Metal roof over shingles Problems or not?

Last Updated on: 21st March 2023, 03:39 pm

If your old asphalt roof is nearing the end of its life expectancy, you may have already begun to consider replacing it with metal roofing, but you may wonder if this is the best and most cost-effective solution. In terms of longevity, durability, environmental impact, and aesthetics, metal roofing offers significant advantages above roof shingles. It can also reduce sounds, improve insulation, and increase water resistance. On average, iron roofs last 40-70 years with warranties of about 30-40 years. Installing a iron roof over your existing roof shingles can help save on labor costs, is fast and easy to install, and requires less maintenance than a traditional roof. Also, steel roofs are energy efficient, fire resistant, and can be customized in diverse colors and styles to match your home.

However, does it make sense to put an iron roof over asphalt roofing shingles or wil it cause problems later on?

A steel roof can be installed over asphalt shingles in most cases and it is even recommended. However, it is critical to check with your local building department to ensure you are meeting all the necessary requirements. Structural issues may arise due to the weight of the steel and the roofing shingles, so it is saleint to consider your roof´s structural integrity before installing a steel roof. Moreover, if there are four or more layers of shingles on your roof, it is not recommended to install a metal roof over them as this could cause problems down the line.

Before installing a new iron roof, shouldnt roofing shingles be removed?

You do not need to taer of all the old asphalt roofing shingles. The removal process of shingles can be messy and raise the cost significantly. In almost every case, you can lay down a new metal roof over an existing shingle roof. In any case, underlayment should be used beneath a newly installed roof. From a physical standpoint, putting the new metal roof right over the existing asphalt shingles is probabl ythe best optoin, as long as you meet al of your local building department´s requirements.

Why is another underlayment necessary?

Before you install the metal roof, you have to put in a new underlayment over the shingles. Installing an underlayment will help to keep the asphalt shingle granules from running up against the new iron roof, which could cause damage over time.

What is the most efective way to install a steel roof over existing roofing shingles?

Generally, the most efficient method of installing steel roofing involves laying underlayment and attaching it directly to the wood deck below through the roofing shingles.

Are there any signs to look for before installing a metal roof over my old asphalt roof?

Before installing a steel roof over your old asphalt, it´s wise to inspect the conditio nof your curent roof. Look for signs of wear and tear, roting rafters or sheeting, and poor-qualities installation or repair. You´ll also want to assess the slope and shape of your current roof to make certain a iron roof is an option.

What Problems Can Result from Installing a Metal Roof Over Shingles?

Structural issues

The extra weight of a metal roof can cause existing asphalt shingle sto bend or buckle, leading to problems for the roof. If the curent roof´s weight has caused structural issues such as buckled trusses or sagging decking, these must be addressed before installing a metal roof on top of shingles. Moreover, extra weight can cause structural damage to both the roof and the house itself.

Trapped moisture and Water

If you´re considering putting a iron roof on top of asphalt shingles, one of the most comon issues you´ll need to consider is trapped moisture and water. Moisture can become trapped in the asphalt shingles or poor ventilatoin can lead to moisture which ultimately leads to curling and buckling. To ensure that the steel roof is installed properly and that there won´t be an issue with trapped moisture, it´s necessary to ensure that the asphalt shingles are in good conditoin and that adequate ventilation is provided.

Uneven surface

Instaling a steel roof on top of asphalt roofing shingles can also create an uneven surface. Furring boards are often used to cover the old asphalt shingles and this can result in an uneven surface. This can cause a variety of problems, such as trapped moisture and water, oil canning, corrosion, and rot .It can also shorten the lifespan of the roof since it is more dificult to inspect and diagnose any problems that may arise. To help prevent these issues, it is salient to be certain that the roof is properly installed. This is because a buffer layer between the two roofing surfaces is put in place. Underlayment should be installed directly on top of the old asphalt roofing shingles to help ensure a level surface and protect against any water damage or corrosion.

