Updated Jan 20, 2023
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Insulating your roof or attic space is going to be a necessary task in almost any climate. Doing so with high-grade insulation materials is a great way to reduce energy costs and keep your living space at a pleasant temperature year-round. Here, we’ve outlined the different types of insulation to make your choice of material easier, the positives and drawbacks of each insulation type, how much insulation costs, and how to choose the best insulation for your roof and attic.
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Once your roof assembly has been completed, you’ll have plenty of insulation options to place under the roof decking in your attic. When combined with your roofing system, these insulation options should provide varying degrees of protection from the elements. Each insulation type here has varying costs and R-values — or resistance to heat flow.
When examining your recommended R-value, you’ll have to take your local weather patterns into account, along with the existing architecture of your home. Colder climates and older construction typically require more added resistance to heat loss.
Follow this link for a full explanation of recommended R-values by region. For reference, commonly-recommended roof R-values are 30, 38, and 49, depending on the region.
Spray foam insulation is one of the most commonly used roof and attic insulation types. Unfortunately for DIYers, this insulation type requires professional installation.
This video from Inside Lighthouse is a great beginner’s guide that should help you tell the differences between the two types of spray foam:
Spray foam insulation comes in two basic types. They are:
Both spray foam insulation forms will cost between $1,500 and $1,800 before labor. These averages reflect a cost of between $0.50 and $1.50 per board-foot — that is, one square foot of roof decking covered with an inch of material.
Labor costs range between $1.50 and $5 per board foot. Assuming a roof with 1,500 square feet of space, you’ll be on the hook for $2,250 to $7,500 for labor alone.
Their different densities give open and closed cell insulation different R-values. Open-cell foam is better for warmer climates, while closed-cell is highly recommended for cold weather.
Generally speaking, spray foam insulation is one of the best options for both warm and cold climates. The application techniques used by contractors mean that this insulation fully adheres to every corner of your substrate and joists, which can eliminate the need for any kind of vapor barrier. This provides maximum efficacy when shielding your home from temperature changes.
Both roll and batt insulation come in varying thicknesses. Other common materials for this kind of blanket insulation are mineral wool, plastic fibers, and more natural fibers. The main attraction for clients is that these insulation materials are usually flame resistant and are easy to install without the benefit of a contractor.
Though made of the same material, this type of insulation comes in different cuts with varying thicknesses between 3.5 and 12 inches. Batts come in varying square or rectangular cuts, which make DIY installation easier.
Rolls come in the same range of thicknesses but are better suited for applying insulation to larger areas.
The standard R-value range for batt and roll insulation is between 2.9 and 3.8 per inch. Certain high-density fiberglass can reach R-values of 4.3 per inch, making the thickest varieties sufficient for most climates.
Fiberglass insulation is a prime candidate for many budget-conscious or DIY clients. Along with this, it offers the following benefits:
Foam board insulation is made of either polyurethane, polystyrene, or polyisocyanurate and offers a fairly high R-value for its thickness relative to other insulation types. In order to meet building codes, this type of insulation has to be coated in a half inch of gypsum sheathing or other similar fire-resistant material.
Foam board insulation is fairly reasonable but can run a little high for some clients’ tastes. It is most commonly sold in four by eight-foot boards and comes in at $0.25 to $1.50 per square foot. As a DIY option, it’s fairly easy to install due to its rigidity and the ease with which you can cut it to fit any space.
Depending on the manufacturing technique, the R-value for foam board insulation ranges between 3.6 and 5.8 per inch.
Foam board types comprise one of the more versatile insulation systems available. Benefits include the following:
Loose-fill insulation is sold in bags of loose fibers which can be made to fit nearly any gap in walls or ceilings. Though the technique for a proper application requires professional assistance — especially for more difficult-to-reach areas — it is an excellent choice for filling in space between ceiling or roof joists and wall studs to further insulate your home.
Loose-fill insulation comes in three main types. They are as follows:
This insulation is sold in large bags. Each bag can cover varying areas of space in a blanket six to seven inches thick.
Blown-in insulation has a number of applications and can decrease utility costs and heating bills long-term. Aside from being a relatively easy insulation type to install on your own, it can provide a natural noise barrier, an efficient guard against condensation, and flame-resistant shielding for your roof.
Reflective insulation is a thin tin-foil-like layer that is most widely used in hotter climates. It works by reflecting radiant heat outward — or inward on colder days. This is one of the most pliable insulation forms, making it fairly easy for DIY clients to work with.
Reflective insulation is sold in large rolls at either 24 or 48 inches in width, with total square footage ranging greatly. When purchasing 200-square-foot rolls, you’ll usually pay around $0.40 to $0.50 per foot. Buying in greater bulk can get you even lower rates.
With foil insulation usually coming in at 3/8 per inch, you’ll see an R-value of around 1.0 for most brands. Many homeowners elect to use it as a supplemental layer on hard foam insulation rather than a standalone solution for their insulation needs.
Reflective insulation is one of the easiest materials for DIYers to work with. It is effectively waterproof and totally non-toxic, which makes it a great choice.
Rather than a separate insulation technique or material, Structural Insulated Panels, or SIPs, are a fully-insulated construction material used largely for private residences. They are padded with oriented strand boards on either side of rigid foam insulation.
