Why Blown is the Best Insulation Type for Your Existing Walls

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!