Ok, color me confused. I'm hearing both sides. So....vapor barrier on the inside or not?

No. No VB on the inside. You already have one on the outside. When moisture gets into the wall, how is it going to dry out? Not only is it a code violation, it's a recipe for rot and IAQ issues.

Check out these articles:

Do I Need a Vapor Retarder? | GreenBuildingAdvisor.com

All About Wall Rot | GreenBuildingAdvisor.com


@