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Can You Put 2 Layers Of Shingles On A Roof

When Can You Install A Layover

How to Repair Shingle Damage (2:36 Version) | Flex Seal®

Layovers as a repair technique are the equivalent of putting a bandaid on a bandaid. It doesnt look right and it just makes things worse. Even the ideal conditions for a layover arent ideal. Your roof would have to be lacking any of the signifies that repair is necessary, which would mean that youd basically have to have a new roof. But a layover is bad for your new roof!

A second layer of shingles will decrease the integrity of your new roof and lower its lifespan. Thats because shingles arent designed to have a second layer of shingles on top of them! Plus, all that extra moisture and heat being applied to the first layer of shingles will make that first layer age faster.

The Importance Of A Good Foundation

The wood between your attic and your shingles is called decking or sheathing. When your old roofing materials are bad enough to be replaced, theres a chance that this wood layer has been damaged, too. Depending on your climate this means the sheathing could be some combination of saggy, brittle, spongy, rotten, et cetera.

When you dont remove the existing roofing materials then you dont get to see the condition of the decking. As you can imagine, new shingles over bad wood is less than ideal. Here are just a few reasons:

  • When we apply your new shingles, the nails need good wood to grab on to.
  • Inspectors, contractors, residents, and others on the roof could fall through a rotten spot injuring themselves and the objects below.
  • If damaged wood is adjacent to pipes, vents, satellite dishes, or skylights then those systems can be weakened or stressed.
  • In a storm rotten wood is less strong.

Less critical, but also a factor: you cant see what kind of system components you have. You may or may not have the right system materials in the right places. Between the decking and your shingles you should have some combination of flashing, ice and water shield, and a felt or synthetic underlayment.

Common Roof Problems To Watch Out For Before Going Solar

1. Roof Age

Modern PV solar panels are designed to generate power from solar energy for 25 to 30 years, with only minimal loss in annual energy-generating capacity. So, the real question is whether your roof will match the longevity and durability of solar panels it will house?

Did you know? SunPower offers solar panels with degradation rates as low as 0.3% per year. High efficiency solar panels from LG and Panasonic also offer very low annual degradation rates.

If you are like most homeowners considering going the solar route, then you probably have an architectural style asphalt roof that has recently been installed, meaning that 20 years would seem like a reasonable lifespan to expect from your roof.

However, if instead of architectural shingles, you happen to have 3-tab shingles and the roof is already five years old or even older, then installing solar panels may not be such a smart move for you, because chances are your solar panels will last longer than the roof itself!

While solar panels can be removed to allow for re-roofing a home, thats often too expensive to be reasonable. Its more cost-effective to install PV panels on a roof at the time of replacement.

Pro Tip: Make sure that your roof will last the lifetime of a solar power system to avoid costly solar panel removals and re-installations to accommodate for the installation of a new in-between roof.

2. Excessive Roof Weight

New Shingle Roof Average price

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Leak Investigation And Repair Become Complex

Leaks in a single-layer roof are relatively straightforward to diagnose and repair for an experienced roofer. Many repairs are done in an hour or two with standard supplies that are probably already on the truck.

Not so with double-layer roofs. Water travels differently so subtle damage is harder to find.

Even with obvious damage like a branch through the roof there is so much more to deal with. Think about re-layering lasagna after its already been cooked. If you just fix the visible top layer, it will sag if theres a void below it. If you fix the bottom layer, the top layers will be disturbed. Things get complicated, slow, and expensive, pretty quickly.

Negative Marks On Inspection Reports


Many homeowners planning to sell their homes soon might be tempted to add new roof shingles over old ones for a quick roofing fix while saving a buck. Why pay for a tear-off if you can get away without it?

Besides, it will be a problem for the next owners. They will be the ones who will get stuck with the additional expense of a two-layer tear down along with any issues that may arise from an improper re-roof job.

As home inspectors are aware of this mentality, they will often spot the layered shingles and mark it as a negative on an inspection report to warn the buyers of the potential problems associated with double-layer roofs.

It will be a better idea to discuss your options with the local real estate pros and home inspectors if your home needs to be roofed before putting it up for sale to be entirely sure of the effects it will have on the sale of your home.

Fahey Roofing Contractors is the trusty roofing contractor that will help with necessary roof repairs and replacement. Check out our residential and commercial roof repair services on our website or contact us at 826-1333 to learn more.

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The Importance Of Quality Roof Shingles

The biggest mistake people make when layering roofing is to purchase cheap shingles for the new roof. They seldom consider that in 15 years, when their roofing once again fails, they will have to pay significantly more to have someone remove both layers of shingles and apply new ones.

