Pre-Plaster Inspection
An independent check of the rough-in, insulation and fire collars — and the frame behind them — before plasterboard closes the cavities.
Book after rough-in, before plasterboard
Why Pre-Plaster Is the Last Cavity Check
Pre-plaster — also called pre-line — is the stage after the trades have roughed in and before plasterboard goes up. It is the last point at which the inside of every wall and ceiling cavity is open: the rough-in, the insulation, the fire collars and the frame behind them are all visible at once, and only at once.
This stage matters because the trades that just worked in the frame can compromise it. AS 1684.2 Residential timber-framed construction limits how much a stud, brace or bearer can be notched or drilled; the fire-separation provisions of NCC Volume Two Part 3.7 require collars at penetrations through fire-rated walls; and insulation only delivers its rated R-value if it is installed gap-free and uncompressed, per AS 3999.
Once plasterboard is fixed, a notched brace, a compressed batt or a missing fire collar is invisible. The pre-plaster inspection is the only stage that sees the rough-in and the frame together before both are covered.
What's Included
- Electrical rough-in — cable routing, box positions
- Plumbing rough-in — supports and penetration collars
- Fire collars at penetrations through fire-rated walls
- Insulation — R-value, gap-free, uncompressed
- Wall noggings for future fixtures and fittings
- Structural bracing not notched or cut by trades
- Wet-area wall membrane where installed at this stage
- Ceiling framing and noggings for cornice and downlights
- Weather damage to the frame during lock-up
- Same-day PDF report with photos
Includes GST
Critical Elements We Verify
Rough-In
Electrical and plumbing routing
Insulation
R-value, gap-free, uncompressed
Fire Collars
Penetrations in fire-rated walls
Frame
Not notched or cut by trades
What we check at pre-plaster stage
The inspection works through every cavity while it is open, checking the rough-in of each trade, the insulation and the frame behind them. The recurring theme is that several trades have just worked in the same frame, so the checks look at both their work and its effect on the structure.
- Electrical rough-in — cable routing, mounting-box positions and junction boxes checked as accessible and sensibly located. The electrician certifies the wiring to AS/NZS 3000; we check what is visible before it is covered.
- Plumbing rough-in — pipe supports, penetration collars and any hydrostatic test evidence checked. The plumber certifies to AS/NZS 3500; we record what is exposed.
- Fire collars at fire-rated penetrations — collars present at pipe and service penetrations through fire-rated walls, per the fire-separation provisions of NCC Volume Two Part 3.7.
- Insulation installation — batts checked for full coverage with no gaps and no compression, since insulation only achieves its rated R-value when installed as intended, per AS 3999.
- Wall noggings for future fixtures — noggings in place where later fixtures — grab rails, wall-hung cabinetry, a wall-mounted TV — will need fixing into solid backing.
- Structural bracing not compromised — bracing, studs and bearers checked for notching or drilling by trades beyond what AS 1684.2 allows, which is one of the most common structural issues at this stage.
- Wet-area wall membrane — where the wet-area waterproofing to wall surfaces has been installed at this stage, its presence and condition are noted.
- Ceiling framing and noggings — ceiling framing and noggings checked for the cornice and for downlight and fan loads.
- Weather damage to the frame — any water damage to the frame from weather ingress during the lock-up phase, which needs to be dealt with before it is lined over.
Common pre-plaster defects and the standards they fail
The defects below are standards-based patterns rather than site-specific claims. Any inspector working to AS 1684.2 and the NCC checks for the same items.
- Bracing sheet notched for a cable run — an electrician cutting through a brace to route cable reduces the bracing capacity AS 1684.2 relies on. Notching beyond the allowance in AS 1684.2 is reported against it.
- Insulation compressed by plumbing — a batt crushed behind a pipe or squashed into a cavity loses R-value in that area. Insulation has to be installed uncompressed to deliver its rating under AS 3999.
