I've been asked to answer a question regarding a touchie subject with some:

Q. Why does membership in IAC2 require membership in NACHI?

A: I’m asked this question often by mold inspectors who do not offer home inspections, but want to join IAC2 www.iac2.org . Here is my thinking on the matter:

  1. IAC2 doesn’t exist for the benefit of mold inspectors. It’s not to help radon inspectors either. And it’s not for environmental or IAQ professionals. IAC2 only serves NACHI members. A private trade association like IAC2 is not a government agency. It has no duty to be fair. IAC2 is for NACHI members only. I founded IAC2 to serve NACHI members only.
  2. IAC2 is technically interlinked to NACHI as a sister association. It accesses NACHI’s member database so that members making changes from www.nachi.org/profileintro.htm also change their information at IAC2. It would be difficult for us to make one a member of IAC2 without them being a member of NACHI.
  3. IAC2’s official opinion is that an 8 hour mold course only teaches one to take mold samples, but is not adequate to teach a mold inspector everything he needs to know. A mold inspector who is not a home inspector is not qualified to inspect for mold IMHO. He/she is only qualified to take mold samples. A big difference. A working knowledge of plumbing systems, drainage, water proofing, downspouts, crawl space ventillation, condensation, etc. is needed to be a good mold inspector. Industrial Hygenists have NO BUSINESS doing mold inspections! Yes, I said it.
  4. NACHI is not a home inspection organization (at least not any longer). NACHI is an inspection organization. Much of the education/exams/quizzes we offer deal directly with mold, and indirectly with the causes of it (plumbing leaks, negative drainage, stucco, etc). See #3 above. The two disciplines are intertwined.
  5. The minimum requirements for IAC2 are at least an 8 hour or 16 hour course in either mold or radon PLUS all of NACHI’s existing requirements www.nachi.org/rigorous2006.htm. If we lower the requirements for IAC2 just so an non-home inspector can get in, where would that lead? Would we allow an inspector who only works with condos skip our roofing course because roofs are common areas uninspected? Would we allow our Alaskan members to answer air conditioning questions incorrectly? There would be no end.
    *]Finally, even if a mold inspector was over qualified, lt’s say he was a Nobel Laureate on the subject of mold, I still don’t want to help him take any work away from NACHI members. I (like IAC2) am here to serve NACHI members… exclusively.
    Hope that clarifies my thinking on the subject.

Don’t understand why this is a touchie subject. They want to join IAC2 but do not want to be a member of NACHI. It sounds like IAC2 has something to offer and only the members of NACHI will benefit. I see nothing wrong with this.

I think the fault is mine. IAC2 looks very much like a totally independent indoor air quality association. It isn’t. www.iac2.org like www.MoveinCertified.com or www.InspectorPages.com or www.OverSeeIt.com or whatever… are NACHI sister operations, for NACHI members only.

Furthermore, I had the pleasure of selling a home to an IAQ PhD. I was surprised that when I took him around one turn and down the stairs (a straight string) to the basement (basements back in PA are often completely below grade with only hopper windows high on the walls) he was lost. He asked me which wall was the front of the house. Again, you cannot be a mold inspector without first being a home inspector IMHO. Residential mold investigations, inspections, and testing should be done only by qualified home inspectors (www.IAC2.org), not IAQ-only experts. You need a working understanding of homes and all that’s in them to do a proper mold inspection. IMHO. PhD’s normally don’t have what it takes.

Brutally frank, ballsy and controversial statements, Nick, but not unexpected coming from you.

If someone really takes the time to think about it, they will agree with most, if not all, of what you are saying. Basically, it’s all about knowing the 'house as a system." Just as we meet roofers who have shingled hundreds of houses, yet know nothing about attic ventilation or how it affects the life of the shingles, the same limitations exist for people who do strictly ‘mould inspections’.

Bill Mullen
Sarnia, Ontario

We also have Home inspectors that do not keep with whats happening now . I expect in the not too distant future we will no longer vent attics.


Read this one http://www.buildingscience.com/docum…bly/main_topic

and this one http://www.cmhc_schl.gc.ca/en/co/maho/gemare/gemare_001.cfm

… Cookie

That might be so, Roy. I have read the information many times. However, these new theories don’t hold water with existing houses unless much more than just not venting the attic is done. As with all house system matters, not venting the attic will never work in isolation.

I’m sure you have seen shingles very prematurely deteriorated due to poor attic ventilation.

Bill Mullen

Mold is a symptom. The disease and the house have to be looked at holistically… and that requires a home inspector. Who better?