Costs for this form of insulation can vary greatly. Given its sturdiness and integral nature to the structure of some new-construction homes, you should expect to pay a premium regardless. The cost per square foot will depend on panel thickness, which can range between four and 13 inches.
Exact costs typically run between $10.50 and $15 per square foot, with panels sold in sizes ranging from 4’x8’ to 8’x24’.
R-value will also have a relatively wide range, which will once again be dependent on thickness. With boards of 7/16” on each side of panels, R-value can range from 13.9 at 4.5” of total thickness to 41.8 at 12.5” thick.
Structural panels have to be built into a structure to be a cost-effective and viable option for insulation. They’re fairly common in newer construction, and once in place, they can last up to 60 years. Many who have their choice of insulation types choose these for the following reasons:
Concrete block insulation refers to the process of either filling in gaps in an existing concrete wall or covering the exterior or interior surface with insulation. Using cover board on either wall is definitely the superior method between the two. Since concrete is a fairly heat-conductive material, rigid foam insulation is a far more efficient insulation technique.
Eight-inch concrete walls have a typical R-value of 2 – 2.5, which makes unfinished blocks more than suitable for basements without insulation.
Assuming foam board insulation, you’ll pay between $0.25 and $1.50 per square foot for materials alone. That said, a DIY installation is a viable option for this kind of insulation.
R-values for rigid foam insulation are listed above. When secured with foam-safe glue to concrete blocks, they form an efficient barrier for any purpose.
Spray foam insulation will have varied R-values, depending on the kind of foam used. Open-cell has an R-value of 3.7, while closed-cell foam has an R-value of 7 per inch. The benefit of this type of insulation for concrete blocks is somewhat negated by the fact that you’ll only be able to fill the cores of the blocks in question, which leaves some potential for heat conduction from exterior to interior.
Concrete block insulation is commonly seen in finished basements but is necessary for any main living space in a concrete-construction home. Concrete makes for a poor insulator on its own and will likely require a rigid foam board on the exterior or interior wall in order to make for a more energy-efficient home.
Brick is a fairly poor insulator on its own, with R-values ranging between 0.1 and 0.2 per inch. Thusly, bare brick construction will require insulation of some kind if there is no additional buffer between the interior and exterior of your home.
The most commonly used types of insulation for brick walls are the above-mentioned XPS and polyiso rigid foam materials. For actual living spaces, these insulation types will provide ample coverage.
Rigid foam will cost between $0.25 and $1.50 per square foot of material, depending on thickness and R-value.
Costs for spray foam materials alone will range between $0.50 and $1.50 per board-foot (one square foot covered by an inch of material). Additional coverage and professional application are recommended, which could cost up to $5 per square foot, depending on coverage level.
While open-cell and closed-cell spray foam insulation have varied R-values between 3.7 and 7 per inch, application ability to brick walls or within hollow bricks is fairly limited. You’ll likely have to go with rigid foam insulation, which will have R-values between 3.6 and 5.8 per inch.
Given the poor insulation qualities brick exhibits on its own, the application of extra layers will be a must to ensure proper energy conservation in your home.
To our thinking, spray foam insulation is the best option for your attic. The application process will maximize the air sealing capabilities that most insulation types promise while providing comprehensive coverage for all corners and odd spaces. You may need to hire a contractor or roofing or insulation professional to help with the application process, but the added cost and versatility of this insulation type are well worth it.
This depends entirely on the type of insulation you use. Blown-in or spray foam insulation should definitely be done by a licensed professional. They have the necessary tools to get the job done properly, as well as protection from hazardous particles which could spread through the air in the workspace. All necessary tools are easy to purchase or rent from most major hardware stores, but if you’re on the inexperienced side, you would be well-served to at least get a quote from a pro.
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Your best choice for loose-fill insulation is cellulose. With an R-value of 3.7 per inch, it will provide you with the most protection of any blown-in insulation type.
Between insulation layers and your roof decking, air gaps of 1/2” to 3/4” are recommended. When outside temperatures greatly diverge from indoor temperatures, condensation can form between the insulation and outside-facing materials. Over time, this can cause water damage or mold buildup. A large enough air gap will allow for this to dry before it causes any damage.
The typical effective lifespan of any roof insulation is 15 to 20 years. Structural panel insulation has a far longer shelf life, but separately applied insulation types are likely to degrade far quicker. You should inspect your roof insulation every 10 to 15 years to be sure of its efficacy.
Arranging for a home repair of this scale is going to be a fairly involved project. If you haven’t conducted renovations like this – either via a contractor or on your own – then it can be a bit overwhelming. At House Method, we pride ourselves on being able to take all of the guesswork out of the equation for you.
We’ve thoroughly evaluated each roofing type to make your selection process easier. Through exhaustive research into hundreds of different roofing providers throughout the United States and analyses of thousands of individual homeowner experiences, we’ve broken our roof rating system down into the following categories.
All roofs receive an aggregate rating between (0.0) and (1.0). This rating is comprised of six key evaluation criteria, which we’ve outlined below. The rating between (0.0) and (1.0) will correspond to a secondary rating out of five stars, which is displayed more visibly in our articles across this category.
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