HVAC lineset leaking through the roof
When HVAC linesets penetrate the roof rather than exterior walls, they often cause ceiling leaks that installers blame on unrelated roof issues like valleys. This leaves homeowners struggling to find a reliable fix without paying thousands more for contractor repairs.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 35.0× more often in r/Roofing 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.
- 1Applying temporary sealants like NP1 or Duralink around the penetrationDid this help you?
- 2Installing a zipper boot or pitch pan with pourable sealerDid this help you?
- 3Rerouting the lineset entirely through the interior, garage wall, or soffitDid this help you?
- 4Taking boarding off to inspect the water ingressDid this help you?
- 5Asking the original contractors to come back and address the leakDid this help you?
- 6Applying caulking or sealant over the holes and flashingDid this help you?
- 7Waiting for the rain to stopDid this help you?
- 8putting out buckets to catch waterDid this help you?
- 9deciding whether to attempt a DIY roof repair or hire a professional rooferDid this help you?
- 10trying to take photos from the yardDid this help you?
- 11Getting roofers to propose replacing asphalt shingles and torch down roofsDid this help you?
- 12Checking permit records to determine the age of the roofDid this help you?
- 13investigating the source of the leak by opening up the ceilingDid this help you?
- 14inspecting the area with protective gear like gloves, a face shield, and a plastic sheetDid this help you?
- 15getting a ladder to inspect and photograph the eaves and shinglesDid this help you?
- 16Unplugging and removing affected itemsDid this help you?
- 17Placing a bowl underneath to catch dripsDid this help you?
- 18Waiting until the next morning for maintenance to respondDid this help you?
- 19Sealing where the shingles meet the vent on the backside and down the sides as a temporary fixDid this help you?
- 20Removing and reinstalling the vent correctly using guides or hiring a roofing company/handyman serviceDid this help you?
- 21Applying temporary sealants like rubberized asphalt spray or 'thru the roof' product over the leaking areaDid this help you?
- 22Removing old cracking tarDid this help you?
- 23Inspecting flashing and chimney cricketsDid this help you?
- 24flip the breaker for that room and leave it off until everything is dryDid this help you?
- 25Asking online for DIY guidance on installing kickout flashing or replacing componentsDid this help you?
- 26Applying roof patch tape instead of tar to prevent a sticky mess for the roofersDid this help you?
- 27Using a tarp as a temporary coverDid this help you?
- 28Fixing the leaking pipe or fixture immediatelyDid this help you?
- 29Notifying the landlord and waiting for professional repairsDid this help you?
- 30Installing a heated coil to prevent ice damsDid this help you?
- 31Having a different contractor fix a botched roof replacementDid this help you?
- 32Considering building a false roof on top of the rubber roofDid this help you?
- 33Waiting until ladders are available to inspect the roof or atticDid this help you?
- 34Applying sealant to the storm collar yourselfDid this help you?
- 35Having a professional remove the unused chimney and patch the holeDid this help you?
- 36Ignoring potential hidden water damage behind the drywallDid this help you?
- 37Waiting for the new roof and gutters to be installed to see if it fixes the issueDid this help you?
- 38Trying to determine the cause by asking online or consulting roofersDid this help you?
- 39Ignoring the leak temporarily due to other time commitmentsDid this help you?
- 40Waiting until parts of the ceiling fall downDid this help you?
- 41Applying roofing patch/sealant (e.g., Henry's wet patch) to the leak areaDid this help you?
- 42Removing wet insulation, drying the area with fans, and setting up buckets with boards in the attic to catch dripping waterDid this help you?
- 43Using sheet metal slid under damaged tiles or shooting tile secure under slipped tilesDid this help you?
- 44Hiring a roofer on the side or using company financing (e.g., 0% interest loan offers)Did 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.
