and inorganic reinforced.

What are the pros and cons of putting metal roof over shingles?

Installing Metal Roof Over Shingles Pros And ConsYou'll save on labor costs. ... Added insulation protection to your home by having extra roofing layers.Faster installation as less labor is required.Eco-friendly because the old asphalt shingles will not have to be thrown away.

How long does a metal roof last?

Longer Lifespan. Compared to the shingle roof, once you install a metal roof, it will last nearly a lifetime, with a longevity of 40 to 70 years of use. Shingled roofs have a shorter lifespan of 12 to 20 years, which means it'll need replacing several times within the same timeframe. Nearly Indestructible.

What happens when moisture builds up between shingles?

When moisture starts to build up between a metal roof and shingles, you can end up with rot, mildew, or mold growth. With continued exposure, rotting can cause the wood structure to weaken. You may end up having to tear off the metal roof, the old shingles, and replace crucial parts of the home's structure.

How to make metal roof less loud?

There are ways to ensure metal roofs don't make any more noise than other roofing types. Adding a roof deck, insulation, and underlayment will help dampen any noise. Without all of these elements, a metal roof will be close to deafening.

What is underlayment on metal roofing?

While shingles will work as a second layer to prevent moisture and reduce noise, the abrasions from the shingles expanding and contrasting can cause damage to the metal. An underlayment such as felt prevents damage to the metal roofing.

How much does metal weigh per square foot?

But metal weighs less than one pound per square foot, so it doesn't add an excessive amount of weight. Roofs with too much weight can sustain structural damage. The lightweight of metal allows it to go over the top of shingles to save you money, time, while not affecting the max weight capacity of your roof.

Why do shingles rub against metal?

Shingles have a rough texture, which can rub against metal and cause it to lose its protective coating. As the metal wears down, it can be more susceptible to corrosion, thinning, and scratches, reducing the roof's lifespan. An underlayment placed between the layer of shingles and metal can prevent these issues.

Can you put a flat roof over a metal roof?

Flat roofs with zero pitch are not suitable for metal roofs because there's no way for the water to drain off when it rains. Standing water can lead to rusting and compromised structural integrity. For you to install metal over shingles, flat roofs must have a low pitch at minimum.

What is underlayment on shingles?

A layer of underlayment installed on top of the existing shingles will help keep the granules of the old shingles from rubbing against the back of the metal and causing possible corrosion. The industry standard for underlayment is often thought of as felt paper (tar paper) but there are also many newer synthetic underlayments ...

How much does a metal roof weigh?

Metal roofing weighs less than one pound per square foot. Asphalt shingles can weigh up to four pounds per square foot depending on the brand. If you don’t want to take our word for it check with your local building department. In some areas building officials only allow a re-roof over one layer of shingles.

What to do if your roof leaks?

If there are any existing roof leaks, you need to address them and replace any rotten sheeting or rafters. If there are any signs of problems caused from the previous roofing weighing too much, they must also be addressed. This could include things like sagging decking or buckling trusses.

Can you re-roof over one layer of shingles?

In some areas building officials only allow a re-roof over one layer of shingles. Other areas will allow you to re-roof over two layers. In most cases it’s not even an issue if you are only going over one layer of shingles.

Can I install a new metal roof over shingles?

The answer is: “ Yes you can. ” And by doing so, you save in the labor and hassle of tearing off the old roof and you won’t be contributing to filling our landfills. Another added benefit is that the layers of your old roof will further insulate your home. Metal is the best choice due to its very low weight per square foot and its unique design. Metal roofing weighs less than one pound per square foot. Asphalt shingles can weigh up to four pounds per square foot depending on the brand.

What is the best way to install a metal roof?

You have two basic options when it comes to installing a metal roof: 1 Stone-coated or painted shingles (also known as “pre-formed crimped”); 2 Standing seam solutions.

How are metal shingles made?

Metal shingles can be made using a specific color, shape and length , and there are many attractive options for homeowners. That’s because they are produced by taking large flat rolls of colored metal stock and then shaping it with a large machine.

How long does a metal roof last?

Metal roofing is expensive, but it lasts a lifetime. For homeowners who want the very best protection against wind, snow and rain, this might be the best possible solution from a return on investment (ROI) perspective. For a larger upfront cost, you will have metal roof that might last 50 years.

