How to Choose The Right Type of Insulation For Your Building

Effective insulation plays a crucial role in keeping your home warm, saving you substantial amounts on energy expenses and reducing CO2 emissions. Given the rising costs of energy, ensuring proper insulation is increasingly important. Estimates suggest that the average home may be losing up to 30% of its heat through the roof and walls if it is not properly insulated.

When it comes to insulating your building, there are a wide array of options available, each with its own advantages and disadvantages. Your choice should be based on specific factors such as the location of insulation, your budget constraints, which type offers superior insulation or easier installation.

We explore a variety of insulation types and discuss which could be best for your building.

Types of Insulation Material

Insulation can be made from a range of different materials, each with its own pros and cons:

Fibreglass - Common and relatively inexpensive. It suits both residential and commercial buildings and can fit into small spaces. Fibreglass is fire-resistant.
Cellulose - Made from recycled paper products. It's environmentally friendly and can be blown into existing walls, making it great for retrofits.
Foam Board or Rigid Foam - These are good for insulating roofs and foundations. They provide high R-values and can be used in small spaces.
Spray Foam - Provides a superior air barrier and is excellent for sealing cracks and gaps. It’s versatile and can be used in various spaces.
Reflective Insulation - This uses reflective surfaces to reflect radiant heat away from living spaces, making it ideal for attics in hot climates.
Natural Fibres (like wool or cotton) - Environmentally friendly and offer good thermal performance.
Mineral Wool (rock and slag) - Offers excellent thermal and acoustic insulation for both commercial and residential properties.

Consider R-Values

The R-value is a measure of thermal resistance used in the construction industry. It quantifies how effective an insulating material is in resisting the flow of heat. A higher R-value indicates better insulating properties. In simple terms, the R-value measures how well insulation can keep heat from flowing through it.

Different materials have different R-values, and the appropriate R-value for insulation depends on factors such as climate, building codes, and specific construction needs. The higher the R-value, the better the insulation’s effectiveness. Choose an appropriate R-value for your climate and space constraints.

Which Type of Insulation Should I Choose?

Type of Insulation	Insulation Material	Where to Use	How to Install	Advantages of Using
Blanket Batts and Rolls	- Fibreglass - Plastic fibres - Natural fibres - Mineral Wool	- Unfinished walls - Floors - Ceilings - Foundation walls	Fit between studs, joists, and beams.	- Relatively cheap - Ideal for standard stud and joist spacing that doesn’t have many obstructions. - Suitable for DIY
Foam board or rigid foam	- Polyurethane - Polystyrene - Polyisocyanurate	- Unfinished walls and foundation walls - Floors - Ceilings - Unvented roofs	Installed in cavities or stud work during construction. For refurbs, applied inside a timber frame internally or by insulated plasterboard attached directly to walls.	- High insulating value for relatively little thickness (R-value). - Stronger and less likely to sag.
Spray Foam Insulation	- Polyurethane	- Enclosed existing wall - Open new wall cavities - Unfinished attic floors	Applied using a spray can. Can be used in both small gaps and in larger spaces.	- Good for existing finished areas, irregularly shaped areas, and around obstructions. - Fills nooks and crannies. - High insulation value.
Loose-fill and blown-in insulation	- Cellulose - Fibreglass - Mineral wool	- Enclosed existing wall or open new wall cavities - Unfinished attic floors - Hard to reach places	Blown into place using special equipment	- Ideal for existing finished areas, oddly shaped areas, and around obstructions. - Cost-effective
Insulating concrete forms (ICFs)	- Foam boards - Foam blocks	- Unfinished walls - Foundation walls for new construction	Installed in the wall as part of the building structure. The cores in the blocks are often filled with concrete.	- Insulation is built into the walls, creating high thermal resistance. - Usually means no other insulation will be needed.

Blanket Batts and Rolls of Insulation

Soft rolls and semi-rigid batts of insulation offer versatile applications, suitable for floors, ceilings, and unfinished walls. Comprising flexible fibres like fibreglass, plastic fibres, mineral wool (rock and slag), and natural materials such as cotton or sheep's wool, this insulation fits snugly between studs, joists, and beams, as long as they are relatively free from obstructions, like pipes.

Pros of Blanket Insulation

DIY-Friendly: Quick and easy to install, especially when using pre-cut batts, making it accessible for do-it-yourself projects.
Affordable: Relatively low-cost compared to other insulation types, making it budget-friendly.
Durable: Maintains its shape over time, as it doesn't shrink, ensuring long-term effectiveness.
Eco-Friendly Options: Natural variants made from non-irritant cotton and sheep's wool are available, providing environmentally conscious choices.

Cons of Blanket Insulation

Sagging Possibility: Rolls or blankets may sag on vertical surfaces, reducing effectiveness; thus, firm fixing to the blockwork skin of a wall is essential.
Bulky: Can be challenging to fit around obstacles or into confined spaces due to its bulkiness.
Protective Measures: Installing rockwool and fibreglass requires protective gear to prevent itching, skin rashes, and issues caused by inhalation.

