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Can I Go Over My Old Roof Instead of Doing A Roof Replacement?

September 13th, 2021 | 5 min. read

Can I Go Over My Old Roof Instead of Doing A Roof Replacement?

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If you’re on your way to having your roof replaced, and don’t know if you can go over your old roof, then rest assured we will do our best to answer your questions.


While many say it’s better to have your entire roof torn off and replaced from scratch, there is a possibility of having your roof replaced on top of your old roof. A lot of homeowners do it, especially if the foundation of their previous roof is sturdy and supports the structural integrity of the property below. But, there are a few key aspects that you should consider before making this decision and getting a roof replacement done on your old roof.


Roof Replacement Vs. Reroofing – The Basics


When it comes to roof replacement, it requires a lot of time and hard work. It includes the complete reinstallation of the roof, the process of which starts with tearing your existing roof completely off. Everything, down to the deck of the roof is taken off and the process of installing a roof is done from scratch. No matter what layers of shingle your roof may have, it is all torn away to start the new roof installation. This process requires more labor and crew members to get it done in a timely manner.


On the other hand reroofing or having a roof installed over your old roof, entails the addition of a new roof over the old. This is usually the case when the old roof has no underlying problems such as a leakage problem after a rain spell. It may just be reaching its end life and losing its functionality. This is also known as an overlay where no tearing-off takes place. But, it is important to note that this process is typically done only once. This is because it is impractical to have more than two layers of shingles on your roof at a time.


When Is It Possible To Go Over Your Old Roof i.e. Reroof?


Let’s break down some of the aspects which can make reroofing possible. Here are some of them:


  • If you live above the “Mason-Dixon line” which is the Northern regions of the United States, most shingle manufacturers will NOT warranty their shingles if they have been installed over old shingles in the Southern regions of the United States as it is too hot and humid and so the new shingles will blister and fail prematurely.
  • When your old roof has reached its end life, for the Northern States.
  • The granules on your shingles may be wearing off due to the harsh weather but have not resulted in curling yet.
  • When there are no roof leaks or underlying problems.
  • When you wish to change the exterior of your home at an affordable cost. You may want a new color, depth, and dimension to your roof during a home renovation project.
  • When you wish to achieve a new look to your home without having to spend too much time and money on it. Reroofing is quick, effective, and costs way less than a roof replacement.


When Is It Not Feasible To Go Over Your Old Roof?


For reroofing, there are a few factors that you can look out for that may make the process unfeasible. Here are some of them.

  • If you live below the “Mason-Dixon line” or the Southern States.
  • If your contractor advises on a roof replacement over reroofing, it’s best to go with their opinion. The roofing inspection conducted by them is sure to be accurate even if you are not experiencing any visible roof damage.
  • If you don’t have asphalt shingles, reroofing may not be possible. This is because only shingles can be placed over old shingles. If you wish to have a wooden roof over shingles, it may not be possible as overlaying different materials may shorten the durability going forward.
  • If you have already gotten a roof replacement done over your old roof, then doing it the third time may not be possible. This can make your roof too heavy and become unsafe to live under.
  • If there is extensive damage to your roof, then going over the old roof is often not recommended. It is better to go for a full roof replacement instead.
  • Curling shingles due to improper attic ventilation, trapped moisture, or inept installation. Here going over your roof is only possible if your shingles are flat and at a level. Otherwise, roof replacement and having the shingles installed from scratch is the way to go.


Pros And Cons Of Going Over Your Roof


To wrap it up, the following list of pros and cons of going over your old roof during a roof replacement can helps narrow things down, helping you make an informed decision of which option to go for based on the condition of your existing roof.


The Pros


two story home with complex roof
  • It’s cheaper than a roof replacement.
  • Requires less labor and is less time-consuming compared to a roof replacement.
  • A quick fix to your home renovation project, making your home look brand new in no time.
  • Prolongs the longevity of your roof by 15-20 years.


The Cons


  • Underlying roof issues may be overlooked.
  • Makes the roof heavier.
  • Two layers trap and retain more heat, making your home hotter and causing premature deterioration of the shingles.
  • Possibility of bacterial and fungal growth under the top layer if not installed properly.
  • The long-term cost of removing both layers and having a new roof replacement procedure done from scratch.


The Key Takeaway


If you seek to get a roof replacement done over an old roof, a lot of planning and calculation can go into making sure it happens the right way. And for this, a professional roofing contractor is where you want to start. They have all the tools needed to ensure a sturdy and leak free roof replacement is done for your home or business. So, before getting on board, consider all the tips and key elements, they’re sure to come in handy and save you both time and money going forward.  If you are still considering the benefits of a roof replacement compared to a repair, check out our next article:

What Are the Pros and Cons of Doing a Full Roof Replacement Vs Roof Repair