Shed problems and early warning signs.
Sheds do not fail suddenly. They tell you for two or three years first, and almost nobody is listening. Here are the eight signs we see on Casey sheds, what each one actually means, which are cosmetic and which are the ones you fix now.
What your shed is trying to tell you.
1. Rust bleeding at the slab line.
The most common call we get. The bottom 100mm of the wall sheet is the wet zone, and if soil, mulch, turf or a pile of clippings is banked against it, the coating never dries. Casey’s winters give it months to work. Cosmetic at first, structural by the time it perforates. Cost to fix now: nothing, pull the dirt back and leave a 50mm to 75mm air gap. Cost to fix in five years: new bottom sheets on every affected wall.
2. A roller door that has started to bind.
A door that ran fine for six years and now catches is telling you the opening is out of square. That means the frame moved, and the frame moved because the slab moved. Classic on Class M reactive clay at the end of a dry summer when the clay shrinks and the slab edge settles. If it binds in February and frees up in July, that is seasonal movement and it needs an engineer, not a door bloke.
3. A stepped or through-edge slab crack.
Fine crazing across the floor is normal. A crack that runs into and through the edge beam, one you can drop a 5c coin into, or one with a vertical step where one side is proud of the other, is not. Those are reactive clay symptoms and they mean the slab was not designed to the soil class it is sitting on. Fixable in some cases with underpinning, expensive in all cases.
4. Water dripping inside on a clear morning.
Not a leak. Condensation. The roof sheet radiates heat to a clear winter sky, drops below the dew point, and the moisture in the shed air condenses on the underside. About 9am when the sun hits it, it releases all at once onto your tools. Every uninsulated steel shed in Melbourne does it. Anticon blanket at build time plus a whirlybird and soffit vents at $280 to $580 solves it. Retrofitting the blanket costs several times more.
5. Rust weeping down from the screw heads.
The fastener class was wrong, or the neoprene washer has perished under Melbourne UV and the screw is sitting in its own puddle. Red streaks running down otherwise perfect Colorbond. The sheet is fine. The screws are not, and every one of them is a hole in your roof. On a shed of any size this is a full re-stitch, and it is the reason we use Class 3 coated fasteners inland and Class 4 near Western Port.
6. Daylight at the apex or the gable end.
Missing or lifted flashing. Water is running down the inside of the column webs where you cannot see it, which means the base plates and the bottom of the columns are wet more often than they are dry. Cheap to fix, quietly destructive if you leave it. Look up at the ridge on a sunny day with the door shut.
7. Sheeting that flutters or drums in wind.
Purlin spacing, screw pattern or both are wrong for the wind classification of the block. Casey is AS 1170.2 Region A, but exposure varies enormously: a sheltered Hallam block is N2 and a ridgeline at Harkaway or Narre Warren North can be N3 or N4. A shed engineered for the former and built on the latter drums in a southwesterly, and drumming is the sound of the fasteners working themselves loose. This is the one that turns into a storm claim.
8. Gutters overflowing at the same spot every winter.
Gum leaves, and Casey has plenty of them, particularly north of the freeway. A blocked gutter holds water against the fascia and the top of the wall sheet all winter, and the overflow dumps against the slab edge, which brings you back to problem one. Two cleans a year. It is the highest-return maintenance there is.
Worked example: 9m x 6m workshop, Hampton Park, caught at year nine (2026 pricing).
Rust at the slab line down the south wall, screw-head weeping across the roof, condensation staining on the frame. Structure sound, frame square, slab fine. The repair scope:
- Full re-stitch, all roof and wall fasteners replaced with Class 3 = $2,400
- Replace six bottom wall sheets on the south elevation = $1,850
- Regrade the ground line, drainage swale away from the slab edge = $1,200
- Retrofit whirlybird and soffit vents = $520
- Gutter clean, downpipe realignment, apex flashing repair = $680
Total: $6,650 on a shed that would cost about $24,000 to replace today. Worth doing, comfortably. The same shed left another six years is a rebuild, because once the columns lose section at the base plates there is nothing to re-sheet onto. That is the whole point of catching it early. What drives the lifespan in the first place is on our Colorbond shed lifespan page, and the routine that prevents most of this is on the maintenance and aftercare page.
When it is a rebuild, we will say so.
Sheeting and fasteners are almost always worth replacing. Frames and slabs usually are not. Our rough rule: if the repair quote gets past about 60% of a new build, rebuild, because the new shed comes with a permit, an AS 1170 engineering certificate and a warranty, and the patched one comes with none of those. Replacement garages are on the garages and workshops page, and if the damage came from a storm rather than time, read the insurance claims page before you touch anything. Local site notes for that part of the municipality are on the Hampton Park page.
Shed problem questions.
Why is my shed rusting at the bottom of the wall?
Because something is holding water against it. In Casey it is nearly always one of four things: garden beds or mulch banked up over the bottom of the sheet, turf grown up against the wall, grass clippings piled along the base, or a slab poured without enough fall so rain splashes back and sits. The coating on Colorbond needs to dry out between wettings. Where it never dries, it goes eventually. The fix is usually free: pull the soil back to leave a 50mm to 75mm gap below the bottom edge of the sheet and let air get to it.
Why does my roller door suddenly stick?
A door that worked for years and now binds is telling you the opening is no longer square, and that usually means the frame has moved because the slab has moved. On Class M reactive clay this classically shows up at the end of a long dry summer when the clay shrinks and the slab edge drops. If the door binds in February and frees up in July, that is seasonal slab movement and you want an engineer to look at it rather than a door technician. If it binds all year and got worse gradually, it is more likely worn tracks or a failing spring.
Is a crack in the shed slab serious?
Depends where it runs and how it behaves. Fine surface crazing and short shrinkage cracks in the middle of the floor are cosmetic and normal, particularly on a slab poured on a hot windy day. What is not normal is a crack that runs to and through the edge beam, a crack you can slide a 5c coin into, a crack with a step in it where one side sits higher than the other, or a crack that opens and closes with the seasons. Those are structural symptoms on reactive clay and they need an engineer, not a bag of filler.
Why does my shed drip water inside when it isn’t raining?
That is condensation, not a leak, and it is very common in Casey through winter. A cold clear night drops the roof sheet below the dew point, moisture in the air condenses on the underside, and at about 9am when the sun hits it, it lets go all at once onto whatever is beneath. Every uninsulated steel shed does this. The fix is anticon blanket under the roof sheeting, which you install at build time for far less than retrofitting it, plus ventilation: a whirlybird and soffit vents at $280 to $580 lets the moist air out instead of trapping it.
When is a shed beyond repair?
Sheeting and fasteners are almost always worth replacing. Frames and slabs usually are not. If the C-section columns have lost section at the base plates, if the frame is out of square enough that new sheets will not lie flat, or if the slab is moving seasonally and taking the frame with it, the honest advice is to demolish and rebuild rather than chase it. The rough test: if the repair quote passes about 60% of a new shed, rebuild, because the new one comes with an engineering certificate, a permit and a warranty and the repaired one comes with none of those.
Shed assessments across Casey.
Not sure if it is cosmetic or structural?
We will look at it and tell you straight, including when the answer is that it needs nothing.