“It’s leaking, and I’m sick and tired of putting out that buckets.”source ↗
“Too scared to get up on the roof as it’s like 30ft but I think I found the culprit.”source ↗
“Since the install it's started leaking. Never before, I'm absolutely sure.”source ↗
“Asked them to come back, and they're saying it's an issue with the valley, and it's £4k more to repair. Not in the scope of the original work.”source ↗
“We don't have £4k and now we have a roof which was leakier than at the start.”source ↗
“Well investigated a wet spot saw a nail dropping water from the attic went to investigate and it got worse and worse. Not really sure what to do and I am feeling kind of dumb because I listened to a family member about using some Henry’s wet patch when I am doubting it did or will do anything.”source ↗
“Having consistent leaks due to rain and roofers have proposed to replace both the asphalt shingles and torch down roofs.”source ↗
“Wanted to see if the pictures of the roof indicate a roof replacement is merited.”source ↗
“Any ideas on why roof is leaking around the chimney? Going to get roofer when i get money saved but maybe someone can tell me how to stop leak for now.”source ↗
“I can't get on the roof because I don't have a tall enough ladder and I don't trust myself on it.”source ↗
“Water is dunning down the I flashing roof in begins the corner siding. Should there be a flashing kick out there? If so does it go under the corner piece too or should that be replaced?”source ↗
“It started leaking again today. The slope on this rubber roof on the extension isn’t steep at all.”source ↗
“water is leaking from the roof, down the pipe and into the basement (on the outside of the pipe) whenever it rains.”source ↗
“My husband and I are not very handy so we called a roofer but he said that he would need the chimney removed first and then he can patch the hole.”source ↗
“U got the same roof as I do. Unfortunately somehow the tiles have moved or cracked.”source ↗
“Since it’s leaking, I’d still have the vent pulled and checked rather than just caulked.”source ↗
“The places where he pierced the roof with AC electrical box and the place where he decided to insert a “vent” are leaking like crazy.”source ↗
“Once it cools down a bit I want to take the “vent tube” out, and see if I can properly secure the switch box to fix the leaks. It all being in the valley makes me question if I can do it myself.”source ↗
“Our roof ridge is leaking from possible splashback.”source ↗
“The roofers who replaced our roof is saying that because of our steep roof, we should have the roof ridge taken out in replace of roof vents.”source ↗
“Is there truth to that or did they botch the installation and don't want to fix the real problem?”source ↗
“Newish roof installed 3 yrs ago for an insurance claim, now having a leak in the ceiling.”source ↗
“i suspect it's due to roofers not wanting to pull out the old drip edge and putting a new one in over the top causing the metal to bend.”source ↗
“I am pretty pissed at this workmanship.”source ↗
“My roof leaked with a similar chimney but my flashing was better just really old.”source ↗
“I got water in my attic from the storms here in NJ this weekend.”source ↗
“The water only seems to be down the center under the ridge vent.”source ↗
“So for background, I’m currently getting a new roof in two days - thankfully right as I noticed a ceiling leak in my living room.”source ↗
“I also noticed that when we get a decent amount of rain, water has been dripping from my soffit and hitting my living room window. What is causing this? Would a completely new roof fix this issue?”source ↗
“Unfortunately, there’s no attic above my living room so no way for me to check.”source ↗
“Sadly, I don’t have a tall enough ladder to reach the second story safely although I might be able to set up the one I have and get a pole stick”source ↗
“Most of my leaks were actually from bad flashing.”source ↗
“Within the last year we've noticed a ceiling drip in a spot in the house below a roof location with HVAC lineset running through.”source ↗
“Obviously I'd prefer the cheapest/simplest option that fixes the problem, but I'd also prefer to 'do it right' and not just bandaid things.”source ↗
“I’ve got water coming in around this bathroom fan vent.”source ↗
“So I came home from work around 3:30pm to my paper lamp above my coffee table fully brown on the bottom and water on my table but nothing on the table that could’ve spilled.”source ↗
“What I am wondering: Is there any risk for my ceiling to collapse or anything before maintenance sees my request in the morning and comes?”source ↗
“I just wanted to post for reassurance mostly since I’ve never dealt with this and it happened at a terrible time when maintenance won’t come til tomorrow”source ↗
“had a leak in ceiling after some heavy rain and it’s near a light and I’m worried if this would be a problem with the electrical and end up causing a fire or something.”source ↗
“I'm in need of a new roof, but seeking a temporary fix to prevent a pesky leak.”source ↗
“The solar company came an patched it 5 years ago where it was mounted, but the leak is back.”source ↗
“I'm wondering if I can buy a bucket of tar and spread it on the shingles on and above the leak without doing any damage when it's time to rip them off for more.”source ↗
“It was a slow leak from the light fixture when we moved in May, scale from 1 - 10, how hosed are we?”source ↗
“Like a 8. That looks like severe damage.”source ↗
“Noticed this morning paint in living room is bubbling in one spot but going pretty far down the wall.”source ↗
“Paint on ceiling right above is it also very soft and it’s most definitely a roof leak.”source ↗
“I rent and let my landlord know but sadly won’t be able to get anyone till tm.”source ↗
“Is the apartment safe to stay in for now ?”source ↗
“I am wondering if I have to fix this urgently because I am pretty much occupied by other things thesedays.”source ↗
“I have a neighbor upstairs and over the course of several months I have noticed some bubbling on the ceiling.”source ↗
“Opened up the ceiling to find this. I captured this after the neighbor flushed the toilet. Can anyone help determine where the leak is coming from?”source ↗
“Thats probably going to all come down if the leak isnt fixed.”source ↗
“You have better things to do than fix an active leak and potentially prevent your entire ceiling from collapsing?”source ↗
Where this came up
People with this problem also raised
- 22How to temporarily waterproof a damaged roof until replacement
- 48Water keeps getting in the house during heavy rain
- 52How to tell if roof flashing is installed wrong
- 3Best sealant for a roof pipe penetration
- 7Sunroof leaking down the A-pillar after rain
- 4Why are my roof shingles lifting near the gutters?