If your home was built before the 1990s, there’s a very good chance the walls are completely empty. Ceiling and underfloor insulation became common decades earlier, but wall insulation simply wasn’t required — so builders left the cavities bare.
That matters because heat always moves from warm to cold. In winter, the warmth you pay for passes straight through uninsulated wall linings and out into the Waikato fog. Research puts the loss at up to 25% of a home’s total heat — more than escapes through the floor.
How to tell if your walls are empty
A few tell-tale signs: rooms that never feel warm no matter how long the heater runs, walls that are cold to the touch on winter mornings, and condensation or mould appearing on wall surfaces — especially in corners and behind furniture.
The definitive check takes minutes: we drill a small inspection hole in an inconspicuous spot and look inside the cavity. It’s part of every free assessment we do.
Cold wall surfaces don’t just waste heat — they invite condensation, and condensation invites mould. Insulating the walls treats the cause, not the symptom.
What retrofitting actually involves
This is the part that surprises people: for most homes, there’s no relining, no gutting, no weeks of disruption. CosyWall insulation is blown into the existing wall cavity through small holes — usually drilled through the exterior cladding, sealed and repainted the same day.
Where outside access isn’t practical, we can work from the inside through the plasterboard instead. And if you’re already renovating with the linings off, that’s the perfect moment for maximum performance. Most homes are finished in about a day, with an installed R-value of around R2.2 and a 50-year product guarantee.
Is it worth it?
Walls are usually the biggest uninsulated area left in an older home. Fixing them completes the thermal envelope — warmer rooms, lower power bills, drier surfaces, less mould. If you’ve already done the ceiling and floor, the walls are almost certainly your best next upgrade.
Wondering what your home needs?
We’ll check for free, anywhere in Hamilton and the Waikato.
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