1️⃣ Poor Suction from Rangehoods or Exhaust Fans

If your rangehood barely pulls steam or smoke, or your bathroom fan feels weak, airflow restriction is the issue — not the motor.

• Typical Cause: Generic plastic vents or mushroom-style caps with retro fitted mesh( most common cause,) or ducting squashed down in the roof space.
• Reality Check: Many builder-supplied vents are not designed for 150 mm systems, despite being installed that way.
• DVA Solution: Our DV-350LP Hi-Flow Roof Vent and EV-400 Dual Eaves Vent maintain true 150 mm open flow — tested to deliver over 900 m³/h with zero mesh blockage.

2️⃣ Excessive Noise or Motor Strain

A noisy or humming exhaust fan usually means back pressure is building up — the fan is fighting against poor vent design.

• Typical Cause: Long, twisted duct runs feeding into small, restrictive, untested vents, mushroom-style caps with retro fitted mesh( most common cause,)
• Result: The fan works harder, airflow drops, and motor lifespan shortens.
• DVA Solution: Low-restriction vents engineered and tested to lower static pressure for quieter, longer-lasting performance.

3️⃣ Condensation, Moisture, or Mould on Ceilings

Poorly performing vents allow moisture to linger in bathrooms or kitchens, leading to mould, swelling plasterboard, and ceiling stains.

• Typical Cause: Vent terminations that leak or don’t exhaust fully outdoors, or vents clogged by dust, insects, ormushroom-style caps with retro fitted mesh( most common cause,)
• DVA Solution: Replace outdated wall or eaves vents with bushfire-rated, insect-proof designs like the DV350LP which maintain high airflow while keeping the elements out.

4️⃣ Lingering Cooking Odours

If you can still smell dinner hours later, your rangehood system probably isn’t exhausting properly.

• Typical Cause: Restricted air exit, blocked ducting, or non-compliant vent designs that choke airflow.
• DVA Solution: A Hi-Flow Roof Vent such as the DV-350LP dramatically improves extraction efficiency, removing grease vapour and odours faster while reducing noise.

5️⃣ Corrosion, Rust, or Damaged Mesh

Discolouration or rust around vents isn’t just cosmetic — it’s a performance and safety risk. Rusted mesh reduces airflow and voids any bushfire compliance.

• Typical Cause: Thin, mild-steel imports or powder-coated aluminium without weather testing.
• DVA Solution: Every DVA vent is made from 304 Stainless Steel or BlueScope Colorbond®, cyclone-rated, and BAL-12.5 to BAL-40 compliant.

⚠️ The Real Problem: Untested, Non Conforming Imported Vents

The Australian building industry is flooded with cheap, imported roof vents that are never airflow-tested, have no CSIRO or BAL certification, and in many cases, breach NCC requirements.

They restrict airflow, increase condensation risk, and expose builders and homeowners to warranty and compliance issues.

To make matters worse, once a home is completed, the roof is no longer safely accessible — meaning most owners and builders can’t visually inspect what’s been installed. Generic vents on your roof quietly failing due to cracked rubber collars, corrosion, or water ingress due to sub standard installation practices( and cheap silicon)

By the time the symptoms appear — mould, ceiling stains, or motor failure — it’s too late. The damage has already spread inside the roof cavity, leaving the homeowner with costly repairs for the homeowner.

At Dragon Vents Australia, we believe every vent should be tested, certified, and built to last — because compliance and performance should never depend on what can’t be seen.

 Why Imported Generic Roof Vents Fail

Most Australian homes are fitted with generic roof vents — bulk-supplied to builders or sold online — that lack any verified performance data. These vents are typically untested, uncertified, and non-compliant with both bushfire (BAL) and NCC standards.

Unlike tested, engineered systems, many imported vents depend on flimsy rubber collars that crack or separate as roofs expand and contract with the seasons. Once that happens, leaks begin — allowing moisture to track under flashing, leading to ceiling damage, corrosion, and costly repairs. Generic vents restrict airflow and seal poorly, they quietly choke exhaust systems, strain rangehood motors, and trap condensation i — creating long-term risks for homeowners, builders, and insurers alike.

✅ The DVA Difference

The DV-350LP was designed to eliminate these failures. Built for strength, precision, and long-term performance, it’s purpose-engineered for corrugated tin roofs pitched at 12° and above (the most common pitch in Australian homes being around 25°). Once installed, there’s no movement, tearing, or leak path, even as the roof flexes over time.

• ✔️ Independently airflow-tested (> 900 m³/h @ 150 mm)
• ✔️ BAL 12.5 – BAL 40 certified
• ✔️ Cyclone and coastal resistant
• ✔️ Solar-compatible low-profile design
• ✔️ Australian-engineered for real-world conditions