If your home was built before the 1990’s and you are having a hard time keeping it warm this winter, you may find it has little or no wall insulation. Even newer homes can have thin or patchy insulation that doesn’t hold in the warmth. If you are looking for the best insulation for existing walls, a blown wall insulation system like CosyWall is one of the most effective options. 

Why blown insulation is ideal for existing homes 

Blown wall insulation is designed for retrofitting into homes without the need for major renovations. Unlike other methods that involve removing wall linings or replacing cladding, CosyWall can be installed quickly and with minimal disruption. This means you can upgrade the comfort and efficiency of your home without weeks of messy building work. 

Most installations can be completed in a single day. Our team drills small, tidy holes in the wall cladding or linings, blow in the insulation to fill the entire cavity, then seal and finish the holes so everything looks neat. The process is clean, fast and designed to keep your home weathertight. 

How CosyWall insulation works 

CosyWall is a high-performance dry fibre insulation. It is installed at a density that completely fills the cavity, leaving no gaps or voids where heat can escape. Once the insulation is in your walls it stays in place and will not slump or settle over time. This ensures it performs for the life of your home, keeping it warm in winter and cooler in summer. 

The system is CodeMark certified, which means it meets strict New Zealand building standards. You can be confident the product is tested, proven and installed using a controlled process that protects the structure of your home. 

The R-values you can expect 

R-values measure how well insulation resists heat flow. The higher the R-value, the better it performs. CosyWall delivers higher R-values than many traditional insulation products because it is blown in at a density that fully packs the wall cavity. By removing gaps and voids, the insulation forms a continuous barrier that helps hold the warmth in and keep the cold out. 

This can make a big difference to your power bills. With proper wall insulation, your home loses less heat, so your heating system doesn’t have to work as hard to keep the temperature comfortable. 

Fast and simple installation 

Most CosyWall installations are completed in one day. Our team will assess your home, explain the process, and recommend whether the insulation should be installed from inside the home or through the exterior cladding. The holes are small and are sealed once the insulation is in place, leaving your home tidy and protected. 

Because there are no major renovations involved, you can usually carry on with your day while the work is being done. Once finished, the difference in comfort is noticeable straight away. 

Take the next step 

If you are ready to find out how much it costs to insulate your walls, try our free wall cost calculator. You can also contact our team to arrange a free assessment. We will help you choose the best insulation for existing walls and create a warmer, more comfortable home for you and your family. 

When winter hits, and the temperature starts to drop you may start looking for ways to warm up your home. For some, the first thought is installing a new heat pump. But before you go down that track, it’s worth thinking about where your home might be losing heat in the first place. 

Adding wall insulation is one of the smartest ways to improve the warmth and comfort of your home. It works quietly in the background and keeps the heat in, right where you want it. 

Why Heat Escapes Without Wall Insulation 

Most homes built before the 1990s were not built with insulation in the external walls. Even homes built after that may have thin or patchy insulation that doesn’t do much to hold the heat in. If your walls are not insulated properly, a large amount of heat escapes straight through them. 

BRANZ research shows that uninsulated walls can account for up to 25 percent of heat loss in a home. That means one quarter of the heat you’re paying for is going straight out the wall. Even the best heat pump won’t solve this problem if the heat can’t stay in the room. 

What Wall Insulation Does 

Wall insulation slows the movement of heat. In winter, it stops heat from escaping through your walls. In summer, it helps block hot air from getting in. This creates a more stable temperature inside, which means you use less heating and cooling overall. 

The CosyWall system uses a dry, blown glasswool insulation that completely fills the wall cavity. It reaches into all the corners and gaps that traditional insulation can miss. Once it’s in, it works for the life of the home and requires no maintenance. 

Why Insulation is a Long-Term Fix 

A heat pump is one of the most energy efficient ways to heat your home, but it still relies on electricity to run. If your home isn’t well insulated, a lot of that heat will escape, meaning your heat pump must work harder and run longer to keep the space warm. That can lead to higher energy use and bigger power bills. 

Wall insulation helps stop that heat from escaping in the first place. It reduces how often you need to use your heat pump and helps it work more effectively. Once installed, insulation works year after year without needing any maintenance. There are no filters to clean, no parts to service, and no switches to turn on or off. It quietly does its job in the background, keeping your home warm and dry. 