Savvy homeowners are aware of this fact and may balk at buying a layered roof. Home inspectors are also aware that the thicker the roof, the less hold the roofing nails have in the sheathing. In a high wind situation, this can mean the difference between the shingles staying on, or being pulled off the roof.

The Importance Of Roof Pitch

Q: Everything being equal , which roof will last longer: one with a steep pitch or one with a shallow pitch? Seems to me a steep hillside erodes more quickly than a low slope, so I’d think that roof shingles would wear out more quickly on a steeply sloped roof.

George, Oglesby, Ill.

A:Tom Silva replies: It’s difficult to say. On one hand, a steep roof is less likely to collect leaves and other debris that hold moisture against the shingles and invite the growth of moss and algae. On the other hand, that same roof in an unshaded area facing due south will take the full brunt of the sun, which is hard on any roof.

Actually, factors other than pitch have a greater effect on shingle durability. The side facing your worst weather typically fares worse than the leeward side. Likewise, a roof system that isn’t vented properly and allows heat to build up beneath the roofing has a shorter life than one that is vented.

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It Hides Roofing Issues That Make Repairs Difficult

Any minor issues of your roof can be fixed by a roofer as they are identified early on. However, these problems will remain hidden if another layer of shingles is added on top of the existing roof. This can result to minor and repairable issues to become worse as time passes.

The structural and aesthetic damage caused by an unaddressed roof issue can still be seen on layered asphalt shingles as the first layer will tend to break down more quickly and retain moisture. This will rot your decking while increasing the likelihood of growing mold and mildew in the home.

However, its still unlikely that your roofer would find the root source of the leak. They would need to remove the existing shingles to see the roof decking, thoroughly inspect it, and identify any current issues.

The simple roof repair job can become much more challenging and expensive once the newly installed and the old shingle roof layer has been removed. All because you decided to save money when replacing your roof.

Builder Suggests Overlaying A Roof: Here’s What You Should Know

How to Install Roof Shingles | Ask This Old House

Q: We need a new roof. A builder suggested overlaying over the existing layer of shingles. Is it wise to do this? My concern is how would we know about any underlying damage? I would appreciate any input about the pros and cons of this method.

A: In general, it is not good practice to overlay a traditional asphalt shingle roof versus a complete tear off and replacement for the very reason you stated: you can’t examine the decking to determine if there is any damage that needs repaired. If you don’t take your roof down to the sheathing, you will never know if you have proper underlayment, or are experiencing sheathing rot, or ice or water damage.

The best-case scenario for an overlay is sound decking no previous or existing leaks and a roof with no sidewalls where flashing is needed to tie in the roofing material to the exterior walls of the home. But if you overlay, you cannot install an ice and water-leak barrier, as it has to adhere directly to the wood decking. So, if you have an ice dam in the wintertime, it could easily travel under the overlay and leak under the old roof.

The second layer is also more difficult to install properly compared to new shingles. Flashing around roof penetrations and sidewalls can be compromised. Plus, depending upon the size of your roof, you’ve added multiple tons of weight, which could pose a big problem if there is significant snow accumulation.

Angie Hicks /MCT

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Can I Put A Second Layer Of Shingles On My Roof

Can I put a second layer of shingles on my roof? You can, but you probably shouldnt! Known as a layover, putting a second layer of shingles on your roof is in most cases inadvisable and a job that Proven Roofing is likely to even turn down. There are many reasons why you shouldnt do spot repairs and should instead replace your roof entirely, but a layover has its own unique set of cons that merit investigation.

Valley Details For Re

Any type of valley flashing will work and simply lays over the existing flashing .

Unless a metal valley flashing is used, the first step is to line the existing valley with a new underlayment consisting of either 90-pound roll roofing or a more durable modified bitumen membrane. Then install either a closed or woven valley as described above.

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How To Lay Shingles

This article was co-authored by David Bitan. David Bitan is a roofing professional, licensed contractor, and the owner and founder of Bumble Roofing based in Southern California. With over 12 years of construction industry experience, David specializes in restoring, repairing, and maintaining residential, commercial, and industrial roofs. With over 60 years of combined experience, Bumble Roofing provides easy, friendly services to structures including residential, commercial, industrial, multi-family, and government buildings along with hospitals, hotels, and churches.wikiHow marks an article as reader-approved once it receives enough positive feedback. In this case, 90% of readers who voted found the article helpful, earning it our reader-approved status. This article has been viewed 645,424 times.