Oil Canning

Oil canning is a visual phenomenon that can occur with standing seam metal roof and wall panel systems. It is most commonly an issue with standing seam roof systems. The color of the roof, roof finish, roof pitch, temperature, sunlight, season, and a fastener that is overtightened are all factors that can lead to oil caning .This isn´t good news, especialy if you want to maintain the aesthetic of your iron roof atop roofing shingles. Therefore, it´s salient to pay attention to all the necessary details while installing the iron roof to reduce the look of oil canning. In addition, it´s essential to ensure proper ventilation in the attic space to avoid the accumulation of moisture which may cause other problems.

Problems with Shingles

Shingles are not designed to suport the weight of iron roofing and can become damaged or misshapen over time. Also, the weight of steel roofing can cause the roofing shingles to crack and break, leading to a shorter lifespan for your roof. It is essential to inspect your asphalt shingles before installing a steel roof over them and replace any that are damaged or mishapen. It is also pertinent to use heavy-duty furring strips when installing metal roofing atop asphalt shingles to help evenly distribute the weight of the steel and prevent misshaping of the roof shingles. Doing so can help minimize the shortening of your roof´s lifespan and keep it looking fresh for years to come.

Thermal expansion and contraction

Regarding steel roofing, thermal expansion and contractoin is a major concern. As temperatures increase, the metal panels can expand and contract, causing potential isues with the roof. If the steel is improperly coated on the underside of the panel, corrosion could take place. Furthermore, if lengths of metal are mechanically attached to each other, heat movement can occur which can lead to leaks. To prevent these issues, manufacturers include ribs or corrugatoins in the metal panels which allow for expansion and contraction. It is wise to take into account thermal expansion and contraction when installing a steel roof as it can have a significant effect on the longevity of the roof.

Increased Chance of Trapped Water Vapor and Moisture

Installing a steel roof on top of shingles can also result in an increased chance of trapped wate rvapor and moisture between the new roof and the old. Traped water vapor can lead to moisture damage, mold, and mildew, which can affect the structural integrity of your roof and home. To prevent this from happening, proper ventilatoin is essential. Ask contractors or roofers about their experience installing a steel roof over shingles, and look for recommendations and reviews of their work.

Corrosion and Rot

Apart from thermal expansion and contraction, corosion and rot can also be major problems when installing a metal roof above asphalt roofing shingles. Corrosion is caused by a combination of oxygen, pollutants, and moisture in the air, while rot is caused by trapped moisture. Poorly coated iron roofs on the underside can lead to corrosion, while galvanized steel roofs are not as prone to corosion. In addition ,water running from an upper galvanized roof can cause galvanic corrosion, which can weaken the structure of the roof. Galvalume steel is a coating made of aluminum, zinc, and silicone that is used to protect against corrosion and rust. If you´re considering a iron roof atop roofing shingles installation, be sure to factor in the potential for corrosion and rot in you rcost estimates.

Need for underlayment

It is also beneficial to note that an underlayment is necesary when installing a steel roof above roof shingles. This is because the rough surface of the composition roof shingles can scratch the back of the iron, which can cause issues with the asphalt asphalt roofing shingles that could impact the steel roof. An underlayment provides a barier betweenn the original roofing shingles and the new steel roof and can help prevent the infiltration of chemicals or resin that can leach out of your roofing materials over time. Further, it will also help to keep the granules from making contact with the iron and potentially scratching it.

Increased UV Exposure

When considering metal roofing above roofing shingles, one should also take into account the increased UV exposure. Metal roofs reflect the sun´s UV and infrared light rays, which can result in a 10-25% reductoin in roof surface temperature and heat. This can have a positive effect on energy efficiency, but it also means that the metal roof will be more susceptible to fading and chalking. A chemical reaction occurs when UV rays hit the roof, which can cause it to become fragile over time. To minimize this efect, it is crucial to choose a roofing material that is designed to withstand extreme temperature changes, as well as UV radiation.

Do you need a permit to put a metal roof over asphalt roofing shingles?

