10 Things to Consider When Buying Glass Wool Roof Insulation

Synopsis: Former FHB editor Brian Pontolilo suggests an approach to choosing insulation based on several criteria: R-value, air permeability, vapor permeability, moisture tolerance, ease of installation, global-warming potential, cost, and toxicity. Using these criteria, he profiles 12 different types of insulation.

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Choosing the most appropriate type of insulation should be part of an overall strategy of materials selection. The underlying purpose of green building is not to develop marketing brochures that will help sell 'green' houses in suburban subdivisions, but to make decisions that genuinely benefit people and the planet. This makes a strong case for finding ways to use insulation and other materials with low carbon emissions.

When I was asked to help teach a class on how to choose insulation, I knew that it would have to include examples of different ways to insulate slabs, basements, and crawlspaces; walls, ceilings, and roofs; and tricky areas like rim joists and kneewalls. I also hoped I could offer a systematic approach to evaluating products so that the folks who participated in the class could learn to determine for themselves if a particular material was right for their specific project. To do this, I started to develop a list of criteria to consider when choosing insulation. When I thought I was done, I ran it by a few colleagues and asked a few designers and builders some specific questions about how they settle on insulation in their work. I ended up with seven or so points that need to be considered when choosing insulation. Then I started to rethink my approach altogether, but we'll get to that a little bit later. First, here's the list of factors I came up with.

What is Net Carbon Emissions?

Net carbon emissions is a way to account for the climate effects of a material and is an indicator of global-warming potential. Here it is measured in kgCO2e/m2, which quantifies the carbon released as a result of producing and installing this material as a carbon dioxide'emissions equivalent. Materials with negative values store more carbon than they take to produce and install. The numbers that appear in this article are reported by Builders for Climate Action for a layer of insulation with an insulating value of R-10.

R-value

How well insulation slows heat transfer is quantified as R-value. The higher the number the better when it comes to R-value. When you see an R-value listed, it's important to know if it is the total R-value for a product or an R-value for the material, which is usually given as R-value per inch. For example, you can buy an R-13 fiberglass batt designed to be installed in a 2×4 wall, and R-13 is the total insulating value for each batt. If you are blowing loose-fill fiberglass insulation into an attic, however, the product is likely sold at around R-3 per inch. The total R-value will depend on how deep you blow the insulation, as well as its density.

Because standardized R-value testing measures all three types of heat transfer'conduction, radiation, and convection'R-value is R-value. In other words, whether it is fiberglass insulation or spray foam doesn't matter when it comes to R-value. The marketing material provided by some insulation manufacturers may try to make you think otherwise. Don't be fooled. One product may do a better job of air-sealing than another, but that has to do with air permeability, not R-value. Of course, installation matters, and your insulation will only perform as well as the installation. Ultimately, the R-values you need in an assembly will be determined by code requirements and performance goals.

Air permeability

A continuous air barrier is a key component of any high-performance home, and it's even more important than insulation for durability, energy performance, and comfort. (If air is passing through your insulation, it increases convective heat loss.) When it comes to air permeability, insulation falls into one of two basic categories: air permeable or air impermeable. You can use air-impermeable insulation as the primary air barrier in your building assembly, but that's not to say that air-impermeable insulation is always the better choice.

It's becoming very common for air-sealing to be done on the exterior of the building envelope, with taped sheathing, for example. With a well-detailed exterior air barrier, an air-permeable insulation like mineral wool will perform just fine in the walls.

There are times when an air-­impermeable insulation makes sense. One common example is the use of rigid foam to retrofit insulation from the interior at the rim joists of older homes. The rim area is prone to air leakage. So installing air-impermeable rigid foam, and sealing it in place with canned spray foam or caulk, not only increases thermal performance at the rim joist but also stops air infiltration from outside. It also keeps potentially moisture-rich interior air from reaching the sheathing and condensing (turning into water). That's where vapor permeability comes into play.

Fiberglass

Fiberglass insulation is widely available in batt and loose-fill form. Batts come in two standard widths for wood-frame construction and are commonly available with formaldehyde-free binders. Batts consist of spun glass fibers and come with or without a facing, such as kraft paper or foil. Careful installation is essential to avoid gaps that reduce effectiveness. Batts are not an air barrier and can't be used below grade.

In loose form, fiberglass can be blown onto attic floors or, in higher densities, into wall and ceiling cavities. It's available by the bag from big-box retailers. The fibers fill voids more effectively than batts, reducing air leaks, but blown-in fiberglass is not considered an air barrier. Loose-fill in an attic has DIY potential, but dense-pack application requires better equipment and more skill. Use above grade in walls, ceilings, and attics.

R-value: R-3.1 to R-4.2 per in. (batt); R-2 to R-4.2 per in. (blown), depending on density
Cost: Low
Net carbon emissions: Low (R-3.6 batt, 1.2; R-2.6 blown, 1.8)
Toxicity: Low, but wear a face mask and long sleeves to reduce skin and bronchial irritation (some brands are advertised as no-itch)
Installation: Batts and loose-fill in attics are accessible to homeowners as well as pros, but beware of sloppy work that reduces effectiveness. Dense-pack fiberglass is best left to professionals.

