Understanding damp exterior walls in Perth
Exterior wall waterproofing stops rain soaking through brick or render into the rooms behind. In Perth it tends to show after winter fronts: a low damp patch inside, peeling paint, mould behind furniture or water lying against the footing. The fix starts by finding where water gets in.
Who this exterior wall work suits
It suits rendered homes with fine cracks, brick walls that stay dark long after rain, and homes where garden beds, paving or downpipes push water against the base. A room that smells musty each winter and dries by summer points to the outside wall, though plumbing and roof leaks need ruling out.
What a dry interior wall looks like
Once the outside is sealed and water drains away, the inside face slowly dries. Paint stops bubbling, skirting boards stop swelling and the musty smell fades. Thick masonry dries slowly, so allow time before judging the result or repainting indoors.
Membrane, coating and drainage on exterior walls
Cracked render usually needs repair before a waterproof coating, porous face brick may suit a clear repellent, and walls with soil against them may need a membrane. Where external above-ground membranes fall under the NCC Deemed-to-Satisfy provisions, they must comply with AS 4654.1 and AS 4654.2.
Why drainage at the base decides the result
Water pooling against a wall keeps feeding damp however good the coating is. Check whether paving falls towards the house, garden beds sit above the damp course or downpipes empty at the footing. Any change to stormwater or drainage plumbing needs licensed professionals.
Contract checks before work starts
Work that is exempt from a permit must still meet building standards, so a cheap coating job is no shortcut. For a waterproofing contract covered by the Home Building Contracts Act, the deposit is capped at 6.5%, and later payments can only cover work done or materials already supplied.
Before you get in contact about a damp wall
Note which room shows the damp, how high it climbs and whether the wall is face brick, rendered or block, plus your suburb. Mention what sits against the outside, such as paving, a garden bed or a downpipe, and whether it worsens after one heavy storm or only through a long wet spell.
Exterior Wall Waterproofing Services We Offer
✓Rendered Wall Waterproofing
For render with hairline or open cracks letting rain reach the masonry behind. Cracks are repaired first, then a waterproof coating goes on.
✓Face Brick Sealing
For exposed brick that soaks up rain and stays dark for days. A clear repellent can cut absorption while keeping the brick's look.
✓Walls Below Garden Level
For walls where soil, garden beds or paving sit higher than the inside floor, which usually calls for a membrane on the outside face.
How it works
- 1
Trace the damp
Map where damp shows inside and compare it with the outside: cracks, gutters, downpipes, garden beds and paving levels. This separates rain getting through the wall from plumbing leaks or condensation.
- 2
Sort out the drainage
Redirect downpipes, pull back garden beds or regrade paving so water runs away from the footing instead of pooling against it.
- 3
Repair and treat the wall
Cracks and loose render are repaired and the surface cleaned, then a coating, repellent or membrane suited to that wall is applied.
- 4
Let it dry before painting
The product has to cure and the masonry has to dry out. Mould cleaning and repainting inside come once the wall has had time to dry.