Wall insulation · Brisbane & SE Queensland
Wall insulation, Brisbane, pumped & wet-sprayed cellulose.
We pump or wet-spray cellulose into wall cavities so it fills the whole cavity with no gaps, cutting draughts and airborne noise. Western walls, fibro and brick veneer, and honest advice on when it’s not the right call.
I’m Peter Johnson. After 40 years and 6,000 roofs, the same product that goes in your ceiling goes in your walls, but a wall is a different job, so here’s exactly how we do it and where it helps most.
Fills the whole cavity
no gaps, around the studs and wiring
What is cellulose wall insulation?
Pumped into the cavity, not cut into bays.
Cellulose wall insulation is recycled-paper fibre, borate-treated, pumped or wet-sprayed into a wall cavity so it fills the whole space around the studs, noggins and wiring with no gaps. It cuts the draughts and the airborne noise that pass straight through an empty or batt-filled wall. We do it right across Brisbane and South East Queensland.
A wall does the same job as a ceiling, just on the vertical. It’s a barrier between the inside of your home and the weather (or the room next door). The trouble with a batt in a wall is the same as in a ceiling: it has to be cut to fit every bay, and it leaves gaps around the studs, the pipes and the power points. Dense-packed cellulose doesn’t. It flows into every corner of the cavity and sits hard against the frame, so the wall is actually full. Here’s the full case for cellulose.
Because it resists air movement, a packed wall cavity also cuts the draughts that whistle in around power points and wall fittings, and air leakage is a documented 15–25% of a home’s heat loss (yourhome.gov.au). The same Australian Government guide notes that wall insulation itself typically saves around 15% on heating and cooling (yourhome.gov.au) once the ceiling is sorted.
Cellulose pumped into a wall cavity during construction, full contact against the frame, no gaps for heat or noise to slip through.
Two ways into a wall
Wet-sprayed during the build, or pumped in afterwards.
When you do the wall changes the method. If the frame is open we wet-spray; if the wall is already lined we pump it in. Either way the cavity ends up full.
During construction
Wet-spray into the open cavity
If you’re building or renovating and the frame is up but the plaster isn’t on yet, that’s the perfect moment. We wet-spray cellulose straight into the open wall cavity so it bonds in place and fills it completely, around every stud, noggin, pipe and wire. There’s no drilling and no patching afterwards, so it’s the cleanest way to insulate a wall. If your walls are open, call us in before the plasterer arrives.
Retrofit: wall already lined
Pump-in to an existing wall
On a finished home we pump the cavity full through small access points. On a brick-and-tile house it’s non-destructive. We lift a tile above the wall’s top plate and about every third tile around the edge, poke a special pipe down into the cavity between the brick and the timber frame, and pump the wall full from up top. On weatherboard, fibro or hardiboard there’s no tile to lift, so the only way in is from inside (see below).
Fibro, weatherboard & hardiboard: the honest bit about the holes
On a weatherboard, fibro or hardiboard wall there’s no tile to lift, so the only way to insulate it is to drill from inside and pump it in from there. We drill a row of 2 or 3 holes down the wall, every 450mm across it, so a 5-metre wall might be 10 rows of 2 or 3 holes, about 20 to 30 holes in the plaster, cut around 80mm round with a hole saw. A competent plasterer fixes them easily, but the patch-and-paint repair cost is yours, not ours. I’d rather tell you that up front than surprise you on the day.
The hot western wall
Is the heat really coming from the wall?
Before you spend money insulating a wall, work out where the heat is actually coming in. About 3–4pm on a hot afternoon, put your hand on the inside plaster of your western wall, then on an internal wall at the same height. If the western wall is much warmer, the wall is worth pumping.
Then check the ceiling the same way. If the ceiling is cooler than the western wall, the heat’s coming through the wall. If the ceiling is the same temperature or warmer, most of your heat is coming from the roof, not the wall. Sort the ceiling first.
The ceiling is the single biggest heat path in a typical home. The Australian Government’s figures put it at around 25–35%, more than the walls or the floor. That’s a basic guideline, and of course your home’s orientation and wall colour can make a big difference, but it’s why, cost-wise, you get much more bang for your buck making sure the ceiling is done right first, before you go to the expense of insulating the walls.
Source for the heat-flow split: Australian Government, yourhome.gov.au (Insulation).
