Insulation, Radiant and Vapor Barriers - Face stapling batts

I have a contractor adding about 1,000 sq ft to my home. Yesterday, the insulation sub started his work. I noticed they were stapling the insulation batts to the inside of the studs (16" OC 2x4's), and insisted they face staple them instead--per common best practices and the Residential Energy Code of Alabama (and International). They guys on the job basically said, "sure, whatever, the customer is always right."

Today, the manager of the insulation company prepared and had me sign a waiver accepting responsibility for damage to the drywall from face stapling the batts. The reason given is that face stapling batts onto 2x4 studs basically puts two layers of kraft paoer vapor barrier on the face of the studs (one layer from each of the batts on either side of the sutd). These two kraft vapor barriers will supposedly trap moistere behind the drywall where it is nailed to the studs, and lead to damage of the drywall and nails, and to the tape and mud if a seam is on the stud.

I am in Northern Alabama--in case climate is a factor.

The insulation contractor said he has personally observed drywall damage by moisture caused by face stapling in several homes, although it often takes 10-15 years for it to happen. He said the local utility company (TVA) no longer recommends face stapling for this reason. The whole attitude was that guys behind desks do not understand how things are in the field, so they do not care about this issue.

So, what's the story? Am I doomed? What is the best way to do this?

Or, from another angle, is there something that can be done prevents this condensation between face stapled kraft paper, or is this contractor doing something else wrong that makes his face-stapling trap moisture?

That's the first time I've heard that. How can it the batt flanges be any different from a solid piece of poly used as a vapor barrier? If the batt is stapled to the side of the stud, the stud gets no vapor barrier protection and there is an open seam to the outside wall. I think the guy was blowing smoke.

I always face staple kraft faced insulation. If you staple to the side of the studs, the insulation is compressed along the side of the stud and you don't get the full insulation value.

The install instructions on kraft faced batts say that either method is acceptable.

I would e-mail the insulation manufacturer and get their take on what this guy is telling you.

Wayne,

The installer said he has observed several cases in which moisture was trapped BETWEEN the two layers of kraft paper. When face stapling, there is a layer from each side of the stud stapled to the stud face, right? He said this is two layers of vapor barrier and that causes trapped moisture on between them which ultimately gets to the drywall and causes the tape to loosen, etc.

He said Tennesse Valley Authority no longer recommends face stapling for this reason.

I can see no motivation for him to want to side staple, unless this is true. Althought his guys and my General Contractor did say the drywall subs HATE face stapling since it makes it difficult to slide the drywall on the wall without tearing the kraft paper. Maybe that is the motivation?

He seemed very confident and experienced. I did not percieve it as a case of, "this is how we have always done it..." I'll send a note to Knauf and see how long they take to reply.

We always staple it inside the studs. I dont care how good you are and try to do a good job . You end up with bumps in the dry wall. Also you dont get a good seal for the V/B. AS I said we staple the paper inside the stud then come over that with one full sheet of 4 mil poly to cover the whole wall and seal it for a good V/B. If you look at add's for lowes and home depot they both show it stapled inside the studs also

James - No way would I believe the installer based on what "he has observed". I would want some sort of documented proof of what he's saying. I'm not saying that he's wrong, it might have to do with your location. I expect that in Northern Alabama, insulation keeps the cold (AC) in more than the cold out (makes you wonder which way the vapor barrier should face) for most of the year.
I'm just saying there is a ton of urban legend type BS out there. I wonder how he had the opportunity to measure moisture trapped between batt flanges? Consider the possibility that you pissed him off a bit by insisting that the batts be face stapled and this is just his way of getting a little payback.
This sort of thing always tweaks my curiosity. IIWM I would be writing e-mails to the insulation maker and the insurance company he cited.

Ed- I've face stapled batt flanges in 5 rooms in my house and I just finished the same in my garage and workshop. None of my walls have bumps caused by the insulation.The double thickness of the flanges is less than 1/16" and is evenly distributed on all the studs. How could this possibly cause "bumps" in the drywall?

Kraft paper in no way is a vapor barrier! I would not worry!