Blower Door Testing. Please proof this new inspection article.

Where did the author get this data?

“A 15-foot tall building with a 50º-temperature difference between the inside and outside will have a 5-pascal pressure difference from the top of the building to the bottom.”

Also, I agree with some of the previous posts in regards to IAQ issues. The author might want to read chapter 10 of the Krigger book.


See post #7

See post #21

Some pollutants and mold are invisible or impossible to report
on during a normal home inspection. It is not even legal in
many states to report on items the require an environmental
or lab test to discern (asbestos, mold, allergens, insulation dust,
micro organism, lead dust, residue of old pesticides, etc…)

Many of these items may not be affected by outside wind most
of the time (as far entering the dwelling) A blower door sucks
INTO THE HOUSE in such a unique fashion that it cannot be
reproduced by natural wind or outdoor pressures in some

Turn on a blower door and release some smoke. Watch
the velocity as it moves. Now do it again on a windy day
and see if you can reproduce the same velocity. You

Perhaps you were never trained in IAQ issues or building
science. It might help you to study some thing’s outside
the owners manual that came with your new blower door

Survey for pollutants that may pollute the air during a
blower door test.

The problem is this… a visual survey cannot see the huge
potential and variety of pollutant issues that may be drawn
in to the dwelling. It is assumed that it will happen in such low
enough degrees that it does not matter that much. I do
not buy that premise. I have talked to too many people who
got sick or know of clients who got sick after the blower
door was run.

I have personally done in excess of 1000 blower door tests on homes in the past 3 1/2 years, and have never had anyone come back to me saying it caused IAQ issues. However, I have refused to do blower door testing on probably a couple hundred homes over the years because of IAQ issues. It all comes down to doing a survey of the home before the testing begins and good 'ol common sense. There are hundreds of thousands of homes tested each year, if someone wants to stop doing them due to possible liability issues from IAQ, then that is more homes for the rest of us to do…go for it. Thats my 2 cents worth.

Sounds like 20% had IAQ that you could see. How many
have issues that cannot be seen without samples and
lab test? How many people have health issues that
show up and they do not know were their problem came

I am not saying all homes will have IAQ issues, but it is
a concern to think about. Glad to see you are aware
of it when using the blower door method.


Don’t take that 20% number and run with it. Rodney is dealing with many low income homes through a provincially funded energy retrofit program. As with poverty level owner-occupied housing anywhere, a very much higher % of all problems show up in this socially disadvantaged group.

I did the pilot project for this program under a gov contract. I now do QC under contract at varying periods. During the pilot project, in a sample of 25, there were 2 dwellings that should have been razed and new homes built but another gov dept dealing with the issues other than energy conservation does not always have the funds to build low income housing.

This is from the 2009 ICC residential energy code. I am attending a seminar for both commercial and residential energy codes in Nov. and will bring this subject up. I tend to think this is not the problem some make it out to be.
Also, this code covers renovation as well.
I believe NH energy code now requires pre and post blower door testing whenever an existing structure’s building envelope is altered by 30% or more. This has yet to be enforced yet but will be soon.

**[FONT=Times New Roman][size=2][FONT=Times New Roman][size=2]402.4.2.1 Testing option. **[/size][/FONT][/size][/FONT][FONT=Times New Roman][size=2][FONT=Times New Roman][size=2]Building envelope tightness
and insulation installation shall be considered acceptable
when tested air leakage is less than seven air changes per
hour (ACH) when tested with a blower door at a pressure
of 50 pascals (1 psf). Testing shall occur after rough in
and after installation of penetrations of the building
envelope, including penetrations for utilities, plumbing,
electrical, ventilation and combustion appliances.
During testing:

  1. Exterior windows and doors, fireplace and stove
    doors shall be closed, but not sealed;
  2. Dampers shall be closed, but not sealed, including
    exhaust, intake, makeup air, backdraft and flue
  3. Interior doors shall be open;
  4. Exterior openings for continuous ventilation systems
    and heat recovery ventilators shall be closed
    and sealed;
  5. Heating and cooling system(s) shall be turned off;
  6. HVAC ducts shall not be sealed; and
  7. Supply and return registers shall not be sealed

Problem structures can often be pressurized vs depressurized.

At that point IR is out the window (very limited scanning ability)…literally.


Can’t be true!!!..That’s going to be hard for John to take.

Don’t worry, Brian. Bubba has never allowed truth or fact to interfere with his hyperbolic promotion of his IR certification class…a class he wrote and advertised for students within just a few months after buying his first camera.

No doubt that IR devices are good tools and I think that the variety of levels of skill makes certification a necessity. Their value in an energy audit, however, is over rated unless they are being used in parts of the country with severe differences in outdoor/indoor temps.

Everyone knows IR is not good in some environments. This is common knowledge.

I see James is climbing the ladder of wisdom, even though he has no IR training of any kind. He now says…

Their value in an energy audit, however, is over rated unless they are being used in parts of the country with severe differences in outdoor/indoor temps.

Several months ago James was saying that an IR camera only worked when the outdoor/indoor temps where exactly the same. Glad to see some progress.

I wonder if the need to turn on the AC or Heater constitutes the sever temp’s James refers to?

The application of a gas suppression system requires that the room space (including the total envelope floor void / ceiling void) are adequately sealed to contain the weight of gas within the space for the required period of time against an allowable leakage rate.

Room Integrity Testing

This got off topic a little. The basics of the article is good with out getting into the details. The gauge is a manometer and reads differenced in pressure. The house can be pressurized if there is a concern with pulling in containments. I feel it’s not as good of a test because it can push open dampers like on fans and dryers causing a slightly higher leakage rate to show. You also cant use IR effectively and almost need to rely on smoke to trace leakage. But this can helpful at times especially in duct systems.

Robert, was your IR comment above with reference to doing ex-filtration?



Most buildings are depressurized using the blower door because it is easier to see/feel the leaks!


A blower door is an excellent way to get the infiltration rate of an exisiting structure to accurately compute the HVAC load requirements.