Membrane roofing systems are just that — systems. The membrane is critically important, but so are other components like fasteners, vapor barriers, and especially the insulation.
Designers and installers should not overlook proper commercial roof insulation because the right choice will save on energy costs and how it’s installed could affect the life of a roof.
What is Commercial Roof Insulation?
Commercial roof insulation is a layer of material installed under the membrane to create a thermal barrier between inside the building and the outside elements. Roof Insulation plays a crucial role in reducing heating and cooling costs for residential and commercial buildings.
The goal is to limit thermal transfer between outdoor and indoor temperatures. Commercial building roof insulation is more of significant concern in any areas that experience extreme climate (either hot or cold) fluctuation. The more you invest in maintaining your building temperature, the more you need to think about installing the right roof insulation and the right R-value the first time. It can provide noticeable energy savings.
Types of Commercial Roof Insulation
There are a wide variety of roof insulation materials, and they range in material type, R-value, installation methods, and manufacturers. A skilled contractor should be able to recommend the best commercial roof insulation for their project.
Here’s a quick look at some of the most widely used commercial roof insulation types:
- Polyisocyanurate (Polyiso)
- Extruded Polystyrene (XPS)
- Expanded Polystyrene (EPS)
- Mineral Wool
- Spray Foam
Commercial Roof Insulation Performance
Commercial roof Insulation materials are installed just below the roof membrane; installation depends on the roof system and manufacturer recommendations. Insulation can be made from a variety of materials and range from rigid boards to liquid applied foam or insulating concrete.
Key considerations when evaluating insulation include:
Insulation R-Value (Thermal Resistance)
R-Value is the measurement of how well a layer of insulation resists the flow of heat. The R-value of a commercial roof takes into account all of the layers in the roof system, but the insulation layer will contribute the most R-value to your building. When comparing R-values, the higher the R-value – the more effective the material. Keep in mind that a material’s R-value will degrade over time as the material ages.
You don’t always want to invest in a high R-value roof system; it’s essential to consider what kind of R-value is appropriate for the environment and building. R-value follows the law of diminishing returns; after a certain thinness, you are no longer getting the same level of benefit from additional layers of insulation. Additionally, too much insulation may increase stress on a roof membrane through the effects of thermal shock.
Insulation Durability and Impact Resistance
Durability is an important part of commercial roofing and outdoor materials as a whole. Mother nature can throw some harsh conditions at us, and you want all of your roof elements to withstand and protect your building. Your roof membrane will serve as the watertight layer and first line of defense in impact resistance when protecting your building - next is the insulation layer. Insulation plays a role in the impact resistance of the roofing system and must be able to withstand the impact conditions of the rooftop environment.
Impact resistance for commercial roof insulation is an ongoing development within the industry as a result of more recent performance standards. Proper insulation selection and system design are critical to a roof systems impact performance to hail, debris, and other objects falling on your roof.
Insulation Fire Resistance
Fire-resistant roofing materials can play a crucial role in preventing fires and limiting their damage. Proper fire testing and certification is critical if you want your roof to be safe, protective, and long-lasting. When selecting a fire-resistant roof system, it’s usually recommended that the system in question has a UL Class A fire-resistance rating or FM Class 1 rating.
Protecting Your Commercial Roof Insulation
No matter how effective the insulating material, it’s crucial to keep it dry. If water makes its way to your roof insulation, this material can become saturated. This saturated material holds in water and is rendered less effective. Wet insulation that is holding water can transfer that water across the roof and result in leaks elsewhere in your building – you can see a leak in your building, and the damaged membrane can be 20 feet away.
Water damaged roof insulation also has a lower R-value and can affect the uplift performance of a roof system, which is particularly dangerous in any high-wind area. When the design requires, use a vapor barrier to limit moisture drive into the system from the building interior. From the exterior, the use of a durable, high-performance membrane can help protect your investment and keep insulation dry, maximizing its useful life.
Commercial Building Roof Insulation Best Practices
When it comes to commercial building roof insulation, it pays to follow the membrane manufacturer’s recommendations and select a product well suited to the application. This will ensure the most extended life for the membrane roofing system and protect your warranty coverage.