HVAC Penetration Leak Repair

HVAC penetrations are some of the most service-heavy areas on a commercial roof. They are exposed to vibration, mechanical service, water, and temperature swings, which makes them a common leak source on both PVC and TPO membranes.

The repair has to do more than cover the visible opening. It has to restore the transition around the equipment and reduce the chance that the same problem returns.

Why HVAC leaks happen

Common causes include:

• movement from equipment vibration,
• weak flashing at the curb or base,
• water collecting near the unit,
• or wear from repeated maintenance visits.

If the same HVAC area keeps leaking, the issue is usually not random.

What to inspect

Inspect the whole HVAC zone:

• the curb edges,
• the flashing transition,
• nearby seams,
• and any old repair layers around the unit.

If the roof has ponding water nearby, that makes the detail even more vulnerable.

Repair approach

The repair should focus on:

1. cleaning the transition,
2. rebuilding the seal around the curb or penetration,
3. reinforcing the surrounding membrane,
4. and checking the nearby water path.

HVAC leak repairs fail when the contractor only closes the visible gap and leaves the movement problem untouched.

Why this area needs more attention

Compared with other penetrations, HVAC details see more traffic and more equipment service. That means they need regular inspection, not just emergency repair.

Practical takeaway

If the HVAC area leaks once, it should be treated as a maintenance zone for the rest of the roof life. That simple habit prevents repeat callbacks and keeps the detail easier to manage.