Cellulose

Cellulose is shredded newspaper or cardboard and is available by the bag or in batt form. There are no rigid panels. Cellulose has strong environmental credentials, and it's a favorite among many green builders because it has high recycled content. Unlike fiberglass, which has about the same R-value, cellulose sequesters carbon. It can absorb moisture from the air and then release it when the air dries out. But because it readily absorbs water, plumbing and roof leaks can go undetected. It's used as loose-fill in attics and as dense-pack and in batt form in enclosed wall and ceiling cavities. Dense-pack cellulose installed at 3.5 lb. per cu. ft. is more resistant to air leaks than fiberglass, but cellulose is not an air barrier. It can be used in above-grade applications only. DIYers can rent blowers for loose-fill, but dense-pack calls for professional tools and skills. It is typically treated with borate as a fire retardant.

R-value: R-3.2 to R-3.8 per in.
Cost: Low (somewhat more than blown-in fiberglass)
Net carbon emissions: Sequesters carbon (R-3.7 dense-pack, '1.8)
Toxicity: Low
Installation: Similar to blown-in fiberglass. DIYers can tackle loose-fill in attics, but hire a professional installer for dense-pack. Wear a face mask.

Spray foam

Available in two basic types'closed-cell and open-cell'spray polyurethane foam has some unique performance characteristics but also raises a few environmental concerns. At 2 lb. per cu. ft. (vs. 1'2 lb. per cu. ft. for open-cell foam), closed-cell foam is the denser of the two. Closed-cell foam also acts as a vapor retarder, while open-cell foam is vapor open, a difference that becomes important in some applications. Open-cell foam uses water or carbon dioxide as the blowing agent, an environmental advantage, while blowing agents in closed-cell foam remain a sore point among green builders. Newer versions of closed-cell foam use hydrofluoroolefin (HFO) blowing agents, with a relatively low global-warming potential, but older formulations use a hydrofluorocarbon (HFC) with a much higher climate impact. (Icynene has developed a medium-density, closed-cell foam that is blown with water.) While these differences are important, both open- and closed-cell foam share an ability to fill wall and ceiling cavities very effectively and are excellent air barriers. Both are expensive, especially closed-cell foam, but it comes with a higher R-value. Both types are made by mixing two components on-site as they are sprayed by the installer.

R-value: R-3.5 to R-3.6 per in. (open-cell); R-6.5 per in. (closed-cell)
Cost: High
Net carbon emissions: Moderate to very high (R-4.1 HFO-blown open-cell, 2.9; R-6.6 HFC-blown closed-cell, 23.2)
Toxicity: Stay out of the house during installation. There are reports of lingering odors and/or off-gassing that affect chemically sensitive people.
Installation: Open-cell has a much higher rate of expansion and typically is allowed to overfill cavities and be cut back when cured. Care must be taken not to apply closed-cell foam in too thick a layer, which can cause a fire. Premises should be vacated while foam is applied. Odors from closed-cell foam can linger, but properly mixed and applied insulation is inert once cured.

Vapor permeability

Air permeability and vapor permeability are connected. Vapor permeability, which is measured in perms, describes a material's ability to allow water vapor to pass through it. At above 10 perms, insulation is considered 'vapor open.' Mineral wool falls into this category, meaning that water vapor can pass through unimpeded. At 10 perms or less, insulation is considered a vapor retarder (meaning that water vapor passes through, but at different rates) in one of three classes defined by the International Residential Code (IRC):

' Class I: Less than or equal to 0.1 perm. Foil-faced rigid foam falls into this category.
' Class II: Greater than 0.1 perm but less than or equal to 1.0 perm. The IRC puts kraft-faced fiberglass batts in this range, though some may become more vapor open as humidity levels rise.
' Class III: Greater than 1.0 perm but less than or equal to 10 perms. Unfaced rigid-foam insulation generally falls into this category.

To determine if the insulation you are using has an appropriate perm rating for your project, you need to understand the vapor profile and condensing surfaces of the assembly. For example, if you are building in a cold climate, where it is advantageous to slow outward vapor drive in the winter, a kraft-faced fiberglass batt may make sense. If you were to use a low-perm exterior insulation on the same wall'say, foil-faced rigid foam'you may choose an unfaced batt so the wall could dry more readily toward the interior should it get wet.

Mike Xenakis, building performance lead at New Frameworks, a construction company in Vermont, says that prioritizing bio-based insulation like cellulose has pushed his company toward vapor-open wall assemblies. 'That means we need a robust air barrier,' he explains. 'We're typically building homes with one or less air changes per hour. We do mid-stream blower-door tests and a lot of quality control on the air barrier.'

Moisture tolerance

The most common example of when the moisture tolerance of an insulation matters is when it is used in contact with the earth or outside the building envelope, where fibrous insulation is typically not a viable choice. When insulating beneath a slab or on the outside of a basement, the most commonly used insulation types are EPS or XPS rigid foam, because they hold up to wetting. (Both can work, but many green builders avoid the high global-warming potential of XPS.) Because it is water resistant, mineral wool can also be used in these applications, though it is less common.

'I like GPS [graphite extruded polystyrene] and Rockwool under slabs,' wrote builder Travis Brungardt in an . 'But if Glavel continues to get cheaper, it's an ideal underslab insulator'especially in remote areas where access for trucks and heavy equipment is challenging.'

