A Complete Guide to Home Insulation
Installing insulation at home is the most economical and effective method to reduce heating costs in winter and cooling costs in summer. Insulation materials help maintain comfort, control humidity, and improve indoor climate.
Insulation can protect your home throughout the year from high heating and cooling expenses, while also ensuring comfort, controlling humidity, and enhancing the indoor environment. It can also act as a sound barrier between rooms and resist external noise.
The Complete Guide to Residential Insulation offers excellent insulation material choices and recommendations for selecting the most suitable insulation for your home. By using the comprehensive guide above or continuing to read, you will learn the best methods to save energy and block cold drafts!
Insulation is a crucial component of any modern energy-efficient home, offering numerous economic, environmental, and personal benefits. Learn more about how residential insulation works, the most important insulation areas in a home, the types of available insulation materials, and what to consider when deciding on insulation.
What is residential insulation, and why is it essential?
In simple terms, insulation is a barrier between the inside and outside of a house that prevents the flow of air.
In other words, insulation helps keep cold air inside during summer and warm air inside during winter. This means that a poorly insulated house will struggle to maintain warmth or coolness, leading to high heating costs.
A fully insulated home allows you and your family to enjoy the most comfortable climate throughout the year.
How residential insulation works
Residential insulation is a material that restricts the flow of heat within a home. Heat flow involves three different processes:
This is the way heat spreads through materials, caused by temperature differences. For example, when you touch a bowl containing hot food, it is likely to feel warm.
Convection is the movement of heat within liquids and gases due to differences in density. For instance, hot air rises because its density is lower than that of cold air.
Radiation occurs when heat is transferred in wave-like forms and can heat any object it is absorbed by. We experience this daily under sunlight.
Residential insulation primarily works by limiting heat conduction, which also helps reduce convection within the home. Regardless of the type of heat transfer insulation aims to prevent, all insulation materials can restrict heat flow.
Areas in a house that most need insulation
Certain common areas in every house require insulation to maximize energy efficiency. These areas include:
The attic is the most critical area that needs insulation since without attic insulation, warm air can escape, and cold air can enter. This leads to increased costs and energy wastage.
Heat rises, meaning in winter, all the energy you put into keeping the house warm will escape upwards. The same happens in summer, with rooms upstairs becoming increasingly hot, requiring additional cooling to match the lower floors.
Though heat is less likely to escape downward, an uninsulated basement can still cause the heating system to work harder than necessary. Additionally, basement insulation helps prevent the area from becoming chilly and damp.
External wall insulation is crucial, as heat can quickly dissipate if the outside is cold and windy. Internal walls can also be insulated, especially if you want different rooms to maintain distinct temperatures.
Similar to the basement, insulating floors helps prevent heat from seeping out during winter.
What types of insulation are available?
As mentioned earlier, the loft is the most important part of a home to insulate, and there are various types of insulation available for loft spaces. It’s worth noting that it’s not uncommon to have a mix of these options in order to optimize the energy efficiency of your home.
Blanket insulation is the most common type of attic insulation and is available in strips and rolls. It is made from flexible fibres such as glass fibre, mineral wool, plastic fibres or natural fibres such as wool.
Spray Polyurethane Foam (SPF)
This is a two-component mixture of isocyanates and polyols, which combine to form an expanding foam that is used to fill wall voids, roof tiles, or voids around blanket or foam board insulation.
These solid panels are usually made of polystyrene, polyisocyanurate or polyurethane and are easy to cut and install. They are suitable for exterior walls and attics and are often used to insulate structural components such as studs.
Things to keep in mind when choosing residential insulation
The type of insulation you use for your home depends on a number of factors, but whether it’s blanket, foam or something else entirely, there are a few things you should consider.
The first is the R-value of the residential insulation. This is a measure of how well a material stops the flow of heat, and the higher the number, the better the insulation.The R-value depends on the type and thickness of the material. People who live in colder climates should choose insulation with a higher R-value. See the ENERGY STAR website or Natural Resources Canada for detailed recommendations on the R-value for your area.
As mentioned earlier, the type of insulation is important, so this is something you need to consider. Fibreglass is common, but can cause problems in exposed areas and has significant environmental costs. Natural fibres such as wool, on the other hand, are an environmentally friendly alternative, but of course have their own problems. When looking for home insulation, decide what’s most important to you.