…the knee bone’s connected to the…

Right, Nick. It does nobody any good at all just to identify the presence of mould. That’s easy. Only a well trained home inspector can add up the evidence and point to a cause or causes and recommend the right people for remediation.

How many times have we seen some ‘expert’ come in and charge big money to clean up a mould situation yet ignore (or not recognize) the causes completely, only to have the mould reappear soon after?

Bill Mullen

Thanks for sticking to your guns Nick!

I have seen shingles deteriorated many times but I did not or do not say why they are deteriorated.
I am very good home inspector but try to know my limitations on knowing why the shingles failed .
They could have been 10 year shingles or faulty shingles .
Having read many things I am not convinced that ventilation extends or shortens the life on shingles .
What I have read there is not much different in the temp of shingles in a ventilated attic and an invented attic.

I do suspect TV Ariel’s shorten the life on shingles under them .
Damp areas near a body of water grow moss especially if shielded from sun and wind by trees.

… Cookie

TV aerials don’t harm shingles at all. Normally it’s the caustic droppings from birds sitting on the aerials that cause the problems.

And yes, I have seen many examples of shingles that were deteriorated early because of poor ventilation. One thing I insisted on when I was a contractor was that the roofer had to ventilate the attic very well, both top and bottom. I have been back to many of the houses that I built over the years and the shingles on them rarely gave out for at least twenty years while others in the same subdivisions were being replaced after ten to fifteen years.

Bill Mullen

I think most good inspectors know that it is Bird poo that does the damage and most know that a zinc strip will stop the moss from growing .
I guess we will both have to do more reading to see who is correct about how ventilation does or does not help the life of shingles .
Ventilation sure does make a difference in helping to remove the moisture that gets into the attic from and incorrect sealed home .
This of course makes a huge difference to MOULD growth in the attic .
I expect the NACHI and OAHI members who took the FREE NACHI course on mould that was put on in Toronto by Pro-lab are a lot smarter on MOULD then those who did not come to it .
Of Course the$99;00 NACHI Toronto Conference had a huge amount of free courses and I am Glad to say some OAHI members took part in it .
To bad it was not better advertised to CAHPI/OAHI so they too could have had the chance to learn so much.
A BIG Thank you to NACHI and PRO-LAB for all you have done for the Canadian Home Inspectors.

… Cookie

Below copied from: http://www.casma.ca/en/bulletin_01.shtml

Although not usually recognized as a major design consideration, the proper ventilation of the attic area is an essential factor in gaining the maximum service life out of the building materials used in the roof assembly, in addition to improving heating and cooling costs. Overlooking this consideration may result in premature failure of the roofing system…

Hope this helps,


Nick, I agree with Randy, stick to your guns!

Just a little out of date original published in 1992 updated in1996

Most articles I read now disagree with this idea.

No. 1
Revision: 1996-10-16

… Cookie

An interesting article by Carson Dunlop
… Cookie


Maybe you used a better shingle than the other guys. Maybe you installed better house, not roof/attic ventilation, and vented it to the exterior and not to the attic. Maybe you built tighter ceilings that did not allow that much moisture and air leakage to the attic where it may eventually have an effect on the shingles (It has been stated by some that interior attic moisture can cause shingles to fail prematurely.)

If these homes were in the same subdivisions that were built under the jurisdiction of a building code and officials, then wouldn’t they all have at least “code ventilation” installed. Are you implying that you went beyond code requirements and that roofs with code ventilation fail?

See this thread: http://www.nachi.org/forum/showthread.php?t=19078
Look at the last page picture in the research report URL in post #78

It is being said by more and more sources that shingle quality, shingle colour, shingle orientation/direction, latitude of installation and at the end of the list maybe ventilation, are the items that affect shingle life!

I would expect nothing less from you Nick, and I agree with you.

I will add that in my experience many people want one stop shopping and therefore they tend to expect a mold inspector to write up remediation specifications, which of course we do not do. That is where the Industrial Hygenists have the edge of marketing themselves as one who can test for mold AND write up remediation specs AND follow the remediation project through to completion AND perform a clearance test upon completion.

J.B. Anderson Inspections Inc.

I have seen over 80 degrees difference in temps between a good ventilation job and a poor one, a good job definitely extends the life,(or should I say allows the shingles to last as long as they are designed) I don’t need to depend on articles to know the difference, I know houses with both good and bad ventilation, and I have seen the difference in the condition of the shingles. The difference Nick is pointing out is like with auto mechanics, there are parts replacers and there are mechanics, the mechanic finds out what caused the failure, while the replacer does not have a clue, he just puts a new part on.