Choosing the Right Insulation Material for Your Home

Before we dive into the specific materials and applications, it’s important to get an understanding of what insulation does. Insulation materials are made to reduce the rate of heat transfer (how fast heat and the lack there of moves) between your home and the outside environment, keeping your home warm in winter and cool in the summer. 

Insulating with good and high performing insulation materials is essential for your personal comfort. But it also is important to minimise environmental impacts, by reducing the energy needed to heat and cool your home, reducing your energy bill as well!

Insulation does more than temperature control though, it also helps sound proof your home and can be crucial for fire proofing. Sound proofing may be one of your biggest concerns with multi story homes or shared housing, where no one wants to hear the water pump while they sleep or the kids watching TV upstairs!

Taking into account temperature, energy efficiency, soundproofing and fire resistance we can make a good decision on what insulation materials you need. Lets have a look at some home insulation products on the market.

Bulk Insulation Materials 

How does bulk insulation work? Bulk insulation works by trapping air inside the structure, slowing down how fast heat moves through (slowing down heat transfer!)

We use bulk insulation in applications where we need to prevent heat loss during winter (so we stay warm) and keep heat out during the summer (so we don’t cook!)

You’ll find bulk insulation is often made of materials such as fibreglass (or glass-wool), cellulose, polystyrene, polyester, mineral wool and PIR board. Each one of these materials has its unique benefits and all are good thermal insulators.

These materials will come in different forms for different applications, such as polystyrene sheets or boards, polyester blankets, fibreglass batts and more.

Some brand examples you might be familiar with would be Expol polystyrene boards underfloor, Mammoth blankets in the ceiling and PinkBatts fibreglass batts in the walls.

We use these materials to insulate our big three surfaces of your home: Ceiling, Walls and Underfloor.

Lets have a look over each material type before delving into where they are applied, and finally what specific products you have to choose from.

Fiberglass Insulation

Fiberglass is one of the most common types of insulation. Made from fine strands of glass, its excellent as a thermal insulator. Many brands use recycled glass to produce their products making it an environmentally friendly insulation material. You’ll see it come in batts, rolls and less commonly loose fill. It is one of the most versatile materials for home insulation! 

Fiberglass is particularly effective in wall cavities and in your roof or ceiling attic. However we recommend talking to us first before using it in your underfloor crawl space.

Fiberglass is also one of the most affordable choices when it comes to how much does it cost. This makes it very popular both in new builds and existing homes. It's one of the more affordable best insulation for exterior walls.

One benefit of fibreglass is its resistance to moisture, helping to prevent mild growth and damp.

Our caution would be on install to take a lot of care as this material can cause skin irritation that lasts for days, as well as possible dangers to your health if inhaled, swallowed or if it comes in contact with your eyes. Our crews always wear the appropriate PPE (personal protective equipment) when handling fibreglass insulation to ensure everyone is protected and comfortable. Give us a call and we can handle the itchy stuff for you! 

Polystyrene Insulation

Polystyrene board insulation is a common insulation material used in under floor insulation, under slab insulation (insulating below concrete foundation) behind retaining walls and other less common applications.

Polystyrene insulation sheets are long lasting and can help give control over precise placement of where the insulation is needed. 

Though an affordable insulation material, because these sheets and boards can not compress they can bring up freight costs. If you’re very far from a depo or in a hard to reach location, this may be a factor to keep in mind.

The downside is if not installed by professionals, it can leave a mess of polystyrene beads. It also needs to be cut with precision to properly fill the area without any gaps around it. Our team at Island Insulation is very experienced with this product, meaning less waste and environmental impact as well as more effective installs.

Polyester Insulation

Polyester insulation is a long lasting material that is less hazardous to work with than fibreglass and often made of recycled polyester fabrics. 

It often comes in rolls or segments, and can be used as a roof insulation material, wall insulation and in underfloor insulation applications. Like fibreglass and mineral wool it is very versatile!

Mineral Wool

Also known as rock wool or slag wool, mineral wool is made from natural minerals and recycled materials. It's fire-resistant, sound-proof, and provides excellent thermal insulation. 

It's typically used in batts and is suitable for walls, floors, and ceilings. The high density of mineral wool enhances its soundproofing abilities, making it a popular choice in multi-family housing.

