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R-60 kraft-faced fiberglass batts were installed in our modular home when it was built in 1994. We recently remodeled two rooms and the contractor made a real mess of the insulation when installing new ceiling lights and a new bathroom exhaust fan. Batts appear to have been simply ripped up without concern for protecting them for re-use.

Some effort was made to replace batts but large gaps were left between them. Many of the batts probably can be relaid between the trusses with some care; others may have to be replaced because the facing is torn.

My questions are these.

  • Is it important to maintain the (admittedly minimal) vapor barrier afforded by the kraft facing or is it OK to relay batts that have torn facing?
  • If batts have to be replaced, do I need to get ones that are faced?
  • Might it be more cost-effective to pull all the batts in the messed up areas and have them replaced by blown fiberglass insulation? (Blown insulation at least has the advantage of making it easier to insulate around IC-rated light fixtures.)
  • Finally, how important is it to remove construction debris, such as sawdust, scraps of paper, cable jacketing, etc. on top of the batts in areas where they are still intact but hard to access?
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  • Yes, you should repair or replace the vapor barrier, depending on your climate. In most areas it's important to prevent moisture due to human activity from reaching the frost front inside the insulation, where it will condense and cause mold or damage.
  • Yes, you should use faced batts as replacements, unless you intend to install poly sheeting over those cavities instead.
  • Yes, it may make sense to simply blow in cellulose or fiberglass over a new vapor barrier, but we can't say with the limited information provided. (Cost questions are also generally off-topic.)
  • Minor debris is inconsequential, except where it's large or heavy enough to cause compression of the insulation medium.
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  • Isherwood, thanks for the advice, especially about the light weight debris. I should have noted that our house is in northern Virginia: hot and humid in the summer and cold in the winter. So vapor barrier certainly is called for. The kraft faced insulation in the walls was installed using the nailing flanges, but the batts in the attic were simply laid in place after the drywall was up and so provide only a partial vapor barrier at best. That's why I was wondering about how important it is to establish a good vapor barrier where the batts have been disturbed. – user13781 Apr 14 '17 at 20:57
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    Well, if your home was built 20 years ago and it hasn't been a problem as-is, it's unlikely to be a problem going forward. The fact is that homes don't have moisture barriers, but vapor retarders--mechanisms that slow the movement of moisture to the point where it doesn't accumulate. No home has a complete seal. – isherwood Apr 15 '17 at 13:08
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We decided to simply put the original insulation batts back as carefully as possible with only minimal additions. Two contractors who were here on other matters said that the few areas that aren't covered as well as they "should" be wouldn't make much difference and that the cost of fixing them would greatly exceed the cost due to heating or cooling losses. Thanks for the advice.

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