What Is The Best Insulation For Outside?

Regardless of where you live, most cities in the world have to contend with varying and sometimes extreme weather conditions, with Melbourne being no exception! With a reputation for hosting four different seasons in one day, regardless of what time of the year it is, our city is known for having some crazy cold days in summer, and even some pleasant ones in winter—not to mention that our summers are extending well into the winter calendar, and vice versa.

When weather conditions become increasingly volatile and swing from one extreme to another, what is the best way to keep up comfortable temperatures in your home and even your workplace? While using air conditioners and heaters guarantees a rapid readjustment of your internal climate, it comes at a cost. Artificial air is not as healthy for you as natural air, and electricity bills can quickly stack up when these devices are run all day.

The best and most organic solution for creating a balanced climate at home is, in fact, insulation. When you fit your home or office with insulation, you are ensuring the best protection against unpredictable weather conditions, along with a whole host of other advantages for you and your home. But, of course, this leaves the question: What is the best insulation for you? To help with this, today, we have put together a short guide that will give you more clarity on the right insulation solution for you.

Why Insulation? Benefits

When it comes to choosing insulation, there are many great reasons. The most obvious benefit of having a well-insulated property is increased thermal efficiency. In essence, thermal efficiency measures your home's ability to maintain a desirable temperature internally. To make any space more efficient at this job, insulation must be fitted. With good high-quality insulation, you have the best chance of maintaining the kind of climate you want in your home, regardless of what time of the year it is.

Naturally, once you insulate your home, you will exponentially minimise the need to run your air conditioners and heaters as much as you previously did. As one would expect, this will help you to keep more money in your pocket and less going towards your gas and electricity bills. Once you make your initial outlay for insulation, it is predominantly recouped via these significant savings.

Another incredible benefit derived from reducing how much you run your appliances is the contribution to the environment that naturally occurs. By really limiting your use of these appliances, you cease to take excessive amounts of natural resources from the earth, in turn reducing your carbon footprint and helping to create a better planet.

If you decide to insulate while building a home, you will also find that the construction phase benefits from a speedier build. This is because, as insulation covers the interior of a building under construction, internal works can proceed uninterrupted, regardless of whether or not bricking or classwork has been completed.

One more fantastic advantage of insulation is that it provides your building with some level of sound dampening. This means quieter inside, as this extra layer of insulation material further prevents sound from your home from being heard outside and external sounds from being heard inside your home.

To offer some more specific perspective on what insulation can do for you, over 50% of a household energy budget can be spent on heating and cooling a home in Victoria. As discussed previously, this can be cut down significantly with insulation. Homes that do not have insulation stand to lose up to 35% of their heat through the roof in winter and gain around the same amount of heat during summer. Through the windows, heat loss is around 10-20% in winter and heat gain can reach 35% in summer. The walls of a home gain and lose heat at up to 25%, while heat loss through the floor can be as high as 20%.

Understanding R Values

Before we dive into the different types of insulation to choose from, it's important to understand R values. Essentially, R-value is a way of measuring your insulation's ability to resist heat flow. You will notice that R values range from 1.5 to 7, and the higher the R-value of insulation, the more effective it is at insulating your property. When discussing R values, there are three that you need to know about:

  • 'Up' R-Value
    • This measures the insulation's resistance to heat flow out of a building. Another name for this is the winter R-value, as it is desirable to have a high up R-value in winter to keep precious heat in your home.
  • 'Down' R-Value
    • This measures the insulation's resistance to heat flow into a building. Another name for this is the summer R-value, as it is desirable to have a high down R-value in summer to keep your home cool by leaving the heat out.
  • Total R-Value
    • The total R-value is the up and down R-value combined. Whenever you hear the term R-value, it is usually referring to this.

When selecting the appropriate R-value for your home, selecting the highest won't always benefit you. This is because different build styles of homes, and different environments, call for different levels of heat resistance. For example, one home may require insulation rated with an R-value of 7, while another can have the same level of protection at an R-value of 4. To find out what's right for you, it's best to have somebody assess your home.

Different Types of Insulation

There are a few key types of insulation that are commonly utilised in Australia today. These are reflective insulation, bulk insulation and (to a lesser degree) spray foam insulation.