How Much Does Home Insulation Cost?
While the initial outlay for home insulation can be high, once it’s installed, you can save a great deal of money. In fact, the U.S. Environmental Protection Agency estimates that homes can save an average of 15 percent per year on heating and cooling costs when insulation is added to the floors of attics, basements, and crawlspaces, and when homes are air-sealed.
In addition, government agencies and energy providers often offer incentives for insulation and broader home improvement incentives to offset the initial cost. These incentives include regional rebates and federal programmes.
What are the main additional benefits of residential insulation?
As we said earlier, a fully insulated home is more likely to maintain optimal temperatures all year round, whether you’re keeping heat in during the winter or dissipating it in the summer.
Home insulation is one of the easiest ways to make your home more sustainable and climate-friendly. By reducing heat loss from your home, you’ll be able to use less energy to heat it, which can help reduce your carbon footprint and utility bills.
In addition, insulation is often one of the most cost-effective ways to improve the sustainability of your home. The cost of installation depends on the type of insulation your home requires, but the payback is high compared to the initial cost. For example, fully insulating your walls, roof and floors could save you up to £850 a year on your utility bills. So it’s definitely worth saving where you can.
There are also a number of energy saving schemes available for people to use to get no-cost or part-funded insulation. So make sure you check out what options are available.
Is home insulation worth it?
Used in conjunction with an efficient heating system, home insulation can save energy, CO2 emissions and money while providing a more comfortable living environment. Add to this the many financial incentives available to help homeowners with installations, and there’s little reason why you shouldn’t insulate your home.
To find out more about how our modern heating systems complement home insulation, contact us today to discuss your options and how we can help keep your system running at its best with regular maintenance.
When insulating your home, you have a wide range of insulation materials to choose from. To choose the best type of insulation, you should first determine the following:
Where you want or need to install/add insulation
The recommended R-value for the area you want to insulate.
Installation of the insulation
The maximum thermal performance or R-value of an insulation depends greatly on proper installation. Homeowners can install certain types of insulation, particularly blankets, boards, and materials that can be poured in place. (Liquid foam insulation can be poured, but requires professional installation). Other types require professional installation.
When hiring a certified professional installer, you should
Ask several contractors for written cost estimates of the R-value you need, and don’t be surprised if installation quotes for a given R-value vary by more than two times.
Ask contractors about their experience in installing the products you are considering. Installation can have a significant impact on the performance of the insulation.
Also ask the contractor about their air sealing services and costs, as it’s best to seal air leaks before installing insulation.
To assess the installation of the blankets, measure the thickness of the blankets and check for gaps between the blankets and between the blankets and the framing. Also check that the insulation fits snugly against building components that penetrate the insulation, such as electrical boxes. To evaluate sprayed or blown-in insulation, measure the depth of the insulation and check for gaps in the covering.
If you choose to install insulation yourself, carefully follow the manufacturer’s instructions and safety precautions, and check local building and fire codes. Do-it-yourself instructions are available from the Fibreglass and Mineral Wool trade organisations. The Cellulose Industry Organisation recommends hiring a professional, but if qualified installers are not available in your area, or if you feel you can do the job yourself, you can also obtain instructions from the manufacturer.
The table below summarises most of the available insulation materials.
Blankets Strips and rolls of insulation
Blanket insulation is the most common and widely used type of insulation and comes in the form of a bar or roll. It consists of flexible fibres, most commonly glass fibre. You can also find block and roll insulation made from mineral wool (rock wool and slag wool), plastic fibres and natural fibres such as cotton and sheep’s wool. Find out more about these insulation materials.
Insulation batts and rolls are available in widths to fit the standard spacing of studs, attic trusses or rafters, and floor joists: 2-inch x 4-inch walls can accommodate R-13 or R-15 insulation batts; 2-inch x 6-inch walls can use R-19 or R-21 products. Continuous rolls can be hand cut and trimmed. They are available with or without a top layer. Manufacturers often add a top layer (e.g., kraft paper, foil kraft paper, or vinyl top layer) as a vapour and/or air barrier. Insulation blankets with special flame retardant facings are available in a variety of widths for basement walls and other areas where insulation is exposed. The top layer also helps facilitate handling and fastening during installation.
