Discolored insulation

[Aaron Scheuerer]

Insulation in the basement ceiling is Discolored but only this one strip. Is this from water damage or something else ? Also there are vents that run through the ceiling of the basement with rust at every joint. The entire ceiling isn't insulated. Should I recommend insulating them? I'm assuming the rust is from condensation from the vents running through an unheated area.

[Jim Luttrall]

Insulation in the basement ceiling is Discolored but only this one strip. Is this from water damage or something else ? Also there are vents that run through the ceiling of the basement with rust at every joint. The entire ceiling isn't insulated. Should I recommend insulating them? I'm assuming the rust is from condensation from the vents running through an unheated area.

The discoloration likely is from air flow with the discoloration being dust as the insulation acts like a big air filter. Column effect will cause warm air to rise at all openings and Ill bet there is a wet wall for building sewer/mechanicals that is open to the upper floors. Not enough information to guess about the rust on the vents.

[Aaron Scheuerer]

The discoloration likely is from air flow with the discoloration being dust as the insulation acts like a big air filter. Column effect will cause warm air to rise at all openings and Ill bet there is a wet wall for building sewer/mechanicals that is open to the upper floors. Not enough information to guess about the rust on the vents.


Thank you you very much

[Grant Medich]

While the photo does a good job of explaining the color difference, it falls short of allowing one to give you a direct answer.

I have seen drastic color differences within a single roll of insulation which was created during the manufacturing process. I have seen drastic color differences between rolls purchased at the same time.

I have also seen rolls used long after they had been purchased, installed alongside newly purchased rolls. I have also seen sound-attenuating batts reclaimed from commercial demolitions where the recycler intended to use them at home. This last example can result in a very wide spectrum of color.

If it were simply dust infiltration, you could probably shake or tap some of it to produce visible results. Dormant biologic growth would not fall off so easily.

Regarding the partial installation, I usually advocate an "insulate or don't insulate" approach. If the insulation actually creates a temperature differential, that differential can concentrate its interaction wherever insulation is absent. This can "drive" the warm/cold air effect to this area.

This being said, your photo seems to show insulation used as sound attenuation. The steel studs seen at the right indicate the possibility that the owner intended to finish the basement. Sound attenuation would reduce floor/ceiling noise transmission while improving HVAC zone control. The non-insulated round ducts indicate the basement was not being relegated to serving simply as a cold, unconditioned mechanical space.

Mentioning the ducts, any rust on them due to condensation would have more to do with humidity control than anything else. Cold ducts conducting A/C conditioned air can develop exterior condensation when basement humidity is not properly managed.

[Aaron Scheuerer]

While the photo does a good job of explaining the color difference, it falls short of allowing one to give you a direct answer.

I have seen drastic color differences within a single roll of insulation which was created during the manufacturing process. I have seen drastic color differences between rolls purchased at the same time.

I have also seen rolls used long after they had been purchased, installed alongside newly purchased rolls. I have also seen sound-attenuating batts reclaimed from commercial demolitions where the recycler intended to use them at home. This last example can result in a very wide spectrum of color.

If it were simply dust infiltration, you could probably shake or tap some of it to produce visible results. Dormant biologic growth would not fall off so easily.

Regarding the partial installation, I usually advocate an "insulate or don't insulate" approach. If the insulation actually creates a temperature differential, that differential can concentrate its interaction wherever insulation is absent. This can "drive" the warm/cold air effect to this area.

This being said, your photo seems to show insulation used as sound attenuation. The steel studs seen at the right indicate the possibility that the owner intended to finish the basement. Sound attenuation would reduce floor/ceiling noise transmission while improving HVAC zone control. The non-insulated round ducts indicate the basement was not being relegated to serving simply as a cold, unconditioned mechanical space.

Mentioning the ducts, any rust on them due to condensation would have more to do with humidity control than anything else. Cold ducts conducting A/C conditioned air can develop exterior condensation when basement humidity is not properly managed.


Wow! Thanks man this is really informative!!!!!

[Jerry Peck]

Mentioning the ducts, any rust on them due to condensation would have more to do with humidity control than anything else. Cold ducts conducting A/C conditioned air can develop exterior condensation when basement humidity is not properly managed.

Those metal ducts may be insulated on their interior.

The metal ducts should have taped and mastic sealed joints (required and enforced in commercial work, less likely to be enforced in residential work).

The insulation may have, if inside the metal ducts, come loose from the metal ducts, which allows the cold air to reach the metal ducts, and, as described above, could created condensation issues, inside the ducts as well as outside the ducts, and rusting could be from moisture being forced out of the duct joints at points of leakage.

Metal ducts in a basement (which would be unconditioned space) would need to be insulated (which does not mean they were insulated ducts, just that they are required to be insulated).

[Grant Medich]

Those metal ducts may be insulated on their interior.
I was thinking more about the round ducts shown, Jerry. Have you ever encountered interior insulation on round ducting? I have not, so don't know if it is even available.

[Jerry Peck]

I was thinking more about the round ducts shown, Jerry. Have you ever encountered interior insulation on round ducting? I have not, so don't know if it is even available.

Grant,

I've only seen rectangular metal ducts insulated on the interior.

That round metal elbow looks added on, but the connection of the rectangular plenum stuck up into the rectangular duct doesn't look professionally done either.

If it isn't conditioned space then the ducts should be (are required to be) insulated ... ducts in conditioned space 'should' also be insulated (but are not "required" to be).

[Aaron Scheuerer]

yea the potential buyer told me that the basement was in the process of being finished by the home owner but they shut him down because he didn't get any permits. There wasn't a fire stop on top of any the studded walls either you could tell whoever did it wasn't qualified.

[Grant Medich]

If it isn't conditioned space then the ducts should be (are required to be) insulated ... ducts in conditioned space 'should' also be insulated (but are not "required" to be).
I remember back when I was studying for a green certification credential that it finally hit me that the entire purpose of a duct is to control the delivery of conditioned air. Once I realized that simple fact, insulated, sealed ducts made so much more sense to me. Leaks = loss of controlled delivery.