The one time I don’t pump cellulose
A brick western wall is the exception.
You know by now that cellulose is the product I stand behind. So here’s the one case where I’ll reach for the other one instead, and the fact that I’ll tell you is exactly why you can trust me on everything else.
“Even though I hate fibreglass products, there’s a small chance the cellulose could wick water through a brick external wall, but the pump-in fibreglass won’t. So on a brick external western wall, the fibreglass is the safer pick.”
On every internal wall, every soundproofing job, and most cavity work, cellulose is what I’ll recommend. It fills the cavity completely and adds the mass that knocks noise back. But on a brick external western wall exposed to driving rain, the pump-in fibreglass (a carbon-plus glass-fibre product) is the one that won’t wick moisture through the brick, so that’s the one I’ll quote you. I’d rather lose the cellulose sale than put the wrong product in your wall.
Quieter walls, too
A packed wall is a quieter wall.
A wall cavity packed solid with dense cellulose adds mass and fills the gaps that airborne noise leaks through, so voices, TV and traffic are knocked back. It’s the same reason cellulose makes a strong soundproofing material between rooms and between floors.
I won’t quote you a specific decibel figure without a sound report (acoustic results depend on your whole wall build-up, and sound is a subjective thing) but the direction is clear. Dense-packed, full-cavity, no gaps: that’s what does the work.
Honest answers
Wall insulation: the questions I get asked most.
My western wall gets very hot. Can I insulate it?+
Maybe, but check where the heat is actually coming from first. About 3–4pm, put your hand on the inside plaster of the western wall and on an internal wall at the same height. If the western wall is much warmer, the wall is the problem and pumping it will help. Then put your hand on the ceiling: if the ceiling is cooler than the western wall, the heat is coming through the wall; if it's the same or warmer, most of the heat is coming from the ceiling. The ceiling is the single biggest heat path in a typical home (the Australian Government puts it at around 25–35%, more than the walls) so it's a basic guideline that you get far more bang for your buck checking the ceiling is done right before you spend money on the walls.
How do you pump insulation into an existing wall?+
On a normal brick-and-tile home it's a non-destructive process: we lift a tile above the wall's top plate and about every third tile around the edge, poke a special pipe down into the cavity between the brick and the timber frame, and pump the wall full. On weatherboard, fibro or hardiboard walls there's no tile to lift, so the only way is to drill from inside: a row of 2–3 holes down the wall every 450mm across it. A 5m wall might mean 20–30 holes, cut about 80mm round with a hole saw. A competent plasterer fixes them easily, but the repair and paint cost is yours, not ours.
Do you wet-spray cellulose during construction?+
Yes. When the frame is up and the wall cavities are still open, before the plaster goes on, we can wet-spray cellulose straight into the open cavity so it bonds in place and fills it completely around the studs, noggins, pipes and wiring. It's the cleanest way to insulate a wall because there's no drilling and no patching afterwards. If you're building or renovating and the walls are open, that's the moment to call us in.
Is cellulose or fibreglass better for a wall?+
For most internal walls and the soundproofing job, pumped-in cellulose wins because it fills the cavity completely with no gaps and adds mass. But I'll be straight with you about the one case where I reach for fibreglass instead: pumping a brick external western wall. There's a small chance cellulose could wick water through a brick external wall, and the pump-in fibreglass won't, so even though I don't love fibreglass, on a brick western wall it's the safer pick. That honesty is exactly why you can trust me on the rest.
Will insulating my walls make the house quieter?+
It helps with airborne noise. A wall cavity packed solid with dense cellulose adds mass and fills the gaps that sound leaks through, so voices, TV and traffic are knocked back. I won't quote you a decibel figure without a sound report, because the result depends on your whole wall build-up, but the direction is clear, and it's the same reason cellulose makes a strong soundproofing material between rooms and floors. See our soundproofing page for the full story.
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Got a hot wall or a noisy one? Let’s sort it.
Whether you’re building and the walls are open, or you’ve got an existing western wall cooking the house, fill in the simple online form and I’ll give you an honest quote and an honest answer, including when a wall isn’t worth doing. Servicing Brisbane & SE QLD.
Peter Johnson
Owner / installer · Comfort Zone Insulation Team® · Since 1986
In the trade and want to install it yourself? We make cellulose in Tiaro and run exclusive territories, franchise with the family.