Insulation is pumped down the wall cavity from inside the roof space, filling the width of the timber frame behind the brick skin. Where windows break the cavity, bricks are removed externally so the section under the sill can be filled, then carefully re-mortared back into position. Nothing is removed from inside the house, and the whole job is done from the roof cavity and the outside wall.
Why Brick Veneer Needs This Treatment in Older NSW Homes
Brick veneer is one of the most common wall constructions across NSW, and thermally it is the least helpful arrangement. The brick skin sits on the outside, so it absorbs heat all afternoon and keeps radiating it into the evening in summer. In winter, the same bricks stay cold and draw warmth out of the house. The thermal mass is on the wrong side of the wall.
Older homes make this worse because many were built with nothing in the frame cavity at all. A large share of NSW housing built before 2000 has an uninsulated wall frame, which is why the difference after filling it is usually obvious rather than marginal.
The method itself is straightforward but methodical. An installer works from the roof cavity, identifies the top plate of each external wall, and pumps Insulbloc down the cavity until the frame is filled. Because insulation cannot travel past a window opening, those sections are handled separately: bricks are lifted below the sill, the void is filled, and the bricks go back with fresh mortar. This is the step that gets skipped by anyone who tells you brick veneer cannot be fully insulated.
Older homes throw up their own variables. Cavity width varies with the era of construction; some homes have sarking or debris in the cavity, and electrical wiring runs through the frame. Insulbloc is a dry cubed polystyrene product rather than a wet-applied foam, so it does not wet exposed wiring or fittings, and it is hydrophobic, meaning it will not wick moisture across the cavity. It also carries a spread of flame rating of zero and is resistant to fungi, bacteria and vermin.
The performance figure is the reason the work is worth doing. Insulbloc reaches up to TR 6.1 depending on the building material and construction, against roughly TR 2.0 for standard wall batts, and the wall insulation page notes that an uninsulated home can be losing up to 25 per cent of its heating and cooling capacity through the walls alone.
Have an Older Brick Veneer Home?
Whether the cavity can be pumped depends on how your particular walls were built, which is a five-minute check on site. You can read more about brick veneer and retrofit wall insulation at 4 Seasons Home Insulation, or get in touch to book a free measure and quote.