Another example of builders choosing insulation for its moisture tolerance is the common option of dense-pack cellulose in double-stud walls, though for different reasons. Dense-pack cellulose is a so-called hygric buffer, meaning that it can absorb, distribute, and release moisture without degradation. '[Cellulose] is an affordable material, has very low embodied energy, can be repaired, and works very well as a buffer when vapor drive spikes,' wrote Dan Kolbert in 'A Case for Double-Stud Walls' (FHB #291). 'It can hold and redistribute vapor, releasing it to the dry side, in ways that foam, fiberglass, or [mineral] wool can't.'

Installation details

There are at least as many ways to install insulation as there are insulation types. Some insulation can be installed by a homeowner or general contractor fairly well. Blown-in attic insulation comes to mind. Other types, like open- and closed-cell spray foam, require experienced professionals. In either case, it is critical to know how the material is properly installed and what prep is required.

For example, before you rent a machine and start blowing loose insulation into your attic, make sure all air-sealing work is complete, or you're wasting your time. Sometimes environmental conditions are critical. For a proper spray-foam installation, the chemical components must be warm, and the ambient and surface temperatures must fall in a specific range. If an installer tells you these things don't matter, be wary. A spray-foam installation gone wrong is not an easy thing to make right.

'We prioritize the ability to do a great job on the install with ease and comfort,' wrote Brungardt. 'Similarly, we like the ability to readily confirm proper installation. You need more than a walk-through look-around and will have to break out the IR camera if spray-foaming, dense-packing cellulose, or using faced batts.'

Expanded polystyrene

EPS is a lightweight rigid foam used in a variety of applications: as a continuous layer of insulation in exterior wall and roof assemblies to cut thermal bridging, under slabs, and on the outside of foundation walls. Unfaced EPS is vapor permeable and available in a number of densities with corresponding compressive strengths. Higher densities do better below grade. The blowing agent for EPS is pentane, a hydrocarbon. EPS does not contain hydrochlorofluorocarbons'potent greenhouse gases'and so is preferred by many green builders. EPS manufacturers in the United States have replaced a brominated flame retardant called HBCD with a polymeric retardant, which is thought to be safer. EPS's thermal performance does not degrade over time. GPS (graphite polystyrene) is an EPS variant that is infused with graphite. It has a characteristic gray color and a higher R-value than conventional EPS. It is more common in Europe than the U.S. and has lower carbon emissions than traditional EPS.

R-value: R-3.6 to R-4.2 per in. (GPS, R-4.7 per in.)
Cost: Moderate
Net carbon emissions: Moderate (Type II R-4, 6.6; GPS Type II, 4.9)
Toxicity: Low
Installation: Used in wall and roof assemblies, under slabs (at the correct density), on foundation walls, and in insulating concrete forms. Lightweight and easy to handle.

Extruded polystyrene

XPS is another common rigid foam with slightly higher R-values than EPS. One of the principal chemical differences between the two is that all XPS has until recently been made with a hydrofluorocarbon blowing agent with more than times the global-warming potential of carbon dioxide (HFC-134a). This alone steers many green builders toward another insulation choice. However, Owens Corning announced a switch to a new XPS formation that eliminates HFC-134a. XPS is not as vapor permeable as EPS (about 1 perm for an unfaced, 1-in.-thick panel), it is somewhat higher in cost, and its thermal performance declines over time ('thermal drift') as the blowing agent slowly dissipates and is replaced with air. Exactly where the R-value bottoms out is unclear, but it's estimated that XPS will decline to R-4.5 in the first 20 years, and eventually to R-4.1 or R-4.2. It is available faced and unfaced. There are three makers in the U.S.: Owens Corning, Dow, and Kingspan.

R-value: R-5 per in. (when manufactured)
Cost: Moderate
Net carbon emissions: High to extremely high (Owens Corning NGX, 14.3; conventional HFC-blown XPS, 98.7)
Toxicity: Low
Installation: Similar uses as EPS

Polyisocyanurate

Polyiso completes the trio of commonly used rigid-foam insulation materials. Because of the method used to manufacture it, it is always faced. Foil facing makes it vapor impermeable. One big difference in the field is that polyiso is not rated for ground contact, so it's never used below a slab or to insulate foundation walls from the outside. One of its principal uses is as roofing insulation. Polyiso is subject to thermal drift, with its R-value dropping from about R-6.5 per in. at the time of manufacture to about R-5.6 or R-5.7 per in. over time. Polyiso also has another quirk: Its thermal performance goes down with the temperature, from R-5.6 or R-5.7 when it's 75°F to about R-4.8 when the mercury drops to 25°F, although manufacturers are looking for ways to counter this problem. Like EPS, polyiso is blown with pentane, a compound with a relatively low global-warming potential. Polyiso is more expensive than XPS and EPS and is not recyclable.