What is the most expensive metal roofing solution?

In terms of labor costs, the most expensive option is the standing seam metal solution , which is due to the professional expertise required. In terms of materials, the most affordable option is the painted metal shingles.

What is a standing seam shingle?

Stone-coated or painted shingles (also known as “pre-formed crimped”); Standing seam solutions. With the first option, you place small panels in horizontal rows, giving them the appearance of traditional shingles. With the second option, long, single panels run vertically all the way from eave to ridge.

How fast can a metal shingle withstand?

In general, metal shingle systems (both stone-coated and painted) can withstand winds of up to 120 miles per hour. In contrast, standing metal seam solutions can only withstand winds up to 80 miles per hour.

What metal is used for a roof?

The metal used for the roof can be tin, copper, aluminum or steel. In terms of performance many homeowners choose a steel roof, making it the most popular option when it comes to creating a metal roof over existing shingles. When choosing to install a metal roof, homeowners need to take into account several trade-offs involving cost and performance.

Step 1: Inspect the Roof

The first step is to inspect your existing roof. If it has just a single layer of asphalt shingles, it’s a good candidate for a new layer of metal roofing. If there are two layers, you’ll have to strip off all the shingles, repair any holes, and cover the roof with heavyweight tar paper before attaching the metal roofing.

Step 2: Prepping the Roof

All the existing vents, roof jacks, and edge trim must be removed from the roof. If you have attached gutters you’ll need to carefully inspect them and determine if you can leave them in place or if they must be removed and reattached with the new metal roof.

Step 3: Install New Bottom Roof Edge

The new bottom roof edge must be installed before the metal roofing to allow the natural flow of water off the roof.

Step 4: Laying Down the Metal

Set the first piece of metal exactly on the leeward side of your roof. Some applicators lay the metal so the seams cover each other away from the primary view of people on the ground. That’s good for aesthetics, but if you live in a windy area, you should lay the metal so the wind blows over the covering seam, rather than into it.

Note

When you come to an opening for a vent or jack you’ll have to measure and cut the exact location of that opening in the metal roof panel about to cover it.

Step 5: Attach Covering Panel

Once the panels are completely screwed in with 1 5/8” self-tapping sheet metal screws, it’s time to just zip-screw to attach the covering panel at the seam over the lower panel. The zip screws are shorter and should be placed every 36 inches along the seam.

Step 6: Sealing the Vents

Another important step is to seal every vent with a layer of acrylic silicon. Spread it out with a caulking gun, then carefully set the vent or jack and screw it into position.

How Do You Install Metal Roofs Over Shingles?

When installing roofs over shingles, an underlayment is placed over the shingles. This will prevent any leakage onto the existing shingles, though ideally, the roof should already be watertight and in relatively good condition. Once the underlayment is in place over the shingles, the metal roof can be installed. Professionals will ensure that the roof is installed correctly and impervious to water.

How long does a metal roof last?

They’re long-lasting. A metal roof can last up to 50 years or more depending on maintenance, making them exceptionally good investments. They’re easy to maintain.

How to contact Bert Roofing?

Contact the experts at Bert Roofing. Call us at 214-307-8142 or through our website.

Why are metal roofs so popular?

There are a lot of reasons. Metal roofs are beneficial because: They’re fast and easy to install. Rather than having to install a single shingle at a time, workers can install large sheets of metal. They’re attractive and vary in style.

What to do if you can't get asphalt shingles?

If you’re unsure, the best thing to do is contact a professional. They’ll take a look at your existing roof and the material you want to put over it and determine whether it’s the best option.

Why does it take so long to remove an old roof?

Rather, the issue is having to remove the old roof. It takes time to remove an old roof because it has to be stripped down tile by tile. Many people end up putting shingles over shingles — which works just fine for the first couple of times.

Why do you need a metal roof?

Why would you want to install a metal roof over shingle roofs? There are a lot of reasons. Metal roofs are beneficial because: 1 They’re fast and easy to install. Rather than having to install a single shingle at a time, workers can install large sheets of metal. 2 They’re attractive and vary in style. Metal roofs can be fabricated in many styles, even mimicking the look and feel of other luxurious roofing. 3 They’re long-lasting. A metal roof can last up to 50 years or more depending on maintenance, making them exceptionally good investments. 4 They’re easy to maintain. A metal roof does not require a lot of maintenance, though it should be inspected after hail and other weather events. 5 They can be installed over existing roofs. One of the major advantages of a metal roof is that it can be installed over an existing roof.

