Attic Projects provides professional insulation installation with attic and crawl space cleaning services. Most homeowners have basic cold roofs, but a system known as hot roofs has become increasingly popular. In this article, the experts at Attic Projects discuss the benefits and drawbacks of hot and cold roofs.
What Is a Hot Roof?
Hot roofs date back to the earliest days of attic insulation. In a hot roof, the insulation sits on top of the structural roof framing and directly below the roof decking. As a result, the living areas under the insulation can stay just as warm.
Most homes with flat or pitched roofs use hot roofs. Insulating a sloped roof with this method is difficult and costly. Hot roofs also lack ventilation.
A lack of ventilation increases the possibility of moisture accumulating, which can result in mold growth. However, an air-tight seal can provide more consistent temperatures and a cleaner indoor environment. Hot roofs have the following advantages:
- Easy Install. Contractors can convert an existing flat roof into a hot roof. Retrofitting will result in a much faster installation of the new roofing system.
- No Heat Loss. Thermal bridging is minimal or nonexistent on hot roofs. A hot roof is also energy efficient and lowers energy bills.
- High R-Value. Spray foam with closed cells has the highest insulation value. Compared to fiberglass insulation, which has an R-Value of 4.3, spray foam insulation has an R-Value of 6.8 per inch.
What Is a Cold Roof?
Cold roofing is more popular than hot roofing and is commonly found in homes. The insulation in a cold roof system sits below the structural roof frame and roofing deck. A cold roof can prevent ice dams from forming on a roof deck in colder climates.
Ice dams can cause structural damage to a roof. During the winter, the snow on the roof can melt and refreeze without proper ventilation. Cold roofs use ventilation to help control the roof’s temperature, so the snow doesn’t melt immediately as on a hot roof.
Since ice melts more slowly, fewer ice dams will likely form along the roof’s edge. A cold roof can also reduce the likelihood of moisture issues, such as mold, as it reduces indoor humidity. Cold roofs have the following advantages:
- No Ice Dams: Cold roof systems prevent snow on the roof from melting by creating a constant flow of cold air above the insulation and below the roof decking.
- No Leaks: A leak or damage caused by ice dams can result in expensive roof repairs. If water enters your home, it can destroy personal property and belongings.
- Stay Cool: Cold roofs reduce a home’s cooling costs by keeping it cooler in the summer. The ventilation systems can also help regulate temperature differences. For example, heat cannot easily transfer from the roof to the living room during hot days.
What’s More Cost-effective: Cold Roof vs. Warm Roof?
A hot roof design will enable you to use or live in the attic space. Attics fall under the thermal envelope of a hot roof system. The attic space will stay warm and comfortable like the rest of your home.
However, a hot roof requires spray foam insulation, which is more expensive than fiberglass. The cost per square foot for spray foam ranges from $3.15 to $7.50. Other costs include adding an air barrier and a vapor retarder to prevent moisture leaks and damage.
Cold roofs cost less than hot roof systems. A cold roof will use ventilation such as soffit vents, baffles, or ridge vents. The fiberglass insulation costs $0.65 and $2.00 per square foot, while blown-in costs $1.65 and $3.80 per square foot.
When deciding which type of roof to select, consider the energy efficiency. Cold roofs function better in colder climates by preventing winter ice dam damage and keeping the home cool in the summer. In contrast, hot roofs cost more but provide better insulation and can prevent outside air from entering your home.
What’s the More Energy-Efficient Option – Hot Roof vs. Cold Roof?
The energy efficiency of a hot roof is greater than that of a cold roof. Homeowners can opt for a hot roof if the outside temperature does not reach 20 degrees Fahrenheit or below. Ice dams form at those temperatures in cold weather.
Many homes waste energy by allowing warm air inside during summer and leaking hot air outside during winter. Insulation can prevent drafts, resulting in energy savings ranging from 5% to 30% per year. The energy efficiency of a hot roof is greater than that of a cold roof.
A hot roof design ensures that the entire roof structure is well insulated. Spray foam insulation covers all nooks and crannies to prevent air conditioning from leaving your home. The spray foam acts as an air barrier that saves energy and lowers electricity bills.
Spray foam insulation has a higher R-value and is significantly more efficient than fiberglass insulation. If the climate in your area does not reach extreme temperatures, you can enjoy energy savings by choosing a hot roof.
Frequently Asked Questions (FAQS) – Warm Roof vs. Cold Roof?
Is a Hot Roof a Good Idea?
Yes. Consider a hot roof if you want to prevent air leaks and stay insulated. A hot roof has many advantages, such as better insulation, a usable attic, and energy savings.
How Long Does a Hot Roof Last?
The average lifespan for a hot roof is 15 to 20 years. All roofs and attic spaces can benefit from annual maintenance.
Does the Cold Roof Need Ventilation?
Yes. A cold roof deck with ventilation is the most effective method of preventing melting snow from turning into ice dams.
A hot roof is a great choice for people that live in warmer climates and want energy efficiency. Homes in colder climates can take advantage of cold roofs with built-in ventilation. If you have questions about insulation, roofing materials, and roof installation, give us a call.
Call Attic Projects for a free quote and more information on hot and cold roofs. Contact us today.