Contact the manufacturer and/or your local building supplier to determine the actual thickness, R-value and cost of fibreglass blankets and fibreglass batts.
Concrete Block Insulation
Concrete blocks are used to build home foundations and walls, and there are several ways to insulate them. If the wall core is not filled with reinforcing steel and concrete for structural reasons, it can be filled with an insulating material, which will increase the average R-value of the wall. However, field studies and computer simulations have shown that no amount of fuel is saved by any type of wall core filling because heat is easily conducted through the solid portion of the wall.
It is more effective to install insulation on the exterior or interior block surfaces of foundation walls. Installing insulation on exterior walls has the added benefit of moderating interior temperatures by keeping the thermal mass of the blocks within a conditioned space.
Some manufacturers incorporate polystyrene beads into concrete blocks, while others produce concrete blocks into which rigid foam can be inserted.
In the United States, two types of solid precast autoclaved concrete blocks are currently available: autoclaved aerated concrete (AAC) and autoclaved cellular concrete (ACC). This material contains about 80 per cent air by volume and has been commonly used in Europe since the late 1940s. Autoclaved concrete has ten times the thermal insulation value of conventional concrete. The blocks are large and lightweight and can be easily sawn, nailed and moulded with ordinary tools. This material absorbs water easily and therefore needs to be protected from moisture. Precast ACC uses fly ash instead of high silica sand, which is what sets it apart from AAC. Fly ash is the waste ash from burning coal in power plants.
Hollow units made using a mixture of concrete and wood chips are also available. They are installed by stacking the units without mortar (dry stacking) and then filling the hollow units with concrete and structural steel. A potential problem with this type of wall is the vulnerability of the wood to moisture and insects.
Concrete block walls are usually insulated or constructed with insulated concrete masonry blocks in new homes or extensive renovations. Block walls in existing homes can be insulated from the inside. For more information on products commonly used to insulate concrete block, visit Insulation.
Foam Board or Rigid Foam
Foam boards (rigid insulation boards) can be used to insulate almost any part of a home from the roof to the foundation. They are very effective in special applications such as exterior wall sheathing, interior basement wall sheathing, and attic hatches. They have good thermal resistance (up to two times higher than most other insulation materials of the same thickness) and reduce heat transfer through structural members such as wood and steel studs. The most common materials used to make foam panels include polystyrene, polyisocyanurate (polyisocyanurate) and polyurethane.
Insulated Concrete Forms
Insulated concrete forms (ICFs) are basically formwork for poured concrete walls that are retained as part of the wall assembly. This system gives the wall a high thermal resistance, typically around R-20. Although ICF homes are built with concrete, they look no different than traditional stick-built homes.
ICF systems consist of interconnected foam panels or interlocking hollow foam insulation blocks. The foam panels are held together with plastic ties. In addition to the foam panels, steel rods (rebar) can be added for reinforcement before the concrete is poured. When foam blocks are used, steel bars are often used within the hollow blocks to reinforce the walls.
The foam webbing around the concrete-filled core of foam blocks can easily get into insects and groundwater. To prevent these problems, some manufacturers produce insecticide-treated foam blocks and promote waterproofing methods. Installation of an ICF system requires an experienced contractor who can be contacted through the Insulated Concrete Forms Association.
Loose-fill insulation and blown-in insulation
Loose-fill insulation consists of small particles of fibre, foam or other materials. These small particles form insulation that can be adapted to any space without affecting the structure or finishes. This compliance makes loose-fill insulation ideal for remodelling and in areas where it is difficult to install other types of insulation.
The most commonly used loose-fill insulation materials include cellulose, fibreglass and mineral wool (rock or slag wool). All of these materials are produced from recycled waste materials. Cellulose is mainly made from recycled newsprint. Most glass fibre products contain between 40% and 60% recycled glass. Mineral wool is usually made from 75 per cent post-industrial recycled material.
Some less common loose-fill insulation materials include polystyrene beads and perlite. Loose-fill insulation can be installed in both enclosed cavities, such as walls, and in unenclosed spaces, such as attics. Cellulose, fibreglass and rockwool are usually blown-filled by experienced installers to achieve the correct density and R-value. Polystyrene beads, vermiculite and perlite are usually poured.
