The ducts and the I-joists are larger than your guess.
The picture shows a violation of the manuf. specs for 2x dia between holes.
If that is the case, lets’ solve the mystery and how big are the ventilation ducts and what size are the floor joist.??
Marcel 
The ducts were adequate for the application. 
The I-joists were adequate for the span.
The diameter of the holes were more than one-half of the distance between the holes.
If I give you anymore information I will have to bill you :mrgreen:
It is starting to sound like you inspected this house too so why don’t you tell us what you measured?
This reminds me of something I once said about inspection pictures…
Pictures of inspection issues are worth a thousand subjective words.
Nothing beats being there in person and being able to reason through the issue and report it using simple words for your client.
I strongly believe also,that they have been field modified.These holes remind me of plywood being lined up on a roof,without being staggered.It definitely looks like a weak point where the holes have been notched.
Bruce;
No offense on this subject, but relative to it is the fact that we can not make judgment accurately base on a small picture. This is one where I have said before that the picture does not show the whole picture.
I have installed many I-joist in my days and still am, and Manufactures Specifications are always at hand. I have exceeded the Manufactures recommendation many times and worked with them.
In this case you find a concern and should be recorded as such and left at that.
Put it out in the field for everyone’s opinion, and guess what, we all have one of those. No end to it. We may learn a few things out of it or someone will, but it does not answer your question other than promoting discussion on the topic.
How I concluded my last post assessment, involves actual field experience with the product and guessing on the floor member size as to what it should be and actually scaling the picture on the screen proportionately to something else.
I believe that saying things like joist are of adequate size and ventilation duct is adequate might someday get you in trouble, so I would not hesitate to change that and note what you see that is existing, period. You are not a Structural Engineer that I know of.
If you tell me what the actual dimensions are or were, than maybe I can elaborate some more, and hope you do not charge me, ha. ha.
It might mean that you have to go back and ask permission to measure a few things. I will stay away from this one. Enough said.
Marcel:)
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I am entering into this late and no I did not read all the posts.
Robert is the only one here quailfied to give an expert opinion.
So here is my humble opinion.
http://www.trusjoist.com/EngSite/literature/?SubCategoryID=73&CategoryID=3
Heck, I can meet that expert opinion status. Do you need calculations in writing to be a believer?? That could be possible, but I am not cheap. ha. ha. Etymology: Middle English, from Anglo-French, from Latin opinion-, opinio, from opinari1 a : a view, judgment, or appraisal formed in the mind about a particular matter b : APPROVAL, ESTEEM Main Entry: 1ex·pert Pronunciation: 'ek-"sp&rt, ik-'Function: adjectiveEtymology: Middle English, from Anglo-French & Latin; Anglo-French, from Latin expertus, from past participle of experiri1 obsolete : EXPERIENCED2 : having, involving, or displaying special skill or knowledge derived from training or experiencesynonym see PROFICIENT Marcel
While I know many of you are experts my point was that the ‘states’ tell us who the experts are!
Hey Mike;
I could not find much that would indicate the the State Rulings define who is an expert opinion. This is all I could find. I guess it would come back to what I said, that everyone had one. But legally, you have to be one of these, I think.!
Since Epert Opinions can not be defined by the Legal Dictionary, I must waive it and stick to the proceeding two.
expert testimony
n. opinions stated during trial or deposition (testimony under oath before trial) by a specialist qualified as an expert on a subject relevant to a lawsuit or a criminal case.
expert witness
n. a person who is a specialist in a subject, often technical, who may present his/her expert opinion without having been a witness to any occurrence relating to the lawsuit or criminal case. It is an exception to the rule against giving an opinion in trial, provided that the expert is qualified by evidence of his/her expertise, training and special knowledge. If the expertise is challenged, the attorney for the party calling the “expert” must make a showing of the necessary background through questions in court, and the trial judge has discretion to qualify the witness or rule he/she is not an expert, or is an expert on limited subjects. Experts are usually paid handsomely for their services and may be asked by the opposition the amount they are receiving for their work on the case. In most jurisdictions, both sides must exchange the names and addresses of proposed experts to allow pre-trial depositions.
Marcel
Thanks, but I would also need to take field measurements and run a few calcs to formulate a professional/expert opinion. In addition to checking manufacturer’s specifications, that would include calculating the bending and shear stresses to compare to allowable stresses. There are cases where you can exceed the manufacturer’s guidelines and still have a completely acceptable installation (called an “alternate design” under typical model building codes).
However, I know where you were going with that, in that state laws typically only allow licensed professionals to make calls on things like the structural capacity of floor framing members.
JMO & 2-nickels … 
I am not so sure the I-Joist were adequate for the span since they appeared to be “springy” … which it should not be if correctly sized and installed. Although sizing is the first think that may come to mind, that could be a result of an inadequate attachment of the sub-floor sheathing to I-Joist top flange. An important consideration that installers sometimes underestimate/overlook. Oversized holes relate to shear capacity, and not directly to bending capacity which affects how stiff the I-Joists are.
What were the measured joist depths, hole sizes, and clearances?
Hi. Robert, hope you are doing fine.
I asked the same thing previously.
Marcel 
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As reported from the person who inspected the framing
Robert;
A long time ago, an Engineer once told, me after expressing my concerns about springy and bouncy floors constructed with bar joist, that I should get concerned when the floor does not bounce anymore. Somewhat true of a bridge, isn’t it.
Marcel
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I was thought it says on I joist no hole within 2 inches of the top or bottom and not to exceed more than 1/3 the size of the joist in diameter. and no cuts in the top or bottom ever.
Lawrence;
I think what you are saying applies more to stick built floor joist and not Engineered floor joist. The design is different and allows a wider range of possibilities that differ to the common wood joist.
Marcel
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For some structures you do want flexibility, but not for house framing. Flexibility of house framing (or a springy or bouncy feeling when you jump on a floor) is a classic sign of undersized framing or incorrect composite joist installation.
Amazing that in over 40 years I have yet come across a bouncy floor or springy ,because it was never subjected to the force of 350 pounds of impact.
Let’s see; K= Mv2
Figure that one out. No wonder it bounces.
Marcel 
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Just about every time I have come across a very flexible floor (i.e. very “bouncy”) there have been issues.
Like what?
Springy and bouncy are a little different in their prognosis.
Marcel
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