How much does metal roofing cost?

Metal roofing tends to be expensive, and it’s kind of loud in the rain. Metal roofing can run $120-900 per square foot , which is quite costly. The good news is that it’s extremely durable and you shouldn’t need to replace your roof again any time soon! The other big thing owners notice is that they tend to make noise when it rains, but it shouldn’t be too loud when you’re inside.

Why is metal roofing not a concern?

The main reason this isn’t a giant concern on a single layer of shingles is that metal roofing is usually relatively lightweight. So long as you only have one layer of shingles and your home isn’t super old, this shouldn’t be a huge risk.

What is the best underlayment for a roof?

The most popular underlayment is 30# roofing felt . Some contractors will lay plywood over the battens and then nail the felt to that before installing the roofing. This adds a lot of weight though, so this step is often skipped if the shingles are really thick.

What to do if shingles aren't healthy?

If the shingles aren’t healthy, you’ll have to remove the shingles first.

Why do you need an underlayment?

You should use an underlayment if you want an added safety measure. Underlayment functions as a protective barrier. It absorbs moisture, prevents leaks, and protects the underside of your metal roofing. It’s also fairly inexpensive to have installed as well, so you aren’t losing much by having a contractor add an underlayment even if it isn’t strictly necessary.

Can metal roofing be installed over shingle roof?

If you install metal roofing over a damaged shingle roof, the added weight of the new roof may cause the shingles to weaken and collapse over time.

What to do if metal panels aren't flush?

If the grooves on the metal panels aren’t flush when they’re laid side-by-side, you’ll need to cut them so that the seams match.

Why do you put shingles on top of a roof?

Most roofing contractors may decide to add shingles on top of the existing ones to save the cost. Leaving the old shingles on the roof saves both labor costs and disposal costs. However, leaving the shingles isn’t a good decision both for the homeowner and the home itself in the long run. The disadvantages outweigh the possible advantages by a significant amount. The added shingles on the roof increase the weight and heat absorption, which can destroy the rooftop. Most manufactures do not offer a warranty to double rooftops, and it can become a liability during a home sale.

Why not remove shingles?

A complete tear-off of the roof installation costs about 25% more than installing a roof. The cost is saved, as there will be no labor cost in removing old shingles, and since there will be no or less waste from the cut of new shingles, it will lead to low dumping fees.

Do shingles absorb heat?

Lighter shingles absorb less heat from the sun compared to darker shingles. One of the main features of a shingle is to absorb heat. Additional to another layer of shingle, you will have two alters that constantly absorbing heat. The heat will cause the shingles to deteriorate more rapidly than a roof of a single layer of shingles.

Can you put shingles on a ice dam?

Homeowners who have experienced ice dams or roof leaks know that adding a layer of shingles on the existing shingle roof will not solve the problem. Ice dams primarily form near the eaves where the cold air outside the house meets the warm air from the attic.

Can you replace a roof with shingles?

Most property owners assume that a roof replacement means completely tearing down the old existing roof. That’s never the case in most instances, especially when your roof sheathing and shingles structure are both largely intact. Some roofers will install a new layer of roof shingles over the first layer because it is often quick, cost-effective, and reduces waste.

Do shingles show up on inspection?

Whenever you plan to sell your home and have a second layer of shingles on the roof, it will always show on the inspection report done by a potential buyer. The report will be used as a bargaining chip on the selling price of the home.

Can a roofer remove shingles?

The roofer can complete the work faster when he doesn’t have to tear off the existing shingles. Removing the roof is often tricky and time-consuming and may slow down the project and interfere with the timelines. It may require roofers to work for long hours to remove the shingles leading to higher labor costs. As long as the roof is not leaking and no repairs are needed, the task can be completed faster by adding shingles to the existing rooftop.

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Step-By-Step Guide

• The following steps describe very briefly how to install a metal roof over shingles without incurring too many costs. The basic idea with a metal shingle system is that you are screwing shingles to an existing frame of felt or wood that covers the asphalt shingles. This is what enables you to avoid tearing off your old roof.

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