Reflective Insulation

Reflective insulation is extremely effective and cost-efficient insulation commonly used in homes across Australia today. Reflective insulation is essentially created out of an aluminium-foil-like material, and it works by deflecting radiant heat away from home when it tries to enter. Most effective in warmer climates (though also good in cooler ones), reflective insulation can be fitted within walls, in the roof/ceiling area and under the floor. 

Bulk Insulation

The most common form of insulation available to purchase from insulation specialists and hardware stores, bulk insulation works by trapping air inside millions of tiny bubbles as a way to prevent the flow of heat from entering your property. It is available in rolls, boards and batts and produced from various materials. It is mostly made from glass wool, natural wool, polyester, cellulose fibre and recycled paper. In addition, bulk and reflective insulation can be installed to create a hybrid configuration to maximise effectiveness.

Spray Insulation

A relatively recent development in the world of insulation, spray foam insulation is quite effective and serves a great purpose that no other insulation truly can. You apply this insulation by spraying a solution in the floor, walls or ceiling, causing a bubble up into a thick layer of insulation. The R-value is higher than most traditional forms of insulation, and it also resists moisture, which means it won't sag as quickly as bulk insulation. The one thing about spray insulation that may make you reconsider whether to go for it or not is that it costs more than traditional insulation and is also more flammable. A good use for spray insulation is in hard to reach places that are difficult to protect with traditional insulation fully. Spray insulation too can be joined with reflective and batts to form a hybrid.

Insulating your walls

The methods you can use to insulate your walls vary depending on what type of walls you have. Generally, the best type of insulation is known as bulk insulation. Bulk insulation contains millions of tiny pockets filled with air – gases are:

  • Poor conductors of heat.
  • So the more pockets of air you have.
  • The better the insulation.

It's called bulk insulation because it's bulky, and it may come in spray, board, or batts/blanket form. Board and blanket insulation are great for walls you have easy access to, like the walls in your attic, and you can often install this type of insulation yourself.

Other walls, like double brick walls, can't be insulated with conventional methods because it's impossible to access the wall's interior without special tools. For these walls, spray insulation is preferred. First, small holes are made in the walls; the insulation is then sprayed into those holes until the wall's interior is filled with it. The holes are then closed up with mortar.

You need to keep in mind that this method tends to cost a bit more because you need to hire a professional to install the insulation for you. On the plus side, though, you can be advised by that specialist what type of insulation will suit your property best, and you can be sure that the installation will be successful.

what is the best insulation for outside (2)Those living in the hottest regions of Australia should generally avoid bulk insulation and instead opt for reflective insulation (sometimes called radiant barriers). This type of insulation is particularly good at reflecting the sun's rays, preventing them from overheating your home. In addition, since it doesn't trap the heat inside, your home can cool off easier on those hot days.

FAQs About The Best Insulation For Home

Yes, the higher the R-value, the better the insulation. A higher R-value indicates that the insulation product better resists heat transfer.

The best type of insulation for exterior walls acts as a thermal break, acts as a radiant barrier and has an insulated core. This will increase performance by resisting radiant heat, convection and conduction heat transfer.

The R-value is dependent on the material thermal resistance but also thickness. If you double the insulation thickness of the same material, the R-value is doubled.

To add to the confusion of insulation values, both the imperial and metric systems use the same symbol, R. The USA uses imperial units of Fahrenheit, square feet, and BTU. The metric value uses Celsius, square metres and Watts. As a result, websites in America will show R values approximately 5.68 times as large as the same value in metric. E.g. R2 in metric is equal to R11.3 in imperial.

Yes. Any part of the house's envelope that is not insulated will be less resistant to heat transfer. For example, a retrofit installs to a timber floor will greatly improve the house's energy efficiency. Any floors with in-slab heating are required to have insulation, and it is becoming more common to insulate concrete slabs by putting insulation into the slab.

It is not so much the important thickness but the thermal resistance. This is because different materials have different R values at the same thickness.

Building regulations and energy design need to be considered, but again thickness is not as important as R-value.

Australia's Best Roof Insulation

In this guide to the best roof insulation in Australia, you'll find out what type of insulation you need, what R-Value is ideal and where to buy high quality, affordable insulation online.

Bulk Vs Reflective Insulation: Which One Do You Need?

There are two main categories of roof insulation; bulk and reflective insulation. Bulk insulation has millions of tiny air pockets and works by trapping air within its structure. Bulk insulation cannot be compressed, reducing its air pockets and compromising its insulating ability. This insulation works by reducing the conduction of heat flow between objects adjacent to each other.

