FAQ · Building or renovating
Can you insulate during construction, before the roof or plaster is on?
Yes. Open walls before the plaster goes on are the perfect time to wet-spray cellulose straight into the cavity. No drilling, no patching. The ceiling we pump once the roof’s on and the sparky’s finished. It’s all about the order.
I’m Peter Johnson, and after 40 years and 6,000 roofs the one thing I’d tell anyone building or renovating is this: timing the insulation right is nearly free, and getting it wrong costs you drilling, patching and paint later. So here’s exactly when each part goes in, and how to slot it into your build.
Walls: the moment that matters
Open walls, before the plaster: wet-spray straight in.
The walls are the part where timing really pays off. While the frame is up and the wall cavities are still open. After the electrical and plumbing rough-in, but before the plasterboard goes on. That’s the perfect window. We wet-spray cellulose straight into the open cavity so it bonds in place and fills it completely around every stud, noggin, pipe and wire, with no gaps left behind.
The big win is what you avoid. Doing the walls at the open-frame stage means there’s no drilling holes in finished plaster and no patch-and-paint repair afterwards. It’s the cleanest way there is to insulate a wall. Leave it until the wall’s lined and the only way in is drilling a row of holes from inside, and the repair cost is then yours. So if your walls are open, call us in before the plasterer arrives.
Ceiling: get the order right
Roof on first, electrician finished, then we pump the ceiling.
The ceiling is a different story from the walls. Here you want the roof on and watertight before we touch it, so the ceiling cavity stays dry. The Australian Government’s yourhome guide notes most insulation performs poorly and has a shorter service life if it gets wet, so dried-in first is the rule.
Then you want the electrician finished: cabling run, downlights and exhaust fans fitted. That way we know exactly where the hot fittings are and can keep the proper clearance around every one of them when we pump. Insulation packed hard against a hot downlight is a genuine fire risk, so that order isn’t fussiness. It’s safety. Our trained, qualified installers photograph those clearances, and the photos are checked before you’re invoiced, so you can see it was done right.
Once the roof’s on and the wiring’s done, a new ceiling is the easiest pump there is. It’s open and clear, no old batts to work around, and we lay the cellulose as one seamless blanket across the whole ceiling.
Slotting it into the build
It’s a bit of planning with your builder, not a big job.
None of this is complicated. It’s just sequencing, and a builder who’s done a few houses will know exactly what we mean. Get us in for a look early, before the plasterer’s booked, and we’ll map the insulation to your build program: the walls get wet-sprayed in the slot after the electrical and plumbing rough-in and before the plasterboard, and we come back for the ceiling once the roof’s on and the sparky’s finished.
If you’re owner-building or renovating and the walls are already open, that’s your cue to call. Don’t let the plasterer line them up first, because once they’re closed the only way in is drilling from inside. We’re happy to talk straight to your builder about the order; we’ve slotted into plenty of builds, and it’s a simple bit of planning that saves you the drilling and patching down the track.
During the build
Walls: open-frame stage
- After electrical & plumbing rough-in
- Before the plasterboard goes on
- Wet-sprayed straight into the open cavity
- No drilling, no patch-and-paint later
Once the roof’s on
Ceiling: pumped after lock-up
- Roof on and watertight first
- Electrician finished. Downlights fitted
- Proper clearance kept around hot fittings
- Pumped as one seamless blanket, no batts to work around
More on insulating a new build
Can you insulate during construction, before the roof or plaster is on?+
Yes, and the timing is one of the few things in building you actually want to get right early. Walls are the big one: while the frame is up and the wall cavities are still open, before the plasterboard goes on, we can wet-spray cellulose straight into the open cavity so it fills it completely around the studs, noggins, pipes and wiring. There's no drilling and no patching afterwards, which is why it's the cleanest way there is to insulate a wall. Ceilings are different: there you want the roof on and dried in first, then the ceiling pumped once the sparky's run his wiring and the downlights are sorted. The trick is just coordinating the order with your builder so the walls get sprayed at the open-frame stage and the ceiling gets pumped after the roof's on. Get us in early and we'll tell you exactly when to slot each part in.
When in the build do you wet-spray the walls?+
At the open-frame stage, frame up, roof on so the timber stays dry, electrical and plumbing roughed in, but before the plasterboard is fixed. That's the window. Once those wall cavities are open we wet-spray cellulose straight in so it bonds in place and fills the cavity completely around every stud, noggin, pipe and wire, with no gaps. Because we do it before the plaster, there's no drilling holes in finished walls and no patch-and-paint repair afterwards; the cost and mess of that is exactly what you avoid by getting the timing right. The catch is it's a narrow window in the build program, so the move is to talk to us early and have your builder leave us a slot between the rough-in and the plasterer. Miss it and the walls have to be done as a retrofit later, which means drilling.
Should the ceiling go in before or after the roof and the electrician?+
After both. You want the roof on and watertight first so the ceiling cavity stays dry. Most insulation performs poorly and has a shorter service life if it gets wet, which the Australian Government's yourhome guide spells out. Then you want the electrician to finish: cabling run, downlights and exhaust fans fitted, so we know exactly where the hot fittings are and can keep the proper clearance around them when we pump. Insulation packed against a hot downlight is a genuine fire risk, so that order matters. Once the roof's on and the wiring's done, a new ceiling is an easy pump. It's open and clear, no old batts to work around, and we lay the cellulose as one seamless blanket across the whole ceiling.
How do I coordinate the insulation with my builder?+
Get us in for a look early, before the plasterer's booked, and we'll map it to your build program. For the walls, your builder leaves us a slot after the electrical and plumbing rough-in but before the plasterboard goes up; that's when we wet-spray. For the ceiling, we come back after the roof's on and the sparky's finished. If you're owner-building or renovating and the walls are already open, that's the moment to call: don't let the plasterer close them up first, because once they're lined the only way in is drilling from inside. We're happy to talk straight to your builder about the sequence; we've slotted into plenty of builds and it's a simple bit of planning that saves you the drilling and patching down the track.
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Or call Peter on 0414 586 315 , happy to talk through the timing with you or your builder, no pressure.