Foam Board or Rigid Foam Insulation

Foam boards and rigid panels of insulation offer comprehensive coverage for insulating various parts of a building, ranging from foundations to the roof. These boards are typically made from chemical materials such as polyurethane, polystyrene, and polyisocyanurate. During property extensions, foam board insulation is commonly integrated into cavities or stud work. In older properties with solid walls, it can be applied internally within a timber frame or attached directly to the wall using insulated plasterboard during refurbishments.

Pros of Foam Board or Rigid Foam Insulation

Efficient Insulation: Provides excellent insulation (high R-value), often twice as effective as other insulating materials.
Strength and Durability: Sturdy and less prone to sagging compared to soft batt and blanket insulation options.
Effective Sealing: Resistant to water and air leaks, offering superior protection against moisture and drafts.

Cons of Foam Board or Rigid Foam Insulation

Higher Cost: More expensive due to its dense composition, making it a pricier insulation option.
Air Leakage Concerns: Joints between sheets or boards must be properly taped to prevent air leakage, ensuring optimal effectiveness.
Fire Safety: Releases flammable, toxic gases after combustion, necessitating careful consideration of fire safety measures.

Spray Foam Insulation

Spray foam insulation is a versatile solution used to minimise air leakage in unfinished attic floors, new wall cavities, and existing walls. This method is incredibly adaptable and can be injected into the tiniest crevices, including cracks in window and door frames, as well as large and uniquely shaped spaces. Upon application, the foam expands to fill every corner, creating a nearly airtight seal.

There are two main types of foam insulation: breathable (open-cell) and non-breathable (closed-cell), both of which are usually made from polyurethane. Closed-cell foam contains gas that aids in expansion, providing robust resistance against air leakage and moisture. In contrast, open-cell foam, filled with air, has a spongy texture. As such, open-cell foam shouldn’t be used in below-ground applications, like basements, as it may absorb water.

Pros of Spray Foam Insulation

Suitable for Finished Areas: Effective for adding insulation to existing finished spaces.
Versatile Application: Ideal for irregularly shaped areas and around obstacles such as pipes, ensuring comprehensive coverage.
No Settling: Does not settle or sag, filling all spaces where it's installed.
High Insulation Value: Provides excellent insulation per unit thickness.

Cons of Spray Foam Insulation

Higher Cost: Can be more expensive than traditional insulation methods like batt insulation.
Professional Installation: Requires installation by a licensed contractor, increasing overall expenses.
Safety: Some foam materials made from polyurethane contain toxic compounds that raise potential health concerns, so professional installation is required.

Loose-fill and Blown-in Insulation

Crafted from lightweight materials like cellulose, fibreglass, or mineral wool, this insulation can be either loose or blown into place using specialised equipment. It finds applications in enclosed existing walls, new wall cavities, unfinished attic floors, and challenging-to-access areas.

Pros of Loose-fill and Blown-in Insulation

Cost-Effective: Good value for the results achieved.
Versatile Application: Suitable for insulating finished areas, irregular spaces, and around obstacles like pipes.
Sustainability: Natural alternatives like cellulose (old newspapers) and wool are more eco-friendly options.

Cons of Loose-fill and Blown-in Insulation

Higher Cost: Can be pricier compared to other loft insulation options.
Professional Installation Required: Not suitable for DIY installation; professional setup is necessary.
Potential Sagging: Over time, cellulose and wool may sag, leading to a decrease in its U-value (thermal transmittance).
Dust Hazard: Installation requires wearing a protective mask due to dust particles.

Insulating Concrete Forms (ICFs)

Foam boards or foam blocks can be integrated into the building's structure. The cores of these blocks can then be filled with concrete, making them well-suited for foundation walls in new extensions and unfinished areas.

Pros of Insulating Concrete Forms (ICFs)

Built-in Insulation: Insulation is seamlessly integrated into the walls, providing excellent thermal resistance.
Reduced Need for Additional Insulation: Minimises the requirement for supplementary insulation methods.

Cons of Insulating Concrete Forms (ICFs)

Thickness Challenges: Walls can become excessively thick, posing issues in smaller spaces.
Bracing Requirement: A bracing system is necessary to maintain the walls' straight alignment, which can make installation more complex.
Cost: Cost is a significant factor to weigh when opting for this insulation method.

Consider What Your Building Needs

While considering different insulation types, there are a few factors to keep in mind:

Climate - Consider your location. Colder climates may require higher R-values (thermal resistance), which means thicker or more efficient insulation.
Budget - Different types of insulation vary in cost. Determine how much you can afford to spend on insulation.
Moisture - Some insulation materials are better at resisting moisture, which is essential in damp environments.
Space - Consider how much space you have for insulation. In some cases, thinner, high-efficiency materials might be necessary due to space constraints.
Maintenance - Consider the long-term maintenance. Some insulations might degrade over time or lose their effectiveness if not properly maintained.
Safety - Consider fire safety ratings, especially if you're insulating an area where fire safety is a concern, such as a garage.

By considering all of these factors, you can make an informed decision about the right type of insulation for your building.