R-value: R-6.5 when manufactured, declining to R-5.7 over time (lower in cold temperatures)
Cost: Moderate
Net carbon emissions: Moderate (5)
Toxicity: Low
Installation: Used like other foam-panel insulation materials

Wood fiber

Wood-fiber insulation comes in several forms, including rigid panels, batts, and loose material that's blown into enclosed cavities in the same manner as cellulose or fiberglass. Timber HP is the only U.S.-based manufacturer, though the company's board, batt, and loose-fill products are still being developed. Two imported brands are Steico and Gutex, both manufactured in Europe. Though imported options are expensive, wood fiber has appealing characteristics: It is manufactured from a renewable resource without petrochemicals, it has no embodied carbon, and it has low toxicity. Panels are nonstructural and vapor-open. Wood fiber is often used as a continuous layer of insulation on roofs and exterior walls. European products come in odd sizes.

R-value: R-2.7 to R-3.7 per in. (panels); R-3.9 to R-4 per in. (batts); R-3.6 to R-3.8 (blown-in)
Cost: High
Net carbon emissions: Sequesters carbon (R-3.8 batts, '1.9)
Toxicity: Very low
Installation: Loose wood fiber is handled like cellulose; panels go up like rigid foam and can remain exposed to the weather for a number of weeks without damage.

Global-warming potential

Today, every building material should be evaluated for its environmental impact. It's not always an easy equation, and including this criterion doesn't make decisions any simpler. Sometimes a better-performing material may also come with a greater climate cost. XPS rigid foam performs excellent below grade. It also has one of the highest global-warming potentials of all insulators. Cellulose has a minimal environmental impact, but you can't use it to insulate below your slab. Sometimes we can change the building assembly to make a more sustainable option work. When we can't, compromises need to be made.

Costs

Every building project has a budget, so every material choice comes with a cost; therefore, cost deserves a place on this list. It may also be the most challenging factor to discuss. First, there's the practical reason that costs vary from one region to the next. We can generalize'fiberglass is probably at the low end of the cost range all around the country; mineral wool is often a premium product. On the other hand, spray foam and cellulose costs vary widely based on how common and available they are in a given region.

The other reason it is difficult to discuss cost is because of the impact an insulation choice has on the rest of the budget. I've talked to enough designers and builders over the years to know that it's much easier to sell clients on nicer flooring or a tiled shower than on energy improvements like insulation. I've also learned that client education is an often-overlooked piece of the puzzle. If your clients understand that more or better insulation is part of a robust envelope, which means they will spend less on their mechanical system, there's a better chance that they'll spring for it. I've often been impressed when I visit high-performance homes at how much the owners know about the nuts and bolts of their house. This is usually a credit to the architect or builder who did a good job of educating them throughout the process.

'It's our duty,' says Xenakis. 'We have to help our clients understand that there are upfront costs, there are overtime costs, and there are environmental costs. We have to weigh it all, specific to each job.'

Cotton batts

Made principally from denim scraps with some additional synthetic fiber, cotton batts can be used only above grade in wall and roof assemblies. Unfaced batts are air permeable and come in oversized widths for a friction fit in framing cavities. Some installers complain it is difficult to cut and doesn't always bounce back after compression. Like other types of batt insulation, it must be fitted carefully around wires, pipes, and other obstructions in wall and ceiling cavities. It is more expensive than fiberglass and mineral wool batts, but Bonded Logic, which manufactures Ultra Touch, promotes its no-itch natural fiber content. It is treated with borate for fire resistance and includes high recycled content (80% postconsumer).

R-value: R-3.5 to R-3.7 per in.
Cost: Moderate
Net carbon emissions: Moderate (R-3.6 batt, 2.3; R-4.4 loose fill, 3.4)
Toxicity: Low
Installation: Similar to other friction-fit batts, but not as easy to trim. Manufacturers emphasize 'no itch' qualities.

Straw

Straw has extremely attractive environmental credentials. It is reclaimed agricultural waste, a raw material that is completely renewable and, regionally, widely available. It has very low toxicity, good fire resistance, and very high carbon capture. Straw mostly is used in the form of bales that are assembled into walls on-site and then finished with stucco or plaster. It's also available in panel form. EcoCocon, a European manufacturer operating in the United States as Build With Nature, offers a 15.7-in.-thick structural insulated panel with an R-value of 38. The load-bearing panels with a continuous layer of wood fiberboard insulation cost about $18 per sq. ft. (but this number includes the wall structure as well as insulation). Straw-bale construction is not common, but proponents are passionate about its advantages. It has low R-value per inch, but thick walls make up for it. Bales can be used as structural components or as infill in wood- or steel-framed structures. Straw bales are susceptible to water damage, so buildings need wide roof overhangs, careful flashing over windows and doors, and separation from moist materials. It offers high DIY potential.

R-value: R-1.4 to R-2.4 per in.
Cost: Low (bales) to high (prefabricated panels)
Net carbon emissions: Sequesters carbon (R-2.9, '14.5)
Toxicity: Very low
Installation: Straw bales can be incorporated into buildings as infill or structural components as a low-tech building method friendly to owner/builders. Straw panels are comparable to other types of structural insulated panels (SIPs).

