Pakenham Building
Inspections

A plumbing vent that stopped in the roof space

Why a waste stack vent has to go through the roof, found on a Pakenham pre-purchase inspection.

Pakenham 3810 · 17 March 2026

In short: From inside the house nothing looked wrong. From the roof space, the plumbing vent simply ended under the tiles.

What a vent stack does

The drainage system needs a vent that runs up and out through the roof. It lets air in and sewer gases out, and keeps the water seals in traps from being sucked dry.

What we found

In an established Pakenham house the waste stack vent stopped inside the roof space instead of being carried through the roof. Sewer gas from the drains could collect in the roof.

Why it is easy to miss

Nothing shows from inside the rooms. You only see it from the roof space, which is why we go up there whenever the manhole allows.

The fix

A plumber extends the vent through the roof with a proper flashing. It is a modest job, and useful to know about before you buy.

Other roof space items

On the same inspection insulation had been pushed aside in parts of the ceiling and several roof tiles were cracked.

Written by our local inspection team from work carried out in Pakenham. Licensed building practitioners, Building & Plumbing Commission registration CDB-U 53425.

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FAQ

Questions Pakenham owners ask about this

Is it a health hazard?

We recorded it as a major item because waste gases can build up in the roof space. A plumber should correct it.

Would a building and pest inspection find this?

Yes, the building part covers the roof space where accessible.

Do you test the plumbing?

No. We look at what is visible. A plumber can test the system.

Can I use it to negotiate?

Many buyers do. It is a specific item with a known fix.

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