Is it normal for cold air to blow out of a cut-out hole in drywall, or should this never happen between wall cavities?
Asked by Beverly Wilson 
4 weeks ago
Last Updated: October 26, 2024
Is it normal to feel cold air blowing out of a hole cut in drywall? Some have mentioned that it’s normal to have cold air between wall cavities, but others say it shouldn’t happen. What do you think?
It really depends on where this is and when the house was constructed. Older homes didn’t have the same level of sealing as modern ones do.
Hey , it really depends on how cold it is. If it’s colder than inside but warmer than outside, it might seem normal but you could still feel a chill.
Hey , this house is brand new, only 10 months old, and we’re talking about the exterior wall here. This is the same wall where the hvac lines are installed.
It’s important to address the issue. It seems like the Vapor barrier might not be sealed properly. Using a FLIR camera both on the exterior and interior can help you narrow down where to investigate further. The next steps will depend on what you discover. Ensure the Vapor barrier is properly sealed and consider using spray foam to close any gaps that are allowing air to enter.
Is Flir a thermal imaging tool? When using it, what should I look for? Will I likely have to remove the siding from the outside of the house or cut through the drywall inside the bedroom to fix the issue? What are the consequences of not addressing it?
Typically, the plumbing and electrical penetrations may not be properly sealed. It’s not necessarily incorrect, but there is room for improvement. This also indicates that the wall may not be adequately insulated, which is common for an interior wall on a raised foundation. You could have a young person crawl underneath and use spray foam to seal the holes.
Hey , but this wall won’t let you access the holes at the top
Hey there , this wall is on the outside
That does sound concerning. We’ve been insulating homes since the 70’s. There are methods to insulate older homes, although they may not be very aesthetically pleasing.
Rarely do openings at the top bring cold air into the hole. However, with the current storm conditions, anything is possible. Typically, heat from the house rises.
I’m not sure if I agree … I’ve actually seen pipes freeze due to openings at the upper part of walls. Depending on the wind, air can easily be pushed downward. It’s a bit complicated. If exhaust fans are on, the pressure could be pushed in or down the wall. In a still situation, you’re correct, heat will rise and escape through holes at the top … but there needs to be a way for air to come in for that to happen (which is usually the case).
She didn’t specifically mention fans, but most exhaust fans typically don’t pull in enough cold air. Based on the information I had, I was trying to detect the earthy smell. I’m happy to be back in the West where frozen pipes are rare.
Pointed out these holes. On the other side of this bedroom wall in the basement are the HVAC systems.
Normal? Well it’s pretty common. In terms of modern construction… it really shouldn’t happen (that’s the idea)… What’s happening is that cold air is sneaking into the wall cavity through holes from things like plumbing, electrical, etc. in the top plate of the wall (or the bottom plate/floor). In modern construction, all holes that go through the framing are sealed to prevent these leaks. This leads to excessive heat loss/gain due to air leakage. That cold air can enter through wall outlets and it just ends up chilling the wall when it shouldn’t. It seems like you might have some air leakage… Do you have insulation in the attic? What type(s)? What about the floor? Is it a crawlspace? Vented? Basement? Heated? There are plenty of places where cold air leaks can stem from… so it’s a good idea to investigate your house’s construction a bit. How old is your house? Is attic access easy? There’s a lot to discover and understand… once you do that, you can start forming a plan to reduce or eliminate the leaks.
Just finished building this new wall in the basement bedroom. It’s on the outside of the house and the same wall where the hvac lines are located. We have three units. Whenever the AC is running in the summer, it makes a buzzing noise the entire time. Once I turn it off, the noise disappears. The HVAC installer keeps saying the sound is normal… but many visitors have listened and agreed that it’s not normal. They say it’s the air compressor sound, but why is it so loud inside the room? The finished walk-out basement is built on a slab.
So let’s simplify this. When you mention HVAC lines, are you referring to the refrigerant lines connected to the outdoor cooling unit? It seems like they weren’t properly sealed when they were installed through the wall or floor, usually at the floor joist level. This should have been taken care of during the construction phase. Take a look outside, do the lines appear sealed where they enter the house? (not a definite confirmation). Also, check the electrical conduit… anything that goes through the wall should be sealed. That might be the only issue. It sounds like there’s a lot of noise coming through the lines too. Was the wall properly insulated or was drywall just put up to finish the basement? Is your mechanical room next to the bedroom?
I find it amusing when contractors say it’s ‘normal’, haha! Maybe it’s normal for their line of work…
He’s the one who is talking about this wall. When you look at it from the outside, you can see how the HVAC lines are connected. There is some spray foam and some areas where it seems like there is clear glue or caulk. There might be a small hole somewhere, but I can’t figure out how it would be causing so much cold air to come through on the other side of the wall. The builder mentioned that there might be an unsealed area in the zip system. Do they need to remove the siding to check for this?
