Can You Put New Shingles On Top Of Old Ones

by | Nov 19, 2020 | Blog | 0 comments

Opting for a roof replacement plan can seem like a tricky option for many homeowners. In almost every situation, roofing contractors that undertake the job will advise you to go for a full roof replacement. However, in certain circumstances, you can get through by simply going for a reroofing job as it seems more appropriate. So what are some of the cases in which going for a layer of new shingles over the old one is applicable?

Putting new shingles over old ones works well if the old ones are in good condition or if there needs to be a change of color or design in the roof. Placing new shingles over the old ones instead of replacing them is a good option with a tight budget since it is undoubtedly a much more affordable option than roof replacement.

Everyone likes to add something new to their house every and now then, and if you feel the same way about the shingles on your roof, then here’s something you can do about it.

Why Should You Add New Roof Shingles Over Your Old One?

It might apparently seem like an obvious benefit to having multiple layers of shingles, but it is important to make it clear that it does not necessarily make your roof more waterproof. You will notice that more than half the time, it ends up creating problems for you than before.

But is there a reason for you to lay new roof shingles over the old ones? We think two things play a significant role in determining this. These two aspects are convenience and cost. If you decide to make the old shingles stick around, you can skip the messy and laborious removal process called the “tear-off.” This will save you money on the roof job.

However, both of these benefits come with certain limitations. It’s relatively easier and cheap to leave behind the old shingles in place, but then you have to get on with some special prep work that goes into reroofing. This will involve removing vents, ridge caps, and misshapen shingles, along with other things.

 

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Sometimes, you still have to switch or add new flashing, which can be tricky sometimes as compared to old roofing. Once you eliminate the tear-off process, you can easily save up repairing costs of up to $1,000 or more that would otherwise be spent for a new roof. More than that, it will also save you time since it definitely involves much less hassle.

Why Should You Not Add New Roof Shingles Over Old?

Now we will explain why the potential cons that come with reroofing tend to offset the potential pros, but it all depends on your situation. As you read ahead, the following list includes some universal reasons not to reroof as well as some considerations or things to check out if you seriously want to add new roof shingles over your old ones.

Whether you want to repair one section of your roof or replace all of it, it’s always a good idea to pull up the old shingles first before you can put down the new ones.

 

Why Should You Not Add New Roof Shingles Over Old
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· Shingles Work Best For Flat Surfaces

They don’t perform a decent job of bridging over gaps, dips, or humps, which may include the stepped texture created by overlapping shingles. Re-roofers have tips that can lay new roof shingles over existing ones so that the same sort of step-ups between each course can be maintained.

In case any old shingles around you are cupped, curled, or otherwise bad in shape, then those defects will reflect onto the new layer as well. For this reason, several roofing experts recommend using laminated or dimensional shingles for reroofing projects because these tend to be thicker than standard shingles. They also have a staggered edge profile, which helps in hiding any dips or high spots in the old roofing.

·  Shingles Add Weight

Good-quality shingles can weigh up to 350 to 450 pounds per square. Chances are, the roof structure of your property was designed to bear a dead load of one layer of shingles along with extra strength to bear snow and a safety margin.

Installing new roof shingles over the old one effectively adds to the weight of the roofing, so you have to ensure your roof’s structure is capable of handling this extra load. For this reason, many building codes commonly put limitations on reroofing practices so that you can’t add more than two layers.

On certain properties, the extra weight of multiple layers causes the roof sheathing to sag in between the rafters or trusses. Small roofs don’t have the capacity to handle immense amounts of weight, which come around by adding a second layer to your roof only because it increases that strain and can result in further roof problems. This is especially prominent if the area you’re living in receives a great amount of snow each year.

Even for medium-sized homes, the addition of another roof’s worth of weight can cause a number of issues once winter comes by.

· No Visual Inspections For Roof Sheathing

Without a tear-off, roofers are unable to see what the decking looks like. A good roofer will make your roof undergo a careful “walking” inspection to search for spongy areas and other issues. They can make localized repairs before the reroofing process, while an average roofer might be less conscientious towards these tasks.

· Can’t Replace Underlayment

The tarpaper that’s laid between the roof sheathing and the shingles placed down is present for a  good reason. It is there because water has a way of getting under your shingles no matter how hard you try with adding as many layers of the roofing as you can have.

If the underlayment of your shingles ends up being old and deteriorated, it won’t have the integrity to protect your roofing deck from water that can get past the shingles.

During snowy climates, most of the new roofs these days end up with an ice-and-water shield, which is a rubbery moisture membrane that is applied to the sheathing along the eaves to serve as a protection against ice dams.

Adding this layer of membrane isn’t an option that is present with a reroof, and the extra layer of shingles offers little protection against ice dams.

· Reroofing Could Affect The Warranty On Your New Shingles

Make it a point to check with the shingle manufacturer about all warranty issues and relevant installation requirements before you start the reroofing procedures.

· Local Codes May Not Allow Two Layers

Two layers are the highest you can go in most areas, but for some buildings, the restriction is one. For instance, towns located in climates that have a heavy hailstorm or significant ice dam issues may not allow for multiple roofing layers.

· High Costs

Eventually, you will figure out that overlaying new shingles can end up being heavier on your pocket than a replacement project. The idea of saving a thousand dollars from a simple reroofing plan may sound appealing as of now, but other costs that work as a later replacement due to the poor base certainly won’t work.

Having old shingles stripped and replaced together with new layers will almost always feel more sustainable in the upcoming years. Every roof that a property has gets replaced eventually due to the reroofing process instead of a full replacement. Therefore, you’ll only be postponing the inevitable reroofing fees for not stopping it in time.

· Lack Of Leak Installation

Overlaying new shingles over the old ones prevents roofers from properly installing water and ice leak barriers. If you are located in an area that has brutal winters or experiences other environmental concerns, water leak barriers are an important topic as they ensure that ice doesn’t leak under the old shingles that have been placed.

A Reroof May Look Bad On Your Inspection Report, And Here’s Why

Adding new roof shingles over the old ones may seem tempting to a lot of people who plan to sell their properties in the near future because why should you pay for a tearoff if you can just get away without it, right?

Due to this reason, the new owners who come in later will be stuck with paying extra for first getting a two-layer tearoff followed by any problems that may arise because of the improper reroof job. Due to this, home inspectors will report double-layer roofs if they find them on your property, which is a way to warn the buyers of potential problems linked with reroofs.

Old shingles restrict contractors from running thorough checks on the condition of the existing roof. Although reroofing remains a possibility for homeowners to look for, the presence of having an “old” roof prevents various roofers from running inspections of the deck to check to make sure if there is any damage to plywood that needs repairs first.

 

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Materials Allowed

It is essential to make it clear at this point that adding new roofing over the old one is only possible with asphalt shingles that are also called “composition shingles.”

You can’t manage such a task with wood or slate. Therefore, you should never mix materials, such as laying down asphalt shingles over shingles made out of cedar shakes. Also, make sure that the old roofing has to be in a pretty neat condition for reroofing. Otherwise, all your money and efforts will go in vain.

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