Hemp

Hemp is another renewable agricultural material that scores well on the carbon sequester scale, second only to straw. But hemp insulation has struggled to gain a toehold in the market, and supplies of hemp insulation are spotty. A Kentucky company called Sunstrand LLC was producing R-13 batt insulation for 2×4 walls, but the company filed for Chapter 7 bankruptcy. A Quebec-based company, MEM Inc., continues to produce hemp blocks as well as sheets of hemp insulation 3-1 ' 2 in. and 5-1 ' 2 in. thick, with R-values of R-13 and R-20, respectively. The insulation is 88% hemp and 12% polyester. Hempcrete is another form of hemp insulation. It's mixed from hemp hurds (the cores of the plant), plus lime and water, and formed into blocks in steel or metal frames or tamped into moveable lifts to make larger wall sections. The low-density material is not load-bearing. It is vapor permeable. Hemp can be ordered from companies such as American Lime Technology. For more information, contact the U.S. Hemp Building Association.

R-value: R-1.2 to R-3.7 per in.
Cost: Moderate
Net carbon emissions: Sequesters carbon (R-3.7 batt, '3.1)
Toxicity: Very low
Installation: Hemp panels are installed between studs on 16-in. centers. Hempcrete blocks and wall sections can be made on-site and may have the same DIY appeal as straw-bale construction.

Cork

Manufacturers point to the strong environmental credentials of cork insulation'100% renewable, recyclable, and about as green as it gets if you don't figure in transportation from the western Mediterranean where cork oaks grow. ThermaCork, a supplier, lists panels from 1 ' 2 in. to 3 in. thick. Expanded corkboard is made from the outer bark of the trees, which reportedly suffer no harm in the harvesting process and may live to be hundreds of years old. Eco Supply Center is a U.S. distributor for ThermaCork. The company says that 95% of cork products come from Portugal and that cork insulation was once common in the United States, having even been used at the White House. It is semi'vapor permeable (2 perms at 2 in. thick).

R-value: R-3.6 to R-4.2 per in.
Cost: High
Net carbon emissions: Not available
Toxicity: Very low
Installation: Installed like other board insulation. Some versions can be used as exterior cladding, where it weathers from a chocolate brown to a concrete-like shade.

And the list goes on

I recently insulated below a basement slab with EPS rigid foam that I ordered from a company located a couple hours from where the product was manufactured. Had I not been fortunate to be emailing with designer Michael Maines, who turned me on to Branch River Plastics at the time that I needed to order the insulation, I would have used next-gen XPS from the local big-box store at a higher financial and environmental cost.

I got lucky, but availability is a real issue. If you want to use wood fiber as exterior continuous insulation, you probably can't run down the street to get it. But as Maines pointed out to me, when we are building custom homes, we have the time to do the research and source the best products for the job. Maines was the one who suggested I add 'availability' to my list of criteria for choosing insulation.

Peter Pfeiffer, principal at Barley/­Pfeiffer Architecture in Austin, Texas, brought another consideration to my attention: sound attenuation. In the hot and humid climate where most of his projects are located, he prefers a flash-and-fill insulation system, with a flash coat of closed-cell spray foam to provide R-value, vapor control, and additional air-sealing (though he specs a primary exterior air barrier at the sheathing), and a fill of dense-pack cellulose that he says can effectively hold and redistribute excess moisture created inside the house. Pfeiffer calls this a perfect system and includes the fact that it makes for a quiet interior, which is important to many urban homeowners.

There's even more to consider: What happens to a material at the end of its initial service life? Rigid foam and mineral wool, for example, can often be reused. If insulation can be left exposed'in an unfinished basement, for example'most foam plastics must be covered with something that provides a code-required fire rating. And there are health concerns for installers and folks with chemical sensitivities; at a minimum, make sure you and your installers are taking the appropriate safety precautions for whichever type of insulation you are installing, and educate your clients on the potential risks of off-gassing.

What are your priorities?

I'm wondering now if my list isn't flawed from the start. I came at the topic with efficiency and comfort top of mind. But it seems that any insulation can accomplish this. And the air-, water-, and vapor-control layers can ensure that the building enclosure is durable and tight.

I didn't create this list with an order of importance in mind. I started with the most obvious consideration (R-value) and ended with cost'which is ultimately important to the person writing the checks but has no implication on the quality of an assembly. Reviewing the list now, I am concerned that global-warming potential and human health are toward the end, where they could be interpreted as less important than the other considerations. Maybe human health and global-warming potential should be prioritized. Maybe the question shouldn't be 'How do I choose the best insulation?' but 'How do I use the most environmentally friendly insulation with the least risk to human health to create a comfortable and efficient house?'

Isn't that what's most important?

'Brian Pontolilo is a former editor at Fine Homebuilding and Green Building Advisor.

'Scott Gibson, a frequent writer for both FHB and GBA, contributed to this article.

From Fine Homebuilding #316

'Energy efficiency' is just not a phrase anymore. In the 21st century, it takes the front seat and becomes a necessity for modern construction. Whether it is commercial establishments, industrial institutions, or residential buildings, everywhere rising energy demands and utility costs are a growing concern. People are demanding solutions that not only increase thermal efficiency but are also cost-effective. Here, Roof Insulation Materials comes into play. It is not rocket science to understand that roofs are one of the most venerable parts of a building from where radiant heat can easily penetrate. Insulating roofs will result in outstanding results.

Roof insulation directly contributes to the energy efficiency. As per different studies, in cold climates roof insulation reduces the need for heating homes by 50%, and in hot climates, it reduces the dependence on air-conditioning by 20-30%. The U.S Environmental Protection Agency (EPA) stated that on average roof insulation can save up to 11% on energy requirements in residential buildings. Also, the International Energy Agency (IEA) reported that roof insulation will help in reducing carbon dioxide emissions by a considerable amount.