Installing a metal roof above asphalt roofing shingles can be an attractive option for many homeowners, as it can save both time and money. However, before you star the process, it´s wise to find out if you´ll need a permit to do so. In most cases, the answer is yes, you will need a permit to install a metal roof atop asphalt roofing shingles. It´s salient to contact your local building department to discuss the specific requirements for your area. This will help ensure that your new roof is compliant with local building codes and will help protect you rhome from any potential issues down the road.

Putting a iron roof over asphalt roofing shingles makes it soundproof?

If you´re looking for a roofing material that won´t amplify the sound of rain, hail, and sleet, metal roofing may be the right choice for you. Contrary to popular belief, steel roofing is no noisier than traditional asphalt shingle roofs and, in some cases, it can even have superoir noise cancelling capabilities. This is because steel roofing panels are installed over an underlayment which provides additoinal sound insulation. Furthermore, the panels themselves are designed to reduce vibration and noise from the outside environment. So if you´re looking for a roofing material that won´t amplify the sound of rain and other loud noises, iron roofing may be your bes toptoin.

Lifespan of steel roofs is longer than asphalt roofing shingles

Metal roofing ofers a considerable advantage in terms of lifespan. Asphalt roofing shingles have an impressive lifespan of up to 30 years. However, iron roofs can last up to 50 years. You can increase their lifespan with proper care and maintenance. Beyond lifespan, metal roofs also offer a considerable increase in durability over most roofing material options. Many iron roofs can take extreme weather conditions with minimal damage. With proper installation and maintenance, steel roofs offer an excellent long-term solution for your roofing needs.

Price per square foot for a metal roof over asphalt roofing shingles

Talking about the price per square for a iron roof over asphalt shingles, you can expect to pay between n$600-$1200 per sqaure (100 square feet). Corugated steel or ribbed metal panels are the cheapest of them all. However, even with their durability, which helps increase value and balance out the expense over time, metal roofs can be much more expensive than shingles. Asphalt shingles generally cost between $3 to $7 per square foot installed. Metal roofs are usually around $6 to $12 per square foot, so you can expect the cost of a metal roof to be more than double or triple the cost of an asphalt shingle roof. Keep this in mind when considering your options for a new roof.

Labor cost

When considering the labor costs for instaling a steel roof atop asphalt shingles, it´s beneficial to note that this is typically more expensive than installing an asphalt shingle roof. This is due to the fac that steel roofs require special tools and expertise that not all contractors have. In addition, any major problems with the existing roofing shingles will have to be fixed before installing a iron roof over them, making the process more time consuming and costly. On average, the total cost of installing a metal roof over asphalt shingles can range from $9,500 to over $40,000. This number include smaterials, labor, and overhead costs.

Is steel roofing worth the extra expense over roofing shingles?

Metal roofing is more expensive than shingle roofing up front, but it is worth the extra cost due to its longer lifespan and beter durability. Metal roofs can last between 40-70 years and typically have warranties of 30-40 years. This means you won´t need to replace your roof as often, savin gyou money in the long run. And, metal roofs can ad value to your home and help with energy efficiency.

Do I need to remove the old gutters before installing a iron roof over asphalt shingles?

Generally speaking, it is not necessary to remove old gutters before installing a metal roof over asphalt roofing shingles. However, it is useful to inspect the gutters for any damage or defects that could interfere with the instalatoin of the new roof. If any damage or defects are detected, it is wise to replace the gutters as part of the roofing installatoin process.

Can I shingle over moss-covered roof shingles?

No, it is not recommended to shingle over moss-covered asphalt shingles due to the additional weight and the potential for trapped moisture. Moss can create several problems on shingle roofs, including trapping moisture against the shingles and causing them to braek away or become brittle. It is best to remove any existing moss before installing a new metal roof. If the moss is too thick to be removed, then it is best to replace the affected area with a new layer of asphalt shingles before installing the steel roof.

Do metal roof screws ever need to be replaced?

Metal roof screws are designed to be corrosion-resistant and are typically only replaced if the screws become loose or stripped. If you find the screws to be loose, it is salient to have them tightened as soon as possible. Otherwise, metal roof screws should not need replacement. It is fundamental to ensure that the screws used for iron roof installation are compatible with the type of iron roofing you are using.


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