cold air return

Insulation observed under I-Joist system. This is utilized for a cold air return as sheet metal as observed under I-joists when viewed after removing air filter from return air register in hallway. I have attached picture of this viewed from basement. Mildew like substance was observed on top of visible I-joist, also viewed from return air register in hallway. This does not appear to be a proper system. Any thoughts.

I would imagine by looking at the photos that there are large areas of air leakage from the ducts.

I would recommend to my client to hire a certified energy rater.

The reasons would be that after speaking to a few certified raters they seem to find that the so called professional can not make the proper repairs.

For example you have an insulation and HVAC issue. So you would need at least 2 contractors. Is the HVAC contractor going to properly seal the ducts with mastic. Bad idea to use the I joist cavities as returns. The insulation guy what is he going to say.

Not sure if a rater would be able to come out within the contingency period. You could also refer to someone who understands building science. (I have a guy I use until I can perform the audits)

The certified rater would properly test the systems(Insulation and duct work)

It is hard to tell from the photos the thermal boundaries of the home. I would say there are definitely some issues with the insulation and duct system.

Do you have any more photos.

Hi David, I hope your energy auditor class is coming along well.

Can you explain why you believe your statement? Joist cavities (including I-joists) are used regularly around here for return air but, granted, they are more professionally installed/sealed.

The biggest concern from an energy auditors view point is when building cavities are being used for return air they are prone to excessive air leakage through the joints in the building materials.

I will see shortly. Once I take and hopefully past this test. Then I am going to get my equipment. The first house I am doing is mine.

Going to use a duct blaster, blower door and fog machine to determine my air leaks and I have returns using sub floor joists.

Then I will get some mastic and show my heating contractor the proper methods to seal the duct system.

I need to find an insulation, electrician and general contractor to perform the work once I do the audits. I can do or sub the work as long as my client signs the proper papers(Dam I need to go back and study)

So, it’s really not a bad idea to use the joist cavity so much as quality installation issue, yes?

I’ve never felt that panning floor joists or stud wall cavities for R/A raceways was ever a good idea.
The home building construction industry lobbied heavily back in the early 70’s to get approval for that type of design installation in our area, mainly for cost savings.
As for energy, health, cost considerations/savings/quality/etc., I recommend everyone who hasen’t yet, take the time to open a few of those cavities and look at the conditions encapsulated.
I find in most cases (80%+) the areas have lint, dust, moisture stains, dead insects, food, trash, etc., constituting some level of possible health issues, and that’s just after a few short years. I’ve never found one installation that I would consider remotely airtight, energy efficient, environmentally healthy, etc.
The house we live in now (built 1990), had panned floor joist for (2) central R/A floor openings. I replaced both R/A’s with sealed sheetmetal (insulated) and flex connectors/flex ducts.
I always explain an installation like this to my clients, both verbally and written in my report.