- Missing fire collar at a penetration through a party wall — a service passing through a fire-rated wall without a collar breaks the fire separation the NCC Part 3.7 provisions require, which matters most on attached and party walls.
Why pre-plaster checks the frame, not just the rough-in
By pre-plaster the frame has passed through the hands of the electrician, plumber, insulator and sometimes the air-conditioning installer, each of whom needs to get services through it. AS 1684.2 sets limits on notching and drilling precisely because timber members lose strength when they are cut, and a brace notched for a cable no longer carries the racking load it was sized for. So the pre-plaster inspection is not only a rough-in check — it re-checks the structure the frame inspection signed off, because the trades that came after had every reason to cut into it.
When to book: after rough-in, before plasterboard
The pre-plaster window opens when the rough-in and insulation are complete and closes when the plasterboard goes up. Book too early and the rough-in and insulation are unfinished; book too late and plasterboard has already covered the cavity.
The workable point is with all the rough-in trades finished and the insulation in, immediately before the plasterer starts. Booking there means the cavities are complete and still open, so both the rough-in and the frame can be assessed and anything flagged corrected before it is lined. We turn the report around the same day for most inspections with photographs and references.
Pre-plaster, frame and the stages around it
Pre-plaster sits between the frame and the internal finishes. The frame inspection assesses the bare structure before the trades work in it; the enclosed inspection confirms the envelope is weather-tight around the same time; and the practical completion inspection is the final check at handover.
Frequently asked questions
When should I book a pre-plaster inspection?
Book the pre-plaster inspection once the electrical and plumbing rough-in is complete, the insulation is in and any fire collars are fitted — but before the plasterboard goes up. That is the last point where the inside of the wall and ceiling cavities is visible, so it is the last chance to see the rough-in and the frame behind it.
How long does a pre-plaster inspection take?
A single-storey home takes about an hour and a half to two hours because there is a lot to work through — every wall and ceiling cavity, the rough-in of each trade and the insulation. We photograph each item and issue the report the same day for most inspections.
What happens if the pre-plaster inspection finds a defect?
Each item is recorded with a photo, a location and the clause or standard it relates to — AS 1684.2 where a trade has cut into the frame, or the fire-separation provisions of the NCC for a missing collar. You forward it to your site supervisor before the plasterboard goes on, while the cavity is still open.
Do I attend the pre-plaster inspection?
No. We coordinate access with the site supervisor and attend in hi-vis and safety boots. You receive the same-day PDF report with photographs and references, and a follow-up call to walk through anything flagged.
How is a pre-plaster inspection different from a frame inspection?
The frame inspection assesses the bare structure before the trades work in it. The pre-plaster inspection happens after the electrician, plumber and insulator have finished, and checks two things: that their rough-in is correct, and that they have not compromised the frame — a notched brace or a drilled bearer, for example. Some builders combine the hold points; where they are separate, the pre-plaster catches what the frame stage cannot, because those trades had not started yet.
How does the pre-plaster inspection relate to the certifier's checks?
The licensed electrician certifies their work to AS/NZS 3000 and the plumber to AS/NZS 3500; those are trade certifications. Our inspection is an independent visual check of what is exposed at pre-plaster — insulation, fire collars, and whether the rough-in has damaged the frame — written for you, and it records items that trade sign-offs do not itemise.
How much does a pre-plaster inspection cost?
A standard residential pre-plaster inspection is $550 including GST across Brisbane and the Moreton Bay corridor. That covers the site attendance, the same-day photo-tagged report with the relevant references, and a follow-up call. Two-storey and larger homes are quoted individually.
Pre-plaster is the last cavity check. See the frame inspection before it, the waterproofing inspection that follows, or the full construction stage inspections sequence through to handover.
Check the Cavity Before It's Lined
Book after rough-in, before plasterboard
Book your pre-plaster inspection while the rough-in, insulation and frame are still open to view.
Your build, stage by stage
Every new home moves through the same inspection sequence. See where this stage fits and jump to the ones before and after it.