Are open cavity vent returns and exposed pipes normal in new construction?
Open-cavity plenum returns and exposed bathroom pipes are shortcut building methods used to save installation time and material costs. These makeshift setups compromise indoor air quality, create noise issues, and expose plumbing lines to potential damage inside the HVAC pathway.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 18.4× more often in r/hvacadvice than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Seeking second opinions onlineDid this help you?
- 2seal the gap using rolled mastic sealant or tapeDid this help you?
- 3Applying mastic or tape to seal the seamsDid this help you?
- 4Contacting the HVAC installation company directlyDid this help you?
- 5Consulting an HVAC expert instead of relying on a home inspectorDid this help you?
- 6Leaving the duct open to condition the crawl space or sealing it if the space is ventedDid this help you?
- 7Removing tape from vent seamsDid this help you?
- 8Taking pictures of connections to inspect manuallyDid this help you?
- 9Considering calling a plumber for a safety checkDid this help you?
- 10Applying foil tape over the drilled holeDid this help you?
- 11Putting a blob of high temperature silicone over the holeDid this help you?
- 12Using a removable metal plugDid this help you?
- 13asking for advice on online HVAC forumsDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“We noticed in the one return vent we can see visible gaps on the one return panning (you can see light straight through the vent into the upstairs).”source ↗
“There are also some slight gaps on some of the corners of the metal ductwork itself. My wife and I are new to all this so we didnt know what is considered normal and what could potentially be an issue.”source ↗
“While doing so I noticed this open run. Is it supposed to be there? It seems counter intuitive to be taping all these joints if there's an open run like this.”source ↗
“I recently had someone come to my house to extend the exhaust port for my furnace so it isn't too close to the intake port. Will I run into any problems in the future? Is this setup correct?”source ↗
Where this came up
People with this problem also raised
- 5How to tell if a ridge vent was installed correctly
- 28What to do when an HVAC installation fails inspection
- 4Can you service an HVAC system with leak seal in it?
- 3Why a clogged drain line diagnosis doesn't make sense
- 2Is the builder supplied HVAC system sufficient?
- 8How do I reconnect a disconnected HVAC duct?