Geyu Energy Saving contains other products and information you need, so please check it out.

Additional resources:
Top 5 Rock Wool Products for Effective Insulation Solutions

Roof insulation is a modern solution for modern problems. It creates a barricade against the transfer of heat flow between the roof surface and the surroundings. By restricting heat exchange between the interiors of a building and the exterior environment, roof insulation promotes constant indoor temperature and reduces the dependence on electrical appliances. This results in the generation of fewer carbon footprints and lower energy utility costs. Sustainability is the by-product of using roof insulation.

In this article, we will understand what is roof insulation, how it works, the different kinds of roof insulation materials available in the market, and the benefits of using this product.

What is Roof Insulation?

Roof Insulation is a one-stop solution for enhancing the thermal efficiency of modern constructions by preventing the transfer of heat between the roof of a building and the surroundings. The materials and methods used for insulating roofs will create a barrier against radiant heat, curtailing its movement and helping to maintain desirable indoor temperatures. Whether it is a cold climate or a hot climate, roof insulation will play a crucial role in stabilizing the interior temperature. It curbs heat from escaping during cold climates and keeps heat away during hot climates. It creates protective layers around the roof surface either installed within or at the top, by restricting radiant heat from entering or going out via the roof.

The primary purpose of roof insulation is to enhance the overall thermal efficiency of a building and reduce the dependence on any artificial arrangement for stabilizing the indoor temperature. It does not create any difference whether it is a home or commercial space, roof insulation will work effectively in curbing the heat movement between the roof surface and the surroundings. It not only diminishes the consumption of excessive energy but also helps in achieving lower utility costs. Also, roof insulation will add longevity to the life of the roofing material and safeguard it from any external damage or wear and tear.

For defining the effectiveness of a roof insulation R-value is measured. R-value refers to the resistance offered by insulating material against heat transfer between the surface and the surroundings. The higher the R-value, the greater the operational competence shown by the insulating material in maintaining the interior temperature of a building and reducing dependence on external appliances.

How Roof Insulation Works?

Roof insulation is principally used to enhance the thermal efficiency of a building. It principally curtails the movement of heat and restricts energy transfer between the two surfaces. The restriction caused by roof insulation helps in maintaining the interior temperature and increases savings on energy bills.

The movement of heat takes place in three ways conduction, convection, and radiation. Roof insulation makes sure that it prevents the transfer of heat in all three mediums for comfortable indoor temperatures.
It works in the following way:

1. Conduction

Conduction refers to the transfer of heat taking place through solid materials. The heat tends to move from a hotter area to a cooler area. Therefore, when the temperature outside the building is higher than the inside heat tries to move in through the roof surface. Also in cold climates, this phenomenon gets reversed and heat tries to escape from inside to outside again via the roof.

To prevent this energy transfer, insulation materials like fiberglass, rigid boards, or foam (materials that are poor conductors of heat) are used. The cellular structure of these insulating materials confines the air within the structure and reduces heat flow. This leads to curbing the transmission of heat energy through the roof's surface to the interiors of a building also, it prevents heat from escaping the interiors of a building.

2. Convention

When the transfer of heat occurs through air movement it is called convention. Air from high-density areas moves towards low-density areas and transfers energy. When the temperature outside the building is higher, the hot air tends or rise and tries to break in through the roof surface. Proper roof insulation helps in combating this hot air and keeps it out of the building.

The roof insulation materials restrain the movement of air and reduce the effectiveness of conduction. Spray foams or loose-fill gaps create a protective covering around the roof surface and fill up all the gaps and cracks present there. They create an impenetrable covering and inhibit air from moving freely through the roof. This helps in maintaining indoor temperature, assuring that hot air remains outside the building in hot climates and inside the building in cold climates.

3. Radiation

The movement of energy from one place to another in the form of waves or particles without any medium is known as radiation. The radiant heat directly reaches the roof surface from the source (sun) and tries to break through. However, the use of insulating material like reflective insulation can prevent this transgression.

Reflective insulation materials like aluminum foil or other metallic foils reflect away the radiant heat that strikes the surface of the roof and help restrain heat gain during hot climates. These insulating materials are specially crafted to restrain radiant heat energy from penetrating through the roof of a building. When placed in attics and below the roof, they reflect away heat up to 95%, fundamentally making it impossible for radiant heat to disturb the interior temperature of a building.

Roof insulation is successful in curtailing the transfer of heat through all three modes. Different materials in different situations can be used for effective results and operational efficiency. Whether it is conduction, convection, or radiation, roof insulation is capable of protecting modern constructions from all these thermal threats.

Types of Roof Insulation Materials

Different roof insulation materials have distinct advantages and properties. Before selecting an insulating material it is imperative to understand its overall properties and match it with your needs.
Types of Roof insulation materials:

Fiberglass Insulation:

R-value: R-2.9 to R-3.8 per inch

Fiberglass insulation comes in a variety of forms. Whether it is batt or roll form, it is one of the best choices for insulating house and commercial roofs. What makes this product so effective against heat flow is its manufacturing. It is made up of woven glass fibers packed tightly together. This composition makes it effective for thermal insulation. For covering up loose spaces and cavities and insulating rafts, and joists, fiberglass insulation is the right choice. It is flexible and installed easily.

