Metal roofing provides exceptional durability and endurance that asphalt shingles just cannot match, yet roofing a home with old asphalt shingles can be intimidating. While installing a metal roof is a project that many people can do, removing the old asphalt shingles is a big endeavor that many people avoid.
One option is to leave the asphalt shingles alone. Laying metal roofing over existing shingles may save you money on roof replacement, and save you the effort of dismantling the roof, and cut the time it takes to build a new roof in half. In this post, we’ll look at the ins and outs of putting metal roofing over shingles, as well as the advantages of this form of roof installation and the dangers to avoid.
Why Install Metal Roofing Over Existing Shingles?
While metal roofing is not suited for many homes since it is renowned for being loud during rainy seasons, it does have various advantages over ordinary asphalt shingles. First and foremost, it lasts far longer. Whereas an asphalt roof has a maximum lifespan of 20 years, a metal roof can last 40 to 70 years, depending on the material.
This is mostly due to the fact that metal roofs are more robust and can resist harsh weather. Some metal roofs can withstand prolonged gusts of up to 140 miles per hour. They can also be extremely durable and will not break like asphalt shingles, depending on the type.
Because of their smooth vs rough surface, metal roofs are less likely to catch debris such as leaves and branches. Furthermore, whereas asphalt tends to reflect the sun’s rays and heat up, metal roofs will deflect the sun’s UV rays, which can result in up to a 25% decrease in cooling expenses.
Metal roofs are also a green alternative, with most metal roofs containing between 25 and 95 percent recycled content. And, because they are all made of metal, they are completely recyclable at the end of their lifespan. Asphalt shingles, on the other hand, are usually disposed of in a dump.
There are several benefits to installing a metal roof over shingles. First and foremost, it removes the need to pull off the old roof, which is more difficult than just installing the new roof.
Removing an old roof is also quite expensive, since it necessitates the rental of a substantial landfill container, not to mention the per-pound expense of discarding the debris at a landfill. The metal roof adds another layer of insulation to a new roof by keeping the asphalt shingles.
Installing Metal Roof Over Shingles Pros and Cons
Before starting with a metal roof installation over existing asphalt shingles, it is essential to evaluate the upsides and downsides of this job.
Pros
- It saves money on the expense of removing an existing roof. Asphalt shingle disposal necessitates the pricey expenditures of a dumpster rental and disposal costs.
- It eliminates the need for ripping off existing shingles. Removing old shingles necessitates the removal of hundreds, if not thousands, of pounds of old material. That’s a lot of effort.
- Maintaining the asphalt shingle layer makes the roof more insulated, lowering energy expenses.
Cons
- Inconsistencies in old asphalt shingles might cause the roof to be uneven. This can make correctly installing a metal roof on top of it problematic.
- Removing old asphalt shingles allows you to inspect the roof’s condition. Without removing the asphalt shingles, you won’t be able to notice any rotting or damaged areas.
- Putting a metal roof on top of shingles adds weight, lowering the live load a roof can withstand. While the weight may not be enough to create difficulties, it is something to think about, especially for roofs that receive a lot of snowfall.
Can You Put Metal Roofing Over Asphalt Shingles?
Most of the time, you can; but, there are certain exceptions. First, check your local building rules to see if putting a metal roof over shingles is legal.
Keep in mind that most municipalities will not permit a property to have more than two layers of shingles. As a result, if your home already has a double coating of asphalt shingles, you will be unable to add another layer on top of it. This regulation exists for a purpose. Three layers of roofing are just too heavy for the roof to support.
Metal roofing can be installed over asphalt shingles if the local building code allows it and there is just a single layer of asphalt shingles on the roof.