Building Airflow Standards and the Average Contractor

Im running into some common issues in NYS that seem to keep coming up, and I am looking for feedback from others.  It is often noticed in my travels that a contractor will identify a target CFM50, and then work only to achieve that goal.


BPI's thoughts are,"Get them as tight as possible, fiqure out what amount of air needs to be made up, and provide make up air for that."


Are contractors afraid of the consequences of getting a home too tight?  Mold, Poor Client Health, etc, etc..  Is this because they dont understand the simpleness of supplying make up air?  Do they feel as though it is too costly?  Is it because Government Programs usually stiff the contractor on that type of measure?  Is it laziness? After all they achieved thier goals.  Is it that we as Trainers don't emphasize the ideals enough?


I am really just looking for thoughts.  I want to eventually address the problem locally.



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I find it's usually too costly for the client and too labor intensive. Most people get an free audit because number one they can't afford an audit let alone a deep retrofit to achieve BAS or less. A lot of my clients make just enough not to qualified for Assisted HP or any other assistance. I work hard to achieve an air reduction of  50% of the difference between the actual blower door number and the BAS, at the same time keeping it affordable for the client.

Plainly put, I do what the client can comfortably afford while doing the best you can do in retrofitting their home.

Thank you for your input

Paul said it well. If you can get the home down to the range in the BAS, you have in the practical world reached an acceptable goal. Going beyond that number with a house as tight as a drum and with controlled ventilation is for the homeowners that are, shall we say, enthusiastic about the concept, or for the ones with serious health concerns.

Contractors have a very full schedule-whether they have jobs on the books or not-and it is impractical and potentially harmful to push too hard for upgrades for fear of giving a wrong impression.

Thank you for your input


Are contractors afraid of the consequences of getting a home too tight? Mold, Poor Client Health, etc, etc.. --- YES & many are still under the assumption that houses need to breathe though it is nice to see that changing as they start learning more

Is this because they don't understand the simpleness of supplying make up air? --- Sometimes and to some extent that is because they don't understand fully what is needed, when & why so they make it more complicated than needed

Do they feel as though it is too costly? --- heh, almost all the contractors are worried about the bottom line & adding additional costs that they can't justify or they think that the other way is just as good is making it a tough sell in their minds

Is it because Government Programs usually stiff the contractor on that type of measure? --- in some cases the program calls for just getting it to X, while others are so focused on ROI that adding this negatively impacts it, Fortunately though many programs are starting to make this a prerequisite and I expect to see the WX/WAP programs adopt it as I know it in the works (now if it sees the light of day...) 

Is it laziness? After all they achieved their goals. --- Maybe for some but I tend to go with the above issues

Is it that we as Trainers don't emphasize the ideals enough? --- From what I have seen & heard - many trainers are fixated on ROI, others quite simply lack the knowledge, and others are so fixated on their idea of best practices & materials that they don't cover these topics or do so properly

Thank you for your input

Hello Tim.

I fall firmly on the side of Paul and Bruce.

If I can actually get my houses down to the BAS then it's time to party. After reaching the BAS, the additional cost of further reductions in air leakage are just not cost effective. I introduce mechanical ventilation in all cases, so that IAQ is improved and so that further reductions can be achieved without being "too tight."

I am sure that on some cases contractors fear getting too close to or dropping below the BAS, but I know that me and my colleagues are still working like mad men to just hit that BAS.


Thank you for your input


Tim, I think it can be a lot of things. 

  1. Will there still be dinosaur draft appliances?  Then you better be cautious or you'll just be cutting holes to pass draft.
  2. How passionate is the crew?  If they're more interested in punching out at 4:30 then seeing how well they can do by the client, they are the ultimate "let's stop here" decision makers (not the owner...).  
  3. Maybe they don't even realize how important their work is.  Most haven't been to a BPI class.  Make it a challenge, offer rewards for surpassing target by X, and see how things change.
  4. Confusion at the design or specification step.  "Don't go below 100% or we'll have to go back and recommend mechanical ventilation..." becomes a non-issue if you ALWAYS recommend mechanical ventilation up front, right?  (And why WOULDN'T you always recommend it?  Did you test IAQ?  I've found some loose houses have much crappier IAQ than some tight houses, so assuming IAQ and BAS  are correlated is a faulty assumption.)
  5. Confusion about the standard.  Go below 100% requires "recommend", not "must install".   (I've seen below 70% very seldom, and it's never been a big deal because you are likely to know in advance that you might get there.)  

This list could go on and on.  A lot of these issues are very subtle.  We always set a conservative target and hope to exceed it.  Under-promise and over-deliver tends to keep people happy.  

And happy people don't fill your uncompensated time with complaints. 

This is something I have been battling for awhile now. For me it is hard to explain the building airflow standard to clients without them becoming concerned about too tight of a home. It is important to explain that the standard is not necessarily an efficiency guideline but an air quality issue, but that can deter home owners as well. I have also found homes that test-in at or below the point where BPI requires mechanical ventilation, despite my best efforts these clients rarely want to tighten their homes up more. Recently, I tested a home that had poorly installed fiberglass in the rim joist, 4 inches of loose fill cellulose in the attic, about 20 recessed lights, and some open wall cavities to the attic. We knew that the home could be drastically improved upon, yet it was right at the 70% standard where mechanical ventilation is required. I often question the standard itself and how it was developed, does anyone have a resource they could guide me toward?



Eric, I have one question for you in regard to the house you spoke of that came in at 70% of the BAS. Had it been built recently by a builder with experience in higher performing homes? I just can't believe that such a house would be even close to the BAS.

I have had no problem with HOs and building tightness. I provide a report with info about the BAS that is specific to their house. I tell that that comfort, energy effociency and IAQ can be improved by targeting leakage rates at or below the BAS. I know this is not the entire story, but it gets them to the right conclusions about why to air seal their houses. I once was a crusader for fully educating HOs, but now I see myself as more of an advocate for higher performing buildings who goes out there and wins over HOs to my cause through simple education and a willingness to hold peoples hands when necessary. I have found that this approach is particularly helpful when discussing building tightness and IAQ with HOs. Just my take on it.


Thanks Patrick, the home I was speaking of was built in 1993, I don't know anything about the builder but he certainly did something right that beyond what our 3 hour assessment could see. We have also recently tested all our our blower door equipment to ensure it is giving us true numbers still, so that shouldn't be the issue. When you say that you provide a report with info. about the BAS that is specific to their house, what exactly are you providing them if you don't mind me asking? Volume, occupants, rooms, home age etc..?



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