Make Your Heating Work Better 

Even if you already have a heat pump, adding wall insulation can help it work more efficiently. When your walls are insulated, the warm air your heat pump creates stays inside longer. That means you won’t have to run the pump for as long or as often. Your home reaches the right temperature quicker and holds that warmth for longer. 

Think of insulation as giving your home a better “thermal shell”. It’s not about replacing your heating system but helping it perform better. 

What’s the Better Investment? Installing a New Heat Pump or Insulating Your Walls 

While both wall insulation and heat pumps are useful, insulation gives you long-term benefits that keep adding up. You pay once, and it keeps saving energy every day. It also adds to the value of your home and makes it more comfortable year-round. 

A new heat pump may still make sense for some homes, especially if you have no existing heating. But if you already have a heat source and your walls aren’t insulated, the better first step is clear. Insulate the walls and keep the heat in. 

Ready to Insulate Your Walls? 

If you’re thinking about making your home warmer and are interested in understanding the cost of installing wall insulation, try out our wall insulation calculator or feel free to give us a call on 0800 267 992. 

Adding insulation to your walls is one of the most effective ways to improve comfort and energy efficiency in your home. If you own an older home, there’s a good chance your walls aren’t insulated. Most homes built before the 1990s were constructed without insulation in the external walls. Even homes built later may have thin or patchy wall insulation that doesn’t meet today’s standards. While ceiling and underfloor insulation have become common upgrades, walls are often left without insulation. This can lead to significant heat loss, especially in winter. 

Why Wall Insulation Matters 

Wall insulation helps regulate the temperature in your home. It keeps heat in during winter and helps keep your home cooler in summer. Without wall insulation, warm air escapes through the walls in cold months, and hot air gets in during warmer months. This makes it harder to maintain a steady indoor temperature. 

Research from BRANZ shows that up to 25 percent of a home’s heat can be lost through uninsulated walls. That means a quarter of the energy you pay for could be disappearing straight through the walls. Heating systems like heat pumps need to run for longer, using more electricity and driving up your power bills. 

Wall insulation can also help reduce noise between rooms and from outside. It can make your home feel drier and more comfortable. 

How Blown Insulation Works 

Blown insulation is made from dry, loose glasswool fibres that are installed into the wall cavity using specialised equipment. The fibres are blown under pressure through small holes drilled into each wall cavity. This method fills the entire space, including tight corners and gaps around wires and pipes. 

At CosyWall, we use a CodeMark certified system designed specifically for New Zealand homes. The insulation doesn’t sag or settle over time. It creates a consistent thermal barrier across the full wall area, giving the home better thermal performance. 

Why Blown is the Best Insulation Type for Existing Walls 

If you live in an older home and your internal wall linings are still in place, blown insulation is often the only effective option. Other types of insulation usually need full wall access, which means removing plasterboard or cladding. That can be messy and expensive. 

The CosyWall system can be installed with minimal disruption. Small holes are drilled into each wall cavity, the insulation is blown in, and the holes are then sealed and painted. The job is tidy and often completed in just one day. 

Blown insulation gives better coverage because it fills every part of the wall cavity. Batt like products can leave gaps and voids, especially around obstacles. These gaps reduce the effectiveness of the insulation. Because CosyWall fills the entire space, it creates a complete thermal barrier that performs more like the walls in a new build. 

Signs Your Walls May Be Uninsulated 

If your home was built before 1990 and hasn’t been renovated, there’s a good chance the walls are uninsulated. Some common signs include: 

• Rooms that feel cold in winter 
• Walls that are cold to touch 
• High power bills 
• Condensation on windows or in the corners of rooms 

The best way to know for sure is to book a wall insulation assessment with us at CosyWall.  

Book a Free CosyWall Assessment 

If you’re unsure whether your walls are insulated, we can help. At CosyWall, we specialise in retrofitting insulation into existing New Zealand homes. Our team will check your walls, explain the process, and recommend the best way to insulate your home. 

Blown insulation is the best insulation type for existing walls because it can be installed without removing linings, gives complete coverage, and performs for the long term. Learn more about how the system works and book an assessment at www.wallinsulation.co.nz. We also have created a wall insulation calculator to provide an estimate on the cost of insulating your walls. Try the calculator out for yourself now!