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What are the consequences of simply covering up the hole without fixing the cold air issue? Some say it’s common, while others insist it’s unacceptable.
One concern is heat escaping. Could there also be a problem with bugs? It’s hard to tell from the picture. Could it be a bad seal? Uncertain.
It’s not ideal. And it’s not the outcome I aim for when constructing something. However, it’s not really out of the ordinary either
What do you think would happen if we don’t locate where the cold air is coming from in the wall cavity? If we never made those holes, we wouldn’t have discovered it in the first place.
There are many houses similar to this one. You basically have two options: either ignore it and deal with the high utility bills, or put in the effort and money to seal it up as best as you can. Old houses are tricky to fully seal and insulate, but every little improvement helps. It’s like wearing an old coat that’s falling apart. Most of the time it’s fine, but when it gets really cold or windy, it’s barely enough. So you add gloves, a hat, maybe a sweatshirt, etc. It won’t ever be super warm, but you can make it more tolerable. Seal up your attic, rim joist, add gaskets to switches and outlets, get new windows, weatherstrip doors, insulate walls and attic, foundation, etc.
Maybe it’s a stud cavity being used for cold air return. Do you see a vent at the top or does it seem to be coming from upstairs?
There are no vents on this wall. Cold air is coming through all the holes, which is where the HVAC lines run up. The HVAC units are on the other side of this wall. We hear a loud buzzing whenever the AC turns on in the summer, but it stops as soon as we turn the AC off. The HVAC company that installed it keeps saying the sound is normal, but everyone else disagrees.
Do you know if there is insulation in the walls? I can’t hear my AC running, even though we got it installed last summer along with a brand new HVAC system.
There is insulation present, but I’m not sure if it’s sufficient 🤷🏻♀️
You should consider getting an infrared thermometer gun to test it out.
Hey , do you have a favorite brand in mind? And what should I keep an eye out for?
If you’re worried, try this: Turn on the fan for your central a/c or heater. Then, double-check that all windows and exterior doors are shut. Grab a 3-foot piece of toilet paper. Head to any exterior door. Crack the door open about half an inch. Now, hold the toilet paper near the crack. If it stays still, you’re good. But if it starts flapping around, you might have a problem.
If I’m worried about cold air coming in from between the wall cavities, what would opening an exterior door 1/2 inch reveal?
It can help identify any air leaks in the air conditioner ducts in your attic, which could be causing the airflow issues you’re noticing.
Got it! So, should I be standing with the paper 1/2 inch away from the crack on the inside or the outside of the house? Also, can I do this with the heat on, or does it need to be actively running warm air through the supply vents?
You could try standing inside and then outside to see if you notice any airflow in either direction. And yes, the fan should be running in either heat or AC mode, or just the fan-only mode.
It’s not supposed to, but is the house brand new? Have any exterior finishes or mechanical elements been modified or maintained?
Check out this fresh house with the green zip system.
Is it vinyl siding? If it is, it might be worth unzipping a couple of rows to check if the house wrap was properly sealed at the floor level and that the necessary gasket at the wall was installed. A draft could be caused by many different factors.
Raised a question about whether the siding needs to be removed to locate the unsealed area. Alternatively, could they access it by removing the drywall from inside? What are the consequences if we choose to leave it as is? Some say that having cold air in the wall cavity is normal. Any thoughts?
Mentioned that it’s difficult to check the house wrap since it’s not vinyl siding. She suggested waiting until the siding needs replacement to assess it. The wall tends to get colder towards the outside, which is expected.
The builder, mentioned that he is arranging for someone to inspect the zip system in an area that wasn’t properly sealed. I just want to ensure that any issues are addressed, even if it means fixing them. The house is still under warranty, after all.
I can understand your frustration. It’s a good idea to be present during the inspection, and it’s helpful to have someone knowledgeable with you. It’s important to ensure everything is thoroughly checked.
Some companies offer the service of installing a fan in your doorway to circulate air in and out of your house. They might use smoke to detect where air is leaking. Another option is to hire a home inspector. And if you have a 1-year warranty, make sure to notify the builder about the issue that needs attention.
Is it an exterior wall or interior wall?
If it’s an exterior wall, it could mean that there’s insufficient insulation, a poorly sealed house wrap seam, etc.
Interior walls can feel extremely cold if they’re close to plumbing and the plates were drilled through without proper insulation around the openings. You might be getting cold air from the attic or crawl space.
‘ house has the green zip system on the exterior walls instead of house wrap. Do they need to remove the siding to locate where they didn’t seal the zipsystem/housewrap, or is there another method to find the unsealed area?
Oh wow, that zipwall is said to be top-notch. I’m not entirely sure about it, to be honest. But to access the zipwall, the siding would have to be removed. A home inspector might have more information about it.
Usually this is not considered normal.
Can you tell if there’s a top board covering the cavity or if it’s open to the attic?
Hey , are you referring to the space inside the cut out?