Advantages:

• It is fire-resistant and non-corrosive.
• It is cost-effective easily recycled is environment-friendly.
• It restricts moisture accumulation around the insulated surface.

Expanded Polystyrene (EPS) Insulation:

R-value: R-3.3 to R-4.4 per inch

Expanded Polystyrene (EPS) is a product made up of solid polystyrene pellets. The polystyrene beads make it lightweight and make it recyclable. This product is suitable for use in constructions where extensive strength and longevity are required. As it is easy to install and flexible it is suitable for use to insulate walls, roofs, and floors. However, due to its structure, it is not very effective against moisture.

Advantages:

• It resists corrosion and offers strength to the insulated surface.
• It is cost-effective and easy to install.
• It is fire-resistance

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Polyisocyanurate (POCYISO) Insulation:

R-value: R-6.5 to R-8 per inch

Polyisocyanurate insulation is available in a variety of designs and thicknesses. This product is highly efficient for thermal energy requirements and adaptable to different scenarios. Popular as a modern energy-efficient solution, it is widely used in different constructions. It is specially designed to bridge thermal gaps generated during the construction process and enhance the overall thermal performance of a building. Due to its rigidness, it is a good fit for resisting air and moisture infiltration and for enhancing its capabilities it also comes with foil layering.

Advantages:

• It is easy to handle, durable, and easily customized as per specific needs.
• It is very efficient against heat flow due to its high R-value.
• It is ideal for use in different places, even on flat roofs.

Spray Foam Insulation:

R-value: R-3.6 to R-3.9 per inch

Spray foam insulation comes in two varieties one is closed-cell insulation material and the second is open-cell insulation material. The open-cell spray foam insulation is flexible and light in weight. On the other hand close-cell spray insulation is heavier due to its density. It also possesses a high R-value. However, both products are good for insulating roofs as they are effective in sealing air gaps and moisture infiltration. The spray foam insulation is applied in the liquid foam over the surface and it expands into solid and foams the covering. For resisting heat flow and moisture closed-cell material is more effective while open-cell can be used for sound insulation.

Advantages:

• It is the perfect fit for odd spaces where the gap is very tight.
• It is durable and light-weight
• It has a higher R-value

Reflective Foil Insulation:

R-value: R-3 to R-17 per inch

Reflective foil insulation reflects away the radiant heat by creating a barrier against the radiant heat movement. It comprises aluminum foil, polypropylene, thermo foam, etc. The metallic foil is sandwiched between layers of low-conductive materials and put together using a specialized adhesive. It helps in trapping air and reflects away heat. Due to its availability in various thicknesses and sizes, it offers a comprehensive solution for insulating roofs and tight gaps.

Advantages:

• It is lightweight and easy to use. Appropriate for insulating attics, floors, and walls.
• It is cost-effective and easy to install.
• It requires low maintenance.

Cellulose Insulation:

R-value: R-3.5 to R-3.8 per inch

When recycled papers are treated with fire-retardant and added with chemicals, cellulose insulation material comes into existence. This environment-friendly and sustainable insulating material consists of high thermal efficiency and resistance against heat flow. Due to its composition, it is appropriate to use in loose-fill spaces like attics, walls, floors, etc. Surfaces surrounded by some kind of obstruction can be easily covered by this product.

Advantages:

• It is environment-friendly and sustainable insulating material
• It offers high thermal performance.
• It is easy to use and install.

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Structural Insulated Panels:

R-value: R-5 to R-7 per inch

Structural Insulated Panels are modern solutions for insulating walls, roofs, and floors. They consist of high thermal performance, exceptional air-tight coverage, durability, and strength. They are made up of pieces of foam placed between two boards for insulation. The closed-cell polyurethane or expanded polystyrene foam offers a rigid structure and provides excellent heat resistance and flexibility. Easy to customize as per need, structural insulated panels are available in different thicknesses. They are suitable for use in residential, commercial, and industrial establishments.

Advantages:

• It is easy to customize and available in different designs.
• It is cost-effective and sustainable.
• It shows high durability and heat resistance.

Key Factors to Consider When Choosing Roof Insulation

Choosing the right insulation material can make a hell of a difference. It not only increases the overall thermal performance of a building but perfectly aligns with your insulation needs. There are certain factors one must keep in mind before selecting roof insulation material. Whether it is climate conditions, budget, or sustainability of a material all these factors are crucial in determining what is right for thermal requirements.
Factors to bear in mind while choosing roof insulation material:

Climate and Weather conditions

Climate and weather conditions directly affect the outcome of an insulating material. In the winter season building is required to hold warm air inside for better heating effect. Here, insulating material with a higher R-value is beneficial because it decreases heat loss. In summer, when keeping heat away from the interiors of a building is necessary then insulating materials that reflect away the radiant heat will be more favorable.

R-value requirements

The R-value refers to the measurement of resistance caused by an insulating material against heat flow. The R-value for each construction and climate is different and that is why different insulating materials are required. It is imperative to analyze the local needs for insulation and choose the material according to it. However, the higher the R-value, the greater the performance of an insulating material.

