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Hot Roof vs. A Cold Roof: What’s the Difference?

December 31, 2021 | 4 min. read

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Whether you’re doing a deep dive into the roofing industry or you’re interested in getting a new roof, you may have stumbled across the terms “hot roof” and “cold roof.”


What is a hot or cold roof? Hint: it doesn’t involve your roof’s temperature. 


Terminology or roofing slang like this can cause a roadblock in your roofing research. It can be frustrating to come across commonly used terms but have no idea what they mean.


You don’t have to be a roofing expert to get the best possible education about your roof. That is why Rescue My Roof has spent over a decade in the industry educating our community so they can make the best decisions for their homes. 


In this article, we will be discussing the differences between a hot and cold roof. In the end, you will know the terminology and have a better idea of which one is best for your home. 


What is a Hot Roof?


What is a hot roof graphicA hot roof sounds like an easy concept to grasp. Many would assume it has to do with the temperature of your roof.


In actuality, a hot roof involves roof insulation. A hot roof has insulation attached to the decking and the rafters supporting your roof. 


Hot roofs are unvented, meaning no exhaust vents contribute to the roof ventilation system. 


A Real Hot RoofAdditionally, a hot roof means your entire attic space is included in the building envelope or the interior of your home. This means the air will be conditioned by your home’s heating and cooling systems. 


However, the insulation for a hot roof must be installed and sealed correctly with air foam. Without it, the roof deck will become rotten and will need to be replaced. 

A hot roof can be installed at the same time as your roof. Find a contractor who offers and has references for both services so that you get the quality workmanship you deserve. 


Why is it Called a “Hot Roof?” 


The spray foam insulation is installed directly under the roof deck. As a result, there will be a two to three-degree increase in the temperature of the shingles. 


If a section of your roof is exposed directly to the sun, the increase can even be as high as 15 degrees.


The warmer your roof is, the higher the likelihood of seeing some negative impacts on roof longevity. However, the decrease in lifespan will be slight. 


What is a Cold Roof?


Cold Roof GraphicA cold roof is a vented roof. You will see the traditional ventilation system involving intake and exhaust vents.


Cold roofs have insulation installed underneath the rafters, making them visible. 


This type of roof means your attic is separate from the conditioned space and therefore is not a part of the building envelope. 


Cold roofThe term “cold roof” was not coined by the roof’s temperature. It’s called a cold roof because the rafters of your roof remain uninsulated and visible, making the roof slightly less efficient with heating and cooling. 




The Key Differences Between a Hot Roof and a Cold Roof


Here is the ultimate breakdown you need to determine whether or not a hot roof or a cold roof is for you:


1. Different Efficiencies 


A hot roof is a more efficient option for heating your home.


Because the insulation is installed directly under the roof’s decking, it stops cold air from permeating downwards into your home and lowering your home’s overall temperature.


It will be easier (and less expensive) to heat and cool your home. 


The rafters are exposed with a cold roof, which allows the cold outside temperatures to permit downwards. 


This can make it difficult to heat your home efficiently in the winter. 


If you don’t face severe winters, a cold roof is an option – and one that many people commonly choose. 


2. Repairs


When you have to repair a cold roof, the roof structure must be torn off. 


All shingles and underlayment will be removed to access the necessary areas. This can make the job more costly than warm roof repairs. 


If you want to save money on future repairs, a warm roof may be the best option for you. 


3. Increased Building Height


A warm roof’s insulation is installed above the rafters and below the roof’s decking.


As a result, the thick layer of insulation can add a few inches to the height of your home. 


The home’s profile remains unaffected with a cold roof as all insulation happens underneath the rafters in the attic space. 


4. Ice Dam Prevention


Any insulation will help prevent ice dams, especially when combined with proper ventilation.


However, Hot roofs are more efficient at ice dam prevention because they keep the warm air inside your home and prevent the ice and snow from melting.


If the ice at the peak of your roof cannot melt, then you will likely not experience ice dams. 


Ice dam prevention is still possible whether you decide to go with either a hot roof or a cold roof. As long as your roof’s ventilation system is working adequately, you will have an easier time with ice dams. 


However, if you have experienced severe problems due to ice dams and want a more secure solution, installing a hot roof may be the best option.

How to Decide Between a Hot Roof and a Cold Roof?


Now that you know what a hot and cold roof is and the key differences, the next step is choosing the right insulation method for your home.


If you are worried primarily about budget, a hot roof will be the best option.


Not only are they cheaper to install, but it will be easier to heat and cool your home efficiently. You might see decreased home energy bills as a result. 


If you want a manufacturer’s warranty to make sure your roof quality is ensured over time and do not want to add height to the profile of your home, investing in a cold roof may be the way to go. 


Always consider budget, potential repairs, and warranties when deciding on any roof styles. These three factors will make sure you are prepared in the long run to face any challenges you and your roof may encounter. 


You can learn more about roof maintenance, and energy efficiency with “ What Are Ice Dams? (Causes, Prevention, and Solutions)” and “Active Ventilation vs. Passive Ventilation (How to Choose).”

Are you in the greater Milwaukee area and are ready to talk to a contractor about your roofing options? You can contact Rescue My Roof today to schedule your free roof estimation.