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Hot Roof vs Cold Roof - which is better for EPDM

June 4, 2024 | General
Hot Roof vs Cold Roof - which is better for EPDM

Hot Roof VS. Cold Roof EPDM Installation

When it comes to roofing, there are always aspects which have to be considered when undertaking an expansion or resurfacing project. In this blog post, we focus on one of the most important factors in roof construction: the difference between hot roofs and cold roofs, and the impact this can have on an EPDM roof[ing] installation.

What’s The Difference Between a Hot Roof And Cold Roof

Before we break down how each of these construction techniques impacts your EPDM roof[ing] installation, let’s first break down the difference between these two techniques:

 

What Are Hot Roofs?

In short, a hot roof is designed so that the insulation is attached directly to the roof deck; this eliminates any ventilation gap between the insulation and the roof. By attaching the insulation directly to the roof deck you can ensure that your roof retains more heat and therefore has greater energy efficiency. 

 

There are many additional benefits that hot roofs bring, including:

  • Elimination of condensation, due to the insulation helping the roof retain heat. 

  • Energy efficiency, with less energy needed to maintain the desired internal temperature in colder climates.

  • Greater available space, as the hot roof negates the need for ventilation, leading to more available loft/attic space.

What Are Cold Roofs?

Cold roofs differ from hot roofs in that the insulation is placed between ceiling joists, with a ventilated space above the insulation but below the roof deck. A cold roof construction allows air to circulate above the insulation, helping to keep the roof deck cooler. Much like hot roofs, cold roofs bring a host of benefits, including:

  • Regulation of temperature, ensuring that the roof deck is kept cool due to increased ventilation and reduction of thermal bridging. 

  • Reduced stress to roofing materials, due to the reduction in thermal stress endured by the material.

  • Cost-effectiveness: cold roofs are typically less expensive to install, with less insulation required.

Hot Roof vs. Cold Roof EPDM Installation

As EPDM is a versatile material, it can be installed on both hot and cold roof constructions, however its effectiveness in both scenarios differs greatly and, depending on the climate, may either increase or decrease its efficiency

Advantages of EPDM on cold roof installations:

  • Installation of EPDM on a cold roof can help with temperature regulation, as the cold roof construction reduces the impact of thermal stress on the membrane over time. 

  • A cold roof construction can also complement EPDM’s fantastic reflective properties in warmer climates, helping to keep your home and attic space much cooler.

Advantages of EPDM on hot roof installations:

  • Installing EPDM on a hot roof also brings various benefits, including enhanced energy efficiency in colder climates due to the lack of a need for ventilation space, and EPDM’s fantastic insulative properties.

  • Reduction in condensation, due to the removal of the ventilation layer which may act as a bridge between hot and cold air. Condensation over time may weaken the roof structure or the bond.

Which roof is better for an EPDM roofing installation?

To answer this question, we need to consider several factors, including the climate in which the roof will be installed, the type of roof that the material will be covering, and the projected outcome of the project.

In warmer climates, a cold roof may be more appropriate, as they can regulate temperature and prevent overheating of the roof deck. By complementing EPDM’s reflective properties, a cold deck EPDM installation can help keep both your attic and home cooler. 

However, in cooler climates, a hot roof installation may be more fitting, decreasing energy usage owing to the insulative properties of both the insulation and the hot roof EPDM installation.

Conclusion

In conclusion, the decision should consider the current roof construction, the climatic conditions where the EPDM will be installed, and the type of room/house the installation will cover.

Still Unsure?

If you’re still unsure whether a cold or hot roof installation is best for your project, get in touch with us, or book our one-day training course, where one of our qualified instructors will be more than happy to answer any questions you have. 

If you’re researching for your next project, we supply installation guides, how-to videos, and our handy EPDM roofing calculator, which will generate a quote based on your project requirements. 


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