The Federal Trade Commission has issued the “Trade Regulation Rule on Labelling and Advertising of Residential Insulation” (16 CFR Part 460). The Commission issued the R-value rule to prohibit specific unfair or deceptive acts or practices on an industry-wide basis. The rule requires manufacturers and others who sell home insulation to determine and disclose the R-value of each product and related information (e.g., thickness, area covered per package) on package labels and manufacturer fact sheets. R-value ratings vary for different types and forms of home insulation and for products of the same type and form.
For loose-fill insulation, each manufacturer must determine the R-value of its product at a fixed density and produce coverage charts showing the minimum fixed thickness, minimum weight per square foot, and area covered per bag for various total R-values.
This is because as the installed thickness of loose-fill insulation increases, its settling density also increases due to compression of the insulation under its own weight. Therefore, the R-value of loose-fill insulation does not change proportionally with increasing thickness. The manufacturer’s coverage table specifies the number of bags of insulation required per square foot of coverage area, the maximum area to be covered by one bag of insulation, the minimum weight of installed insulation per square foot, and the initial thickness and settling thickness of insulation required to achieve a specific R-value.
Radiant Barrier and Reflective Insulation Systems
Unlike most common insulation systems, which block conductive and convective heat flow, radiant barriers and reflective insulation systems reflect radiant heat. Radiant barriers are installed in homes (usually attics) primarily to reduce heat gain during the summer months, thus helping to reduce cooling costs. Reflective insulation incorporates a reflective surface – usually aluminium foil – into the insulation system, which can include a variety of backings such as kraft paper, plastic film, polyethylene bubbles or cardboard, as well as thermal insulation.
Radiant heat travels in a straight line from any surface, heating any solid that absorbs its energy. When the sun heats a roof, it is primarily the sun’s radiant energy that heats the roof. Most of the heat is conducted through the roofing material to the attic side of the roof. The hot roofing material radiates the heat gained to cooler attic surfaces, including ventilation ducts and attic floors. A radiant barrier reduces radiant heat transfer from the underside of the roof to other attic surfaces. To be effective, it must face a larger air space.
Radiant barriers are more effective in hot climates, especially when cooling air ducts are located in the attic. Some studies have shown that the use of radiant barriers in warm, sunny climates can reduce cooling costs by 5-10%. A smaller air conditioning system can even be used when heat gain is reduced. However, in cooler climates, it is often more cost-effective to install more insulation.
Rigid Fibreboard Insulation
Rigid fibre or fibreboard insulation consists of fibreglass or mineral wool material and is primarily used to insulate air ducts in homes. This material is also used when insulation that can withstand high temperatures is needed. These products are available in thicknesses ranging from 1 inch to 2.5 inches.
Installation of air ducts is usually done by HVAC contractors who fabricate the insulation in their shops or on the job site. On the outside surface of the air duct, they can attach the insulation to welded pins and then secure it with quick clamps or washers. They can also use special weld pins with integral lock washers. The unfaced boards can then be finished with reinforced insulating cement, canvas or weatherproof mastic. The panels can be installed in the same way, with the joints between the boards sealed with pressure-sensitive tape or fibreglass cloth and mastic.
Spray Foam and Foam-in-Place Insulation
Liquid foam insulation can be sprayed, foamed in place, injected or poured. Foamed-in-place insulation can be blown into walls, attic surfaces or under floors to insulate and reduce air leakage. Some installations have higher R-values than traditional strip insulation for the same thickness and can fill even the smallest cavities to create an effective air barrier. You can use small pressurised tanks of cast-in-place foam insulation to reduce air leakage in holes and cracks, such as window and door frames, electrical and plumbing penetrations.
Types of Foam Insulation
Most foams today use blowing agents that do not use chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which are harmful to the earth’s ozone layer.
There are two types of cast-in-place foam insulation: closed-cell and open-cell. Both types of foam are typically made from polyurethane. Closed-cell foam has dense cells that are closed and filled with gas, which helps the foam expand and fill the space around it. Open-cell foam has lower density cells and is filled with air, which gives the insulation a spongy texture.
Which type of insulation you should choose depends on how you use it and your budget. While closed-cell foam has a higher R-value and is more resistant to moisture and air leaks, this material is denser and more expensive. Open-cell foam is lighter and cheaper, but should not be used below grade because it will absorb water. Consult a professional insulation installer to determine which type of insulation is best for you.
