Thread: Multiple vapor barriers

Attic today had three inches of blown-in insulation without a vapor barrier.

Then someone added six inches of fiberglass rolls with a foil faced barrier facing the unheated area.

Another six inches of rolled fiberglass was then laid over that with the kraft faced vapor barrier facing the foil faced barrier.

This is an investment property, an apartment building for students at a local university.

Is it really worth having all the insulation removed, a proper vapor barrier installed and then putting the insulation in correctly (with one of the layers having the vapor barrier removed)?

Jeff Beck
Foresight Inspection

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I think you would have to evaluate the attic area. Is there any moisture problem visible? Is there any moisture trapped in the first layer of insulation that could damage it? do either layers of vapor barrier actually seal off an area or are they just laid next to each other? How do the energy bills stack up? These are things I would weigh in addition to the cost of pulling it up and doing it right.
I do prefer to have it done right, so I may error on behalf of redoing it if it was my investment. I think you should call it out and say what you see and let the investor make up his/her mind on what they want for their dollar.
Rick

I have heard you can slice the vapor barrier with a knife instead of replacement. Anyone heard of this as workable solution?

The best solution is to just pull off the vapor barriers.

Once you start stacking vapor barriers, you can start causing moisture to collect between the vapor barriers. The description could have moisture collecting within the insulation between the ceiling and the first vapor barrier, and within the insulation between each additional vapor barrier.

I have to agree with Jerry on this. I've seen it as a common problem. People don't understand how the products work together.
Ripping it all out sounds like overkill. Depending on overall ventilation in the space and insulation compaction it may or may not be a problem.
Sounds like a good opportunity for additional revenue.
- check existing moisture levels, monitor for the next 30,60 days with repeat insp during different weather patterns, etc.
- give report on acceptable levels (by manuf. standards) etc. and current levels etc.
Read 'consulting'

Let's see, remove the vapor barriers - cost maybe $500 depending on the size and labor cost in your area.
Or, "monitor" for the rest of the life of the structure at let's say $100 per visit at each change of season for the 30 year mortage for a total of $12,000.

I think I would tell my client to have it fixed, rather than "monitor" no matter the possible additional income stream. JMHO

Slicing the vapor barrier will not be that effective. When the insulation is put in place the slice will almost completely close up.