Budget

Different insulation materials will cost different in the market. From high price insulating materials like aluminum foil to low price materials like fiberglass are present. Decide which material is the best fit for you as per your financial status as well as how much energy consumption cost it saves you in the future.

Installation Methods

Installation of roof insulation depends on the material to material. Some materials are very easy to install, while some need expert guidance for installation. For example, batts, rolls, or bubble wrap can be installed easily without any expertise. On the other hand, spray form or rigid foam requires experts for proper installation. Whether installation of insulation material requires professional help or not, impacts the overall cost of the project.

Sustainability

With the rise in sustainable living, people are demanding sustainable solutions for insulating roofs. Materials like fiberglass, mineral wool, spray foam insulation, etc. are the perfect fit in the domain. Also, materials made up of cotton or cellulose are the right choice as sustainable materials for insulating roofs. Make sure to use those materials that add up to the environmental protection.

Benefits of Proper Roof Insulation

Roof insulation not only helps you increase energy efficiency but also enhances your overall comfort level. There are several benefits of proper roof insulation.

Energy Efficiency and Cost savings

Roof insulation offers a protective layer of thermal blockade against potential heat loss and gain. It helps in maintaining the interior temperature of a building and reduces dependence on the air conditioning or heating systems for the same. This reduction in the application of appliances will lead to substantial savings over energy utility costs benefitted with extra savings.

Enhanced Comfort

Roof insulation curtails the radiant heat movement, creates barricading around the roof surface, and restricts energy exchange. This overall operation leads to comfortable indoor temperatures for living and workspaces. Irrespective of climate, roof insulation helps maintain interior temperatures comfortable for living and working that is cooler in summer and warmer in winter.

Environmental Impact

Insulating roofs with environment-friendly material will result in lesser greenhouse gas emissions and reduced energy consumption. Proper implementation of roof insulation leads to lower energy bills and curtails unnecessary dependence on electric appliances for maintaining temperature. This contributes to a greener and more sustainable environment.

Soundproofing

Roof insulation not only creates a barrier against heat flow but also restricts unwarranted sounds and establishes a sound barricade against outside noise. Buildings especially residential located in busy areas will be the most benefitted with this. This feature of roof insulation will help you enjoy peace and tranquillity without any extra cost.

Prolonging Roof Life

It is not only the protection against the heat flow that a building requires but protection of its roofing material is also desirable. Roof insulation adds to the life of roofing material and protects it from damages caused by the external environment. This protective coating defends roofing material from unwarranted expansion and contraction caused by changes in climate-enhancing material life.

Conclusion

When it comes to thermal efficiency and energy savings, insulation plays a vital role in providing environment-friendly and sustainable solutions. Roof insulation is not an exception, creating level field ground for modern constructions competing against unwarranted heat flow and energy consumption.

Stepping up for roof insulation will bring you exceptional results leading to extra savings on energy utility costs, comfortable indoor temperatures, and sustainable and thermal energy-efficient living.

However, choosing the right insulation material is not easy. There are a variety of factors one must bear in mind before selecting the perfect fit. Climate, budget, sustainability, and installation method play essential roles in deciding which roof insulation material is a good fit. Roof insulation not only protects you from external temperature interference but also adds longevity to the roofing material increasing its life span.

FAQ

1. What is the Best Insulation for a Roof?

There are a variety of insulation materials available for insulating roofs. You can opt from all these as per your needs, climate conditions, and budget. Insulation materials like fiberglass, reflective insulation, spray foam insulation, etc. provide good thermal efficiency and durability.

2. How long does Roof Insulation Last?

The life of roof insulation material depends on different factors like material used in its manufacturing, climate conditions, installation method opted, and nature of the surface where it is applied. In normal circumstances, a roof installation material lasts for 20 to 40 years. If appropriate maintenance is provided it can exist for more years.

3. Can I Install Roof Insulation Myself?

The answer to this question is yes, you can install roof insulation yourself. There are insulation materials available in the market that do not require professional help for installation. Materials like fiberglass or reflective installation can be installed without any external help.

4. What is the R-value, and Why is it Important?

R-value measures resistance offered by insulating material against the heat flow. The higher the R-value, the greater the thermal efficiency of a material.

5. Is Roof Insulation Worth the Investment?

Investing in roof insulation is worth it. It offers a variety of benefits and makes living comfortable. Whether it is protection against unwarranted heat flow or reducing dependence on electrical appliances, roof insulation does all this and helps in curtailing energy utility costs for living. It also offers durability to roofing material and increases its overall lifespan by several years, reducing the cost of maintenance.

6. How does Roof Insulation Help with Energy Savings?

Roof insulation creates a barrier against heat flow, resulting in less transfer of energy and constant indoor temperature. This ultimately reduces the dependence on appliances for maintaining the desirable indoor temperature and saves on energy consumption and bills.

7. What are the Most Eco-friendly Roof Insulation Options?

Roof insulation materials like glass wool, polyester, cellulose, sheep's wool, earth wool, etc. are some of the options that can be used as eco-friendly roof insulation materials. They are not only sustainable but also biodegradable.

Want more information on Glass Wool Roof Insulation? Feel free to contact us.