Shingles protect sloping rooftops from the effects of rain, snow and hail while providing an attractive crown for the house. Keeping a solid roofing layer of shingles is an important way to avoid water damage and leaks. Doing it properly will keep you without problems for 20 or 40 years. Laying shingles can be hard and hot work, but the reward of an attractive, watertight roof can be worth it.

Roofing Nails That Missed Their Target

Roofer used two different batches of shingles ...

Q: In replacing my wood-shingle roof with cement-tile roof, I noticed that the nailer sometimes missed the trusses when attaching the sheathing. I’ve heard that if I leave them they may work their way through the underlayment and cause leaks. Should I worry about these nails?

Susan, Weston, Fla.

A:Tom Silva replies: By all means yes! Whenever a nail misses its target, it should be removed.

The installer of the roof shouldn’t have left them there. So if possible you may want to contact the contractor who installed your old roof. If that’s not an option you’re going to have to have your new contractor get those nails out.

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Pros To Overlaying A Shingle Roof

Its cheaper. The most common pro for overlaying a roof is saving money. The average re-roofing job will cost about $600 less than a tear-off job, and youll save a little on cleanup, disposal costs and dumpster rentals, too.

Its not as messy. Because youre not ripping off an entire shingle roof, obviously the job wont be as messy.

Its faster. Again, when youre eliminating the entire stage of tearing off a roof, it will save time.

What Are The Disadvantages Of More Than One Layer Of Shingles

When a second layer of shingles is laid over the first, roofers do not usually apply a water and ice shield before laying the second layer of shingles. This means that if there is damage to the layer underneath, the roof is vulnerable to water and ice getting in under both layers. The second layer of shingles would also need to be heavyweight shingles to hide hollows and higher spots on the roof.

These are more expensive than the single weight shingles. The second layer of shingles will add stress to the structure due to the extra weight. This can result in settling and movement of the house which can cause some foundation and wall cracks to develop. Even if the house has a concrete foundation, premature settling can cause damage.

There is added time and labor costs involved in a prolonged roof inspection if there is damage to the roof in the future. Storm repairs will cost more due to 2 layers of shingles needing to be removed for the repair work. Roofing over asphalt shingles can diminish and even invalidate the manufacturers warranty.

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Can You Lay New Roof Shingles Over Old

The answer is yes, you can lay new roof shingles over old ones. Now that we’ve taken care of the primary question at hand, we’ll consider a couple of reasons why you might want to do this. Then we’ll look a lot more reasons why you might not want to do this. But before we get started, one thing must be clear: adding new roofing over old is possible only with asphalt shingles . You can’t do it with wood or slate, for example, and you should never mix materials, such as laying asphalt shingles over cedar shakes. Also, the old roofing has to be in pretty good condition. Otherwise you’re just putting lipstick on a pig.

Roofing Over Your Existing Roof Is Not Worth It

How to Install Flashing on a Roof | Mastering the Roof by GAF

If you havent noticed yet, we are not fans of shingle overs not at all. We dont recommend them nor do we do them. Over the years, weve seen problems caused by shingle overs. Does it cost more to tear off? Yes. However, by spending a little more now, you can save yourself thousands in the long run.

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Question : Why Leave Shingles When Installing A Metal Roof

Find a better roofing contractor. The old roofing should be removed, underlayment installed and furring strips screwed down for the metal to be fastened to. Dont let the installer screw the metal to plywood sheathing. It wont hold over time. If the old roof needs to be replaced why leave it there and not make sure there are no underlying problems before covering it over again? Also, the extra weight could be too much for your framing and cause cracking or other structural problems.

· Todd Shell, Angies List

1. Some metal roofing contractors are trying to convince people that you do not need roof wrap under metal roofing presumably so they can get their initial installed cost more competitive with other roofing materials. Dont fall for that metal roofs do leak at times, and without the roof wrap you have nothing to keep the water from saturating and rotting the sheathing and rafters, destroying your entire roof.

2. Also, if your roofing is flat sheet raised seam rather than corrugated, the batts or nailing strips should be discontinuous small gaps are needed every few feet to allow hot air to flow up to the ridge vent , otherwise it just becomes an oven between the roofing and the sheathing, plus the sheathing gets much hotter and makes your entire attic hotter in the summer.

3. It saves having to fill up landfills with old shingles.

· Unknown, Angies List

Subtle Issues To Complicate Things

When you need shingles for your roof, its best to get several quotes from different roofers. Theyre going to give you the best idea about what is possible with the budget that you have. Because you can often lay other roof types over an intact asphalt shingle layer without issue, it could be cheaper to go that route and avoid a tear-off entirely. But, this is only something your expert can tell you for sure.

Other things to consider when pondering the re-roofing issue include:

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