If you live in a 1970s or 1980s brick-veneer home anywhere in the Illawarra, from Dapto to Corrimal, Berkeley to Figtree, you are living in a property type that has specific, well-documented mould vulnerabilities. These homes represent the dominant housing form across Wollongong’s suburban expansion era, and their combination of construction methods and materials creates conditions that drive persistent mould problems even in otherwise well-maintained properties. Understanding these vulnerabilities is the first step to addressing them. For older fibro homes, see our separate guide on fibro and asbestos-era homes.
Quick Answer (BLUF)
1970s, 80s brick-veneer construction in the Illawarra typically has no insulation in the wall cavity, no sarking under the roof tiles, and uses compressed fibre cement sheet (not water-resistant) in wet areas. These features combine with the Illawarra’s coastal humidity to create cold walls, condensation problems, and wet-area failures. The solutions are specific to these construction details.
What Is Brick-Veneer Construction?
Brick veneer is a construction method where a single leaf of brick forms the external skin of the building but is not load-bearing, the actual structure is a timber frame set back from the brick by a narrow cavity (typically 50-75mm). The frame carries the load of the roof and floors. The cavity was originally designed to drain any moisture that penetrated the brick leaf to the outside.
This system works well when it is built and maintained correctly. The problems arise from how 1970s, 80s construction shortcuts interacted with the Illawarra’s climate.
Why These Homes Have Mould Problems
No Wall Cavity Insulation
In the 1970s and into the 1980s, insulation in wall cavities was not required by the Building Code and was rarely installed. The result is an external wall system with very low thermal resistance. In Wollongong’s mild-to-cool winters, the inside face of the plasterboard (the interior wall lining) gets cold, sometimes only a few degrees above outside temperature in an unheated room.
When warm, humid indoor air meets a cold wall surface, it reaches its dew point and moisture condenses. In a humid coastal suburb, this condensation cycle repeats every night in winter and on cool summer nights when sea breezes drop temperatures. Over time, the repeated wetting of the inner plasterboard face drives mould.
Weep Holes Blocked or Absent
Brick veneer walls rely on weep holes at the base of the brick course to drain moisture that enters the cavity. In many 1970s homes, these weep holes are blocked with mortar (a construction error) or have been subsequently filled by well-meaning owners concerned about insects. Blocked weep holes trap moisture in the cavity, which wicks into the timber bottom plate and base of the internal plasterboard. Our blocked weep holes guide covers how to spot this specifically and what clearing or restoring them involves. A more recent version of the same problem shows up after a render or repaint job runs straight over the weep line; our guide to mould after rendering or repainting covers that specific trigger and what treatment involves.
Damp-Proof Course Failures
The damp-proof course (DPC) at the base of the brick work should prevent rising moisture from the foundation from entering the wall cavity. In homes of this era, the DPC is typically bituminous felt or polyethylene sheet, materials that can degrade, crack, or fail after 40+ years. A failed DPC allows ground moisture to wick up through the brickwork and into the base of the wall cavity.
Sub-Standard Wet Area Substrates
Pre-1990 bathrooms in brick-veneer homes were almost universally tiled over standard fibre cement sheet or, in some cases, standard plasterboard. These substrates absorb water when grout or caulk fails. Unlike modern wet-area fibre cement (specifically treated to resist moisture), these materials degrade and grow mould when wetted repeatedly.
No Sarking Under Roof Tiles
Sarking, a reflective foil membrane installed under roof tiles, was not standard practice in this era. Without sarking, wind-driven rain can penetrate between tiles and reach the insulation and ceiling space directly. In Illawarra storms with westerly squall winds behind them, this is a regular occurrence.
Homes of this era with an added raked living-room extension face a related but separate issue: a cathedral or skillion ceiling has little or no cavity above it at all, so condensation forms directly against the plasterboard rather than in a ventilated roof void. Many of these same homes had a skylight added to that raked ceiling to brighten an otherwise dark extension, and the skylight frame itself becomes its own condensation point; our skylight condensation mould guide covers why that happens and what fixes it. A different hidden-moisture problem affects two-storey homes with a cantilevered balcony or a balcony over a garage: our guide to balcony membrane failure and the room-below mould pattern covers how a failed membrane can show up as mould a full floor below the balcony itself. Homes of this era commonly added a split system air conditioner to a bedroom or living area too, and the musty smell that comes from the unit itself rather than the wall is a separate issue again; our guide to split system mould cleaning versus a professional service covers how to tell the two apart.
Common Mould Locations in These Homes
Given the above, the most predictable mould locations in 1970s, 80s Illawarra brick-veneer homes are:
- South-facing bedroom walls, cold external wall, condensation on the plasterboard inner face, mould behind furniture pushed against the wall
- Base of external walls, rising damp from a degraded DPC or blocked weep holes, appearing as tide marks and mould at floor level
- Bathroom walls and floor, failed grout or caulk, water penetration into the substrate, mould behind or beneath tiles
- Ceiling at eave line, moisture tracking from the roof space where sarking is absent
- Under-sink cabinets, slow drip from older copper or galvanised plumbing, often undetected for months
- Under-stair storage cupboards built against an external wall, where a blocked weep hole or cavity moisture problem can show up first in a rarely opened storage space rather than the room itself; our guide to mould in wine cellars and under-stair storage covers this specific enclosed-space pattern
What Remediation Involves for These Properties
Remediating mould in a 1970s, 80s brick-veneer Illawarra home requires addressing both the mould and the underlying construction vulnerabilities:
- Professional mould inspection with thermal imaging to identify cold wall areas, moisture pathways, and all affected areas, book an inspection
- Targeted remediation of affected plasterboard, wet area substrates, and any contaminated insulation, mould remediation service
- Wet area upgrade if the bathroom substrate is compromised, replace with water-resistant fibre cement sheet, retile, and use epoxy grout
- Weep hole inspection and clearing, should be done by a qualified builder
- Wall cavity insulation, a retrofit cavity wall insulation (blown mineral wool or polystyrene bead) dramatically improves the thermal performance of the wall, raising the inner face temperature and eliminating most condensation
- Sarking installation is only practical during a re-roof, but if the property is due for new tiles, sarking should be specified
FAQs
Is it worth investing in remediation on a 50-year-old brick-veneer home?
Yes, provided the structure is sound. Brick-veneer construction is fundamentally durable, the mould problems in these homes are driven by addressable details (insulation, DPC, weep holes, wet area substrates), not the construction system itself. Remediation combined with targeted improvements gives these homes decades more serviceable life.
How do I tell if my DPC has failed?
A failed DPC shows as efflorescence (white salt deposits) on the external face of the brick at low level, or as damp staining on internal plasterboard at floor level. A building inspector or experienced builder can confirm this with a visual assessment and moisture meter readings.
Can I add insulation to the wall cavity of my existing brick-veneer home?
Yes, retrofit cavity wall insulation involves drilling holes in the mortar joints, blowing insulation material (typically polystyrene bead or mineral wool) into the cavity, and re-pointing the mortar. It is a well-established technique, takes one day for a typical home, and makes a significant difference to both thermal comfort and mould risk.
My home was built around 1980, should I check for asbestos before remediation?
Yes. Fibro (fibre cement) sheeting, floor vinyls, and some textured ceiling coatings in homes built before 1990 may contain asbestos. Any material that may be asbestos-containing should be assessed by a qualified asbestos assessor before disturbing. See our guide on fibro and asbestos-era homes.