Undersized Gutter
Undersized Gutter is a cosmetic drainage defect SURE inspectors have documented across 1 inspection report.
Causes
- Downpipe dimensions (50 mm diameter) are unlikely to comply with AS/NZS 3500.3, leading to insufficient capacity.
- Gutter dimensions (100 mm deep × 50 mm wide) are unlikely to comply with current performance requirements for rainwater disposal under NCC 2022 Volume Two, Part H2D and AS/NZS 3500.3:2021.
Symptoms to look for
- Visible evidence of moisture penetration to the eastern wall in the office area
- Contributing to overflow and water ingress during high rainfall events
- Gutter surcharge
- Increased risk of surcharge and overflow into adjacent building elements
- Limited flow capacity
Remedies
- Replacement with a larger diameter downpipe (e.g. 75 mm or greater, subject to calculation) is recommended.
- The downpipe sizing should be reviewed and recalculated in accordance with AS/NZS 3500.3:2021.
- A licensed plumber should assess the gutter size against AS/NZS 3500.3 using the applicable roof catchment area and rainfall intensity.
- Upgrade to a compliant gutter profile may be required to prevent overflow during heavy rainfall.
Include this check in your next inspection.
Typically a low-severity finding, but worth documenting before maintenance work. Every SURE inspection includes 12 months of free advice.
Curated entries in Drainage
- Curated 1–4/5Undrained Air Conditioner Overflow
Split-system and ducted air conditioners produce condensate that must be piped away from the building. Where the overflow line terminates against the wall or discharges onto soil at the perimeter, repeated wetting creates conducive conditions for subfloor moisture, termite activity, and rising damp in adjacent masonry or framing.
- Curated 1–4/5Inadequate Surface Water Drainage
Where surface water cannot drain freely away from the building perimeter, it accumulates against footings and walls, creating persistent soil moisture that is a primary conducive condition for termite activity and footing movement. The BCA requires finished ground levels to fall away from the building at a minimum 1:100 grade for at least 1 metre at every external wall.
- Curated 1–4/5Downpipes Not Connected to Storm Water
One or more downpipes discharge directly onto the ground at the building perimeter rather than into a stormwater system. Water concentrates against footings, raising the risk of footing movement, rising damp, and termite conducive conditions - we find this in 22.1% of all Perth inspection reports.
- Curated 1–3/5Debris in Gutters
Leaf litter, dirt, and organic matter accumulating in gutters blocks downpipes and causes water to back up, overflow, and saturate fascia and eave linings. We see this in 17.5% of all Perth inspection reports - one of the most frequent maintenance defects on the books.
- Curated 1–3/5Uneven Pathways
Differential settlement of concrete or paved pathways creates raised or sunken sections that direct surface water toward the building rather than away from it. Our inspectors record this in 7.86% of all Perth reports. Beyond water ponding and potential moisture ingress at the perimeter, uneven surfaces present a trip-hazard that may engage liability considerations for vendors and landlords.
- Curated 2–4/5Stormwater Drainage Directed Towards Building
Site grading or paving directing stormwater runoff towards the building foundation rather than away from it. Causes subfloor moisture accumulation, rising damp, and potential foundation movement on reactive soils.