Insulation stays out of sight, but when you’re expanding your building or installing a new roof, it should be top of mind. Facilities professionals who are new to the field or are taking on their first expansion project are facing a steep learning curve.
However, there are a few key facts that apply to every insulation project. One of the most important is whether your project meets or exceeds code requirements. Your local code sets out minimum insulation requirements for your roof and walls. Going beyond code requirements can make a dent in your energy consumption by keeping heat from transferring where it shouldn’t.
Here are the basics that new facilities managers need to know to investigate the best insulation material for walls and roofs.
How Energy Codes Classify Insulation
The International Energy Conservation Code and ASHRAE Standard 90.1, the two standards on which most jurisdictions’ energy codes are based, set out three classifications for roof types and four for walls.
- Roofs: insulation above deck, metal buildings, attic and other
- Walls: mass, metal building, steel-framed, wood-framed
Each one has its own baseline requirements for the thermal envelope—the combination of the roof, walls, slabs and other components that keep heat from moving between the outside and inside of your building.
Requirements may vary depending on which climate zone your building is located in and your conditioning needs. At a minimum, your walls and roof will have to deliver a certain R-value (a measurement of how well an insulating material resists heat flow).
“The key locations for insulation are wall cavities that aren’t taken up by windows—where there’s not glazing, you’ll have insulation in the wall systems,” explains Charlie Haack, director of technical services for the North American Insulation Manufacturers Association (NAIMA).
“For ceilings, typically on flat roofs you need something a little more resilient, so depending on the structure of the building, a flat roof will use something like rock wool or a foam board. If you have a pitched roof, the most common application is fiberglass. It will be hand-blown just like a house, but it’s a larger structure. Metal buildings are built a little differently—you’re able to use fiberglass insulation at the roof and in the walls, and they’ll have insulation under the roof deck,” he continues.
Insulation Types
Upcycled and renewable materials are gaining popularity as insulation materials, including denim, rigid cork and natural wool. But most roofing projects will feature one of these three common insulation types.
Batt and blanket insulations
These flexible insulation products come in pieces (batts) or rolls (blankets). They include popular insulation products like fiberglass and mineral wool.
[On topic: 7 Green Insulation Types for New and Existing Buildings]
Rigid foam board insulation
Like the name implies, these are rigid pieces of insulation that are cut into board shapes or, in some cases, molded into the shape needed for a special application. Common insulation types for rigid foam board insulation include extruded polystyrene insulation (XPS), expanded polystyrene (EPS) and polyisocyanurate, a type of insulation made of rigid foam board sandwiched between two facers, such as paper and fiberglass.
Spray foam
Spray polyurethane foam insulation goes on in a liquid form and expands to fill the area where it’s applied. Spray polyurethane foam is useful for creating continuous insulation with no holes or leaks.
“The best insulation material for your facility is going to boil down to code requirements and climate zones,” explains Tom Robertson, business unit manager for wall insulation at Atlas Roofing Corporation.
“As you need more R-value on your building, you have to start thinking, ‘If I keep putting thicker and thicker insulation onto these buildings in New England, what does that mean for the claddings that I have to attach after I attach that insulation?’ It means they move further and further from the structural framework of the building, so they’re harder to install with all that weight hanging further outbound of the building itself. People have a preference for insulation with higher R-values per inch as you move north specifically for that reason,” says Robertson.
How to Find the Best Insulation Material
Choosing the best insulation material for your building requires an understanding of the role you need the insulation to play. The R-value of the finished assembly is the most important, but the decision around R-value can manifest itself in different ways.
“The various types of insulation have widely ranging R-values,” says Robertson. “That’s usually a matter of cost, or it might be a matter of how much insulation I want to buy. If I have an R-value target, do I use a less expensive insulation and more of it, or do I use a more expensive insulation and less of it?”
[Related: 3 Vital Roles of Roofing Insulation]
Your decision might also include the following six questions:
1. How does the insulation handle water from the outside?
2. Can the insulation perform as an air barrier if your building needs one?
3. Does your code or location dictate the use of a vapor barrier? If so, does the insulation serve that purpose? “For example, an EPS product is a very vapor-open product. A foil-faced polyiso is a vapor-closed product,” Robertson says. “One or the other of those might be the right way to go for you.”
4. What greenhouse gas emissions were released during the manufacturing of the insulation? “Almost all of our manufacturers have Environmental Product Descriptions that list emissions,” Haack says.
5. How easy is it to install the insulation?
6. How much does it cost?
“The No. 1 thing you’re choosing here is what you’re going to spend on energy in the coming years,” Robertson says. “A lot of people overlook R-value. We get caught up in whether it manages vapor or fire, but the first thing it’s got to do is insulate. Insulate the building first, then make sure the insulation you’ve chosen is going to meet the code requirements for fire performance – and they probably all will.
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“To me, it’s baffling how many people today are making poor insulation choices because they’re distracted by other performance characteristics that are also met by the other insulations they have to choose from,” adds Robertson. “There are no insulations being sold onto the market today that can’t be put into a building in a code-compliant construction.”
Many factors will affect your final insulation choice. One thing is certain, however – there’s no single best insulation material out there. The best insulation material for your facility will have a reasonably high R-value for your area and account for code requirements, local weather patterns, cost and your organization’s own priorities for insulation materials. Once you understand what you need the insulation to do, you’ll be better equipped to specify the right material.
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