On the other hand, reflective insulation primarily affects radiation heat flow. It usually consists of a foil layer backed by a paper or plastic layer. The reflective foil needs to be kept clean to work properly, and the reflective side must be faced downwards. More recently, roof insulation has been designed to incorporate bulk and reflective insulation for the highest performance and insulating capabilities.

What Is The Best Insulation Material For Roofs?

Roof insulation is made from several different materials, whether it is bulk or reflective insulation. The most common bulk insulation materials used are glass wool and polyester. At Pricewise Insulation, we have a variety of glass wool and polyester roof insulation products to suit many home styles and desired thermal performance.

Glasswool Bulk Insulation

Glasswool insulation is made from recycled glass materials and is the most common insulation material used in residential and commercial buildings. Although glass wool has a stigma of being itchy and uncomfortable to install, recent technological advances have improved this. Today, many glass wool insulation products claim to be low-itch or itch-free.

Polyester Bulk Insulation

Polyester insulation is manufactured from recycled PET plastics such as drink bottles. Polyester insulation is bonded together by heat, and no binder chemicals are added. This gives polyester its rigid, flexible and hypoallergenic structure.

Foil Reflective Insulation

Foil insulation has a reflective surface that creates a radiant barrier against heat transfer from the sun. Foil insulation must be installed correctly to ensure its full insulating capabilities are reached. The R-Value of reflective foil insulation will depend on installation and your living climate.

Should I Buy Roof Insulation Batts Or Rolls?

what is the best insulation for outside (2)This depends entirely on your personal preference as functionally. Both these forms of bulk insulation are equally effective at insulating. The main difference is how they are installed. Roll insulation can be 'rolled' out between the ceiling joists without cutting into segments. This is especially useful for ceiling spaces with few obstacles and a large space to work in (which are generally few and far between!).

However, insulation batts may be a more appropriate option if you have many obstacles and a small ceiling space area. As batts are pre-cut, they are easy to install and cut to fit any space.

Are You Retrofitting Ceiling Insulation Or Installing During A New Build?

Insulation installers can install ceiling insulation in both new and existing homes. In some cases, installing new insulation over old insulation may be possible to boost the overall R-Value. However, if the old insulation is damaged, mouldy or infested, it should be completely removed before the new insulation is installed.

Pitched Roof With A Flat Ceiling

For pitched roofs with a flat ceiling with crawl space, it may be possible to install insulation from inside the ceiling space. We recommend installing insulation batts in between the ceiling joists and installing sarking or foil batts beneath the roof to help with radiant heat.

Roofs With No Crawl Space

For roofs with no crawl space, for example, if you lift a metal roof to install insulation, we recommend putting down insulation batts first on top of the plaster. Then we suggest putting down some sarking or Kingspan Air-Cell Insulation with the silver side up to reflect radiant heat away from the house.

For tailored advice about the best roof insulation for your project, give our insulation specialists a call, and we'd be happy to talk you through your options.

What Is A Good R-value For Roof Insulation?

To answer the question "What is the most effective roof insulation?" the most important factor you should consider is the R-Value of the insulation product. The R-Value indicates how effective it prevents heat loss and heat gain. The higher the R-Value, the more effective the insulation product is, and the more potential savings you can make on your energy bills.

The roof is responsible for the greatest heat loss and heat gain in a home – as much as 35%! So choosing the right R-Value for roof insulation is very important to ensure your home can regulate temperatures well all year round. There are guidelines in the Building Code of Australia outlining the minimum R-Values installed based on where you live.

What Is The Best R Rating For Ceiling Insulation?

For cooler climates such as Melbourne, Sydney and Adelaide, we recommend at least R5.0 or R6.0 for the ceiling. For warmer climates such as Perth and Brisbane, we recommend at least R4.0.

What Type Of Insulation Is The Most Energy-Efficient?

A high R-Value means better insulating power and greater energy efficiency. If your budget allows, we recommend upgrading to the highest R-Value you can afford, as this will lead to greater temperature control and higher energy efficiency in your home.


All in all, when selecting the perfect insulation for you, it comes down to various factors, including your home type, climate and budget. However, with all the information you've learnt today, you should be able to make a much more informed decision regarding insulation.

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