I love my IR camera for detecting mosture and electrical problems but what about leaks in air ducts. See attached photo. The duct is at the top right of the photo. The possible leak is in a conditioned (interior) wall. Does this really warrant being called out? First, who knows for sure what the camera is seeing. In the case of moisture I can verify with a moisture meter. This is unconfirmed. Secondly is it worth opening up the wall to potentially find nothing or to save a few bucks on the heating bill. This is a heat only system (no a/c) so condensation is a non issue. I also verified the downstream registers had solid air flow and proper temperture reading. I’m wondering how fellow inspectors are handling this type of issue. Keep in mind this is a home inspection not an energy audit. I feel as though if I document it then someone is gonna want the wall opened up which to me sounds like a waste of time and effort.
If the leaking duct is in an interior wall (inside the building envelope) there is no heat loss, the heat is still inside the building!
The only time a leaking duct is a concern is when it is passing through unconditioned space, such as a crawlspace, the ceiling of an unheated attached garage, a bay window, or an attic etc… They need to be sealed with proper tape (aluminum foil is best) and insulated.
And air leaking to the interior walls and ceilings doesn’t cause any issues like moisture condensation across the interior?
I was here looking for a roof leak.
It turned out as an HVAC leak…
If you don’t have the equipment and testing protocol to test for leakage to the exterior, you may not want to involve your opinions in your inspection. And I am not talking Thermal Imaging here…
An air leak inside the ceiling is outside the building envelope, assuming that is an attic over the ceiling. Ductwork that causes leaks that can be seen outside are also outside the building envelope, and yes both are a concern. The OP was about an interior wall.
The attic is INSIDE the building envelope, or should be. Attics are funny because they are a space that is both inside and outside. I call for spray foam insulation on the underside of the roof decking in order to make the attic “inside”.
Much of the air leakage from ducts in interior walls and floor cavities is invariably lost. It winds up finding its way out through the exterior walls, down to the floor of the garage, through the chase to the basement, the attic, etc. Additionally, every cubic foot of air that you take from the conditioned space and lose before returning it to the living space, must be made up by air leakage in through the thermal envelope. Leaky supply ducts will depressurize the house causing air infiltration. Return ducts that leak in unconditioned areas will cause an increase in pressure within the house inducing ex-filtration.
Any way you look at it, a house with leaky ducts either sucks or blows!
One method (there are others) of confirming air leak(s) in the supply air duct is to simply turn the system off (if you feel this method is needed) . Does the pattern change now? Is there more than one leak because similar installation methods were used in other areas? Leaking ducts will have more impact than just a tiny area of missing wall insulation (unless there are unconditioned air leaks along with the void).
Safe bet would be as follows - REPORT what you OBSERVE and then recommend further evaluation by a qualified professional to do more invasive inspections and cost analysis for repairs. Making detailed comments on how to repair something, and it’s cost, before more complete inspections are done, is not always wise, if you are acting as the inspector doing a non-invasive cursory inspection.
You seem concerned about reporting issues that rise to the level of being significant and want to avoid things that are so tiny they are a non-issue. That is good thing that you have this concern. The answer is a moving target and will vary from house to house.
The comments made by the other inspectors so far seem like excellent points of education and shows the value of the InterNACHI forum.
Not where I am, attic temps can be over 40 C or less than -20 C (over 100 F or less than zero F) depending on time of year. There is vapor barrier next to the ceiling with insulation above the vapor barrier and ventilation to outside. Attic temp is generally warmer than ambient, especially in summer, but very close to ambient in winter as measured by me with thermal imaging camera. Anything outside the vapor barrier is outside the building envelope by definition.
Several points here…
1: What if the assemblies, floor, wall and ceiling assemblies, are missing a …“barrier.”
Are they outside of the envelope?
2: The word barrier is misleading.
Diffusive Vapor Barrier / Retarder.
Vapor or air.
You would utilize a perm barrier in the ceiling assembly.
I was not formally educated but mentored.
Since 1984, when I first erected a two story home, I was told by material suppliers, barriers in ceiling assemblies are not allowed. The warm side can condensate. Vapour will not pass through plastic barrier.
Question; Would the idea of the envelope be considered the drywall or floor, wall and ceiling materials?
There are two types of wall assemblies.
Single and double wall frame.
A double wall is an assembly and veneer and an air space separating them.
Now a building envelope, that includes the attic space differs from a thermal envelope.
The part of a building that is insulated.
Still no takers on the decision?
Robert, the building envelope is the part of the building that contains the conditioned air, and keeps out the air from outside. That is all.
The building code requires vapor barrier of some sort.
A building envelope is the physical separators between the conditioned and unconditioned environment of a building.
Could an attic space be conditioned?
Do the vents and soffits count as conditioners?
Is the physical structure, the deck and roofing material on the rafters or truss considered physical separators?
They include; the resistance to air, water, heat, light, and noise transfer.
I personally see the attic as part of the building envelope.
The three basic elements of a building envelope are a weather barrier, air barrier, and thermal barrier.