Mineral wool's fire resistance is another key advantage, offering peace of mind and additional safety in areas where fire risk is a concern. Additionally, its resistance to moisture and mold makes it a durable option for homes in humid climates. These features make mineral wool a versatile and reliable choice for comprehensive home insulation.

Reflective Insulation

Reflective foil insulation has limited applications. There has been some controversy as it was used widely as an underfloor insulation, but unlike bulk insulation it does not slow heat movement but reflects radiant heat. 

It has since been outlawed as an underfloor option, due to electrical hazards and lack of long term performance.

Read more about reflective foil underfloor insulation in our other articles.

Choosing the Best House Insulation for Different Parts of Your Home

Ceiling / Roof Insulation

The roof and ceiling is a critical area for insulation, as it can be a significant source of heat loss in winter, and a source of high heat in summer when your roofing materials bake in the sun.

Depending on your ceiling and roof design, you may look at skillion roof insulation, “Cold Roof Method” or “Warm Roof Method”. Most common in older homes in New Zealand is the Cold Roof Method, where insulation is laid across the “floor” of the attic space to keep the living space below conditioned and leaving the attic to breath naturally.

For more information on the science and different insulation methods and theories, check out our other articles!

Common options for ceiling insulation materials include

• Fiberglass Batt Insulation

• Polyester Blanket Insulation

• Mineral Wool Batt Insulation 

Ceiling insulation is essential for any home’s comfort! It should be the first thing assessed when looking at your homes insulation. Both in winter and in summer, the most heat transfer will be through your ceiling cavity.

Wall Insulation

Your wall insulation is often your next most important area to insulate (perhaps besides some modern designs with very extensive glassed area, look at our window and door insulation article for more information).

The most efficient insulation for walls is a well planned and installed insulation. Take into account the direction of the sun in summer and in winter, which walls will heat up most and which will stay cold all winter? A few extra dollars spent can be the difference between a comfortable modern home and an uncomfortable summer or winter.  

Common insulation materials are:

• Fiberglass Batt Insulation

• Mineral Wool Batt Insulation

• Blown Insulation (for retro fit wall insulation)

• Foam PIR Board Insulation 

A lot of the decision will depend on the wall cavity thickness, if the wall is too thin for an appropriate fiberglass batt, foam PIR boards provide high insulation value at a far reduced thickness.

Underfloor Insulation

Underfloor insulation is often the easiest upgrade to an existing home. It can be installed without disturbing the occupants and the insulation cost per m2 can be low.

Underfloor insulation can help stop cold air seeping up from the crawl space. A proper crawl space renovation may seem excessive but with underfloor insulation, moisture barriers, and good ventilation you can significantly improve the air quality in your home.

Underfloor insulation also helps reduce noise from water pumps, hot water cylinders and other appliances under the house.

Common insulation materials for underfloor applications:

• Polystyrene Board Insulation

• Polyester Blanket Insulation

At Island Insulation we caution away from using batts underfloor unless you plan to line under the floor joists. This will allow us to create a easy to service crawl space without itchy fibreglass particles which looks clean and neat!

Insulation Options in New Zealand

New Zealand unique climate requires different solutions and insulation materials depending on your climate zone. Our article on climate zones and what that means for your build is coming soon!

We also have unique insulation brands that are highly reputable and good to work with. In our next articles we will go into depth on insulation brands and what they have on offer.

Factors to Consider When Choosing Insulation

The big factors to consider when choosing from these materials include:

• R Value (How good that product is at insulating)

• Environmental Impacts

• Cost of the Insulation Material

• Installation Costs and Difficulty 

• Fire Resistance

In our coming article on R values and how they work we will discuss how to read R value in depth. The prices of insulation are on our site, or feel free to reach out for a free consult on your next projects insulation needs.

Conclusion 

Selecting the right insulation material is a vital step in ensuring your home is energy-efficient, comfortable, and environmentally friendly. 

By understanding the different types of insulation and considering factors like R-value, environmental impact, and cost, you can make an informed decision that will benefit your home in the long run. 

Whether you are building a new home or upgrading an existing one, the right insulation can make a significant difference in your comfort and energy bills.

Get in touch with our team today to start planning your next project!