Cold air intrusion detection

Did a 12 month buider’s warranty inspection in a western suburb. Found this on en exterior wall corner of the 2nd floor.

This area is part of the side roof (see the house picture) and rim joist corner not sealed. The pictures are of the northwest corner of the 2nd floor southwest bedroom (the house is facing west). The last picture is of the ceiling (northwest corner) of the excersize room below.

I pointed it out to the client and they said, “So that’s why this room is so cold and we saw ice forming on the wall last winter.”

Just one more thing to check.

Hope this helps;




Sorry. Here is the last picture.



Were you using a blower door at the time or otherwise depressurizing the building?

I see things like that fairly often from just running all the fans that exhaust out. For all the hype about tight houses, very few are around here.

No. The temp differential between the outside and inside was 15 degrees (62 outside and 77 inside. The owner’s wifes father lived with them and he was older and like the heat).

If you will notice, from the full house picture (# 1). at this area there was a small roof area. The front of the house alsofaced west, and that was the direction of the prevailing wind (and it was really flat out there, for miles).

I can provide you with many other pictures of cold air intrusion without any negative pressure induced. Just cold air.

Hope this helps;

My concern is that you may be missing some of the air leakage because it is not happening at the time or place or in the direction you are looking.

When the wind is blowing cold air is pulled in the upwind side and warm air is pulled out the lee side. With little or no wind, cold air is pulled in the lower floors and warm air pulled out the upper floors. This is a gross simplification of a complex, dynamic relationship. When HVAC or fans come on, when doors close/open, when temperatures in the building change, all this can change. The attached shows direct air leakage that was only evident when the furnace came on and was looking for make up air!

So my concern is that there may be other air leakage sites that were missed because they were not “sucking” cold air when you were there at that point.

One reason I like to depressurize (using a blower door, box fan, household exhaust fans, or the HVAC system) is to equillibrate the pressure differences and be able to see ALL air leakage as infiltration at one time. It adds to the complexity of the inspection but it makes my life easier and the data more accurate.

I don’t mean to seem to lecture! These are just things I’ve learned, some the hard way, in the 25 years I’ve been looking at houses with infrared cameras.

Thermally yours,

John Snell
ASNT NDT Thermal/Infrared Level III #48166
Snell Infrared

Air leakage.jpg

All good points.

I start the clothes dryer (air fluff), all bathroom exhaust fans and the stove vent hood (if it exhaust to the exterior) before I scan. I have rarely found it necessary to use a blower door (but I will if they don’t have these).

I do not try to do a rigorious, quantitative test (and defer to a better guy, if needed) as part of a home inspection. Generalists, not specialists.

I do take into account the wind speed, direction and all that.

In this particular case (this was just a case study, for iNACHI board education) the clients were complaining that this particular bedroom (their 9 year old daughter’s room) was always cold.

I was addressing, and trying to answer, their particular concern, not quantitativly test their entire house.

Besides, this was the only room that had that wooden trim around the rim joist area. Given the usual constuction techniques particular to this area, I knew that most of these types of houses had this problem (improper or not taping of the Tyvek.

On most Sundays, I cruise the new developments and check out what the contractors are doing (or not doing). In this way, I can learn the latest scams and defects.

This was just part of a regular warranty inspection and I did not want to have to charge the client for a full blown pressure test.

Hope this helps;

Tip: If you have a gas furnace located in an un-conditioned space, remove the two screws on the a/c coil cover and crack the cover or remove it.

This didn’t show till I did.