How to become an air control freak!
This post will attempt to get everyone on board with the idea of being an air control freak, and becoming one will give you one of the biggest bangs for your buck in energy savings. We obviously do not want to stop all air from coming into the home. In fact, ventilation is crucial to healthy indoor air quality.
We just want control.
On the interior of the home there are lots of ways that homeowners and home inspectors can actually see evidence of heat loss—or more accurately—air movement. While the title of the post is an attempt to convey that the science of this topic is a little more complicated than I want to get into in this post, I will simply lump all of these mechanisms into “ghosting” for simplification. For a more technical review of all of these mechanisms see: Thermal Tracking: How to Diagnose Indoor Wall or Ceiling Ghosting Stains.
Ghosting at the edges of carpet where air is coming and going in and out of the building is one such example.
Part of the reason this is complicated is because “ghosting” does not always mean heat loss or gain—it typically indicates areas of more or less air movement in relation to warmer or cooler surfaces—or just plain air movement. Ghosting where air is moving around poorly weather-stripped doors is another example.
Ghosting can give away missing insulation above a ceiling,
or even no insulation at all.
Ghosting can show where air is moving in and out of the home at an attic or crawl space access hatch—the carpet is merely filtering the air.
On the exterior of the home one can also find similar ghosting where air is moving in and out of the building.
Air always has dust particles in it and over time it will build up in these areas creating these various shadows of air movement. You can’t see the air but you can see where it moves.
Sometimes it is not dust particles that give us an indication of air movement and heat loss, as can be seen in the frost patterns on this building.
At a recent inspection I had another example of a “visual representation” of heat loss. This time it was not so much by signs of air movement, but a combination of conduction and air movement. It was a cold day and moisture had condensed all over the siding of the buildings. There were four buildings each with four apartments. The north sides of all four buildings—the north sides of all of the apartments—looked like the following picture.
The dry area under each window is where an in-wall, forced-air, electric heater is located. Every window looked like this—whether the heater was on or not. Most were not on at the time of inspection; in fact one was not even functional.
This is an example of where the energy code, as a “minimum” standard, falls a bit short of “best practice.” If the entire cavity was filled with duct it would be required to be insulated to the level of the rest of the wall, but an item like a pipe, electrical outlets or these small heaters are considered minor breaches of requirements and the walls are not required to be insulated behind the heaters—or at least not to the level of the rest of the wall.
One of the questions I frequently am asked is, why can’t these spaces be the means of bringing fresh air into the home? The simple reason—and there are more complicated reasons—is that these bypasses work 24/7—far more than is necessary if we maintain control.
What signs of air leakage can you find around your home?
By Charles Buell, Real Estate Inspections in Seattle
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Michelle Schulze says
I bought a condo where sometime in the past I the bottom floor ones, like mine, had all of the fireplaces closed off. Above the mantle area on the ceiling is where my darkest spot of thermal tracking is, although black soot now coats everything in my home. My questions are what type of company do I contact to check it out and would you know if I might have a case against the association for not having the work properly done? Almost everything in my one year old home is ruined. Carpet, furniture, paint….
Charles Buell says
Sounds to me like there might be something else going on. You will want to contact a building performance professional. You may have to consult an industrial hygienist to sort it out. Providing pictures might help me make more useful comments.
shannon says
Hi there. We returned from holiday to find this brown stain on our daughters bedroom ceiling. We have gone into the attic frequently during heavy rains in the past few weeks and found no evidence of a roof leak. The stain has not changed and is dry to the touch. There are no pipes above her room. Could this be Thermal Tracking?
Charles Buell says
That stain is more consistent with some sort of leaking—I would contact a qualified home inspector that does thermal imaging and uses moisture meters.
Marilyn says
Hi there
I’ve been reading your blog. I am about to paint three rooms in my house that I have. It painted myself since we moved in 9 years ago. For sure I had thermal tracking on our vaulted ceiling in the family room. Three rooms all on the same side of the house (opposite side from family room location) have dirt marks on the ceiling corners. Do we have bad or missing insulation? These rooms would be outdoor except we have an in law built over the garage, so that is what is on the other side of the walls.
Charles Buell says
I can’t tell you for sure that you have “missing” insulation but those areas are for some reason “colder.” Air may be getting under the insulation, it may be missing, or it may be where framing is the poor insulation. Someone would have to get in the area above these locations to know for sure or if access was not possible, more invasive investigation might be necessary.
tim says
HI, is this thermal tracking? It is all over the house, the studs are metal. If it is how do i if it?
Do i have to remove the sheetrock and put foam board over the metal studs then put sheetrock back up?
Charles Buell says
Do you burn candles or wood? How recently has the wall been painted?
Tim says
Hi it is a house i am considering buying. the home owner said they only painted house once in 2002 when built. I do not know about the candles, there is a ventless gas logs in the room show. I took a contractor over today to inspect but he had never seen before. However in the car garage it has the same thing on the walls it is on every wall in garage and the exterior walls for the garage are brick from bottom to top, there is no heating/cooling system for garage.
Its in the dining room, kitchen, bedroom, everywhere.
The house is brick with stucco accents at the tops. We are in the south(North Carolina), with high humidity.
tim says
Ventless gas logs in the same room, used two months (Dec, Jan) out of the year. The main heating/cooling system is a Tran gas pack. Central air.
Charles Buell says
There would have to be a source of soot in conjunction with correct temperature differentials. The studs are cooler (ie wetter) and collecting soot. You will want to contact a building performance professional to figure out what all your causes are. Stack effect and the house near soot making industry/highways can sometimes be the source. Over 16 years I would expect to see some—whether this is “abnormal” someone with experience in your area can tell you.
tim says
Just your opinion do you think removing the sheetrock and placing a thermal break over the metal studs then reattaching the sheetrook would be a possible solution? Since the exterior walls are brick and the ceiling is vaulted with no attic space.
Charles Buell says
Sure that might work, but why not just repaint and see if that works. Your lifestyle might not recreate the cause.