Other available foam insulation materials include
Some of the less common types include ice-yne foam and terpolymer foam. Ice-nyne foam is the most versatile as it can be both sprayed and injected. It also has good resistance to air and water intrusion. Tricopolymer foam is a water-soluble foam that can be injected into wall cavities. It has excellent fire and air intrusion resistance.
Liquid foam insulation combined with a blowing agent can be sprayed using small spray containers or in large quantities as a pressure spray (foamed-in-place) product. Both types expand and harden as the mixture cures. They also adapt to the shape of the cavity, filling and sealing it completely.
Slow curing liquid foams are also available. These foams flow over obstructions before expanding and curing and are commonly used in empty wall cavities in existing buildings. There are also liquid foams that can be poured from containers.
Installation of most types of liquid foam insulation requires special equipment and certification and should only be done by experienced installers. Once installation is complete, all foam materials must be covered with a layer of approved insulation with fire resistance equivalent to one-half inch gypsum board. In addition, some building codes do not recognise spray foam insulation as a vapour barrier, so additional vapour barriers may be required for installation.
Foam insulation products and installation costs are typically higher than traditional wadded insulation. However, foam insulation has a higher R-value and creates an air barrier, which eliminates some of the other costs and work associated with weatherising a home, such as caulking, using housewrap materials and vapour barriers, and taping seams. When building a new home, this insulation can also help save money by reducing construction time and the number of specialised contractors.
Structural Insulated Panels
Structural Insulated Panels (SIPs) are prefabricated insulated structural elements that can be used in building walls, ceilings, floors and roofs. They provide superior and more uniform insulation than more traditional building methods (studs or ‘stick framing’) and can save between 12 and 14 per cent of energy. When properly installed, SIPs can also improve the air tightness of a home, making it more energy efficient, quieter and more comfortable.
SIP not only has a high R-value, it also has a high strength-to-weight ratio SIP typically consists of 4- to 8-inch-thick foam board insulation sandwiched between two sheets of oriented strand board (OSB) or other structural surfacing materials. Manufacturers can often customise exterior and interior facing materials to meet customer requirements. The face layer is glued to the foam core, and the panels are then pressed or placed in a vacuum to bond the cladding panels to the core.
A wide range of sizes of laminate can be produced. Some manufacturers produce panels as large as 8 x 24 feet that require a crane to erect.
The quality of SIP’s manufacturing is very important to the longevity and performance of the product. The panels must be properly bonded, pressed and cured to ensure that they do not delaminate. The panels must also have smooth surfaces and square edges to prevent gaps when joining at the construction site. Before purchasing an integrated panel, check with the manufacturer about their quality control and testing procedures, and carefully read and compare warranty terms.SIPs are available in different insulation materials, usually polystyrene or polyisocyanurate foam.
The integrals are manufactured in a factory and shipped to the job site. The builder then joins them together to construct the house. For experienced builders, SIPs homes can be built much faster than other homes, saving time and money without compromising quality. These savings can help offset the typically higher costs.
Many SIP manufacturers also offer “panel home kits.” Builders simply assemble the pre-cut pieces, and additional openings for windows and doors can be cut on the jobsite with standard tools.
When installed according to the manufacturer’s recommendations, SIP meets all building codes and passes American Society for Testing and Materials (ASTM) safety standards.
Areas of concern
Fire safety is a concern, but by covering the interior of the SIP with a fire-resistant material, such as gypsum board, the facing and foam can be protected long enough to give the building’s occupants a chance to escape.
As with any house, insects and rodents can be a problem. In a few cases, insects and rodents have been known to burrow throughout SIPs, and some manufacturers have issued guidelines for preventing these problems, which include
Applying insecticides to panels
Treating floors with insecticide before and after initial construction and backfilling
Keeping indoor humidity below 50 per cent
Keeping outdoor plantings at least two feet (0.6 metres) away from walls
Trim any overhanging branches.
Boric acid-treated insulation boards can also be used. These panels are insect-resistant but relatively harmless to people and pets.
Because SIP structures are so airtight, well-built SIP structures may require controlled fresh air ventilation for safety, health and performance, as well as compliance with many building codes. A well-designed, installed, and properly operated mechanical ventilation system also helps prevent indoor moisture problems, which is important for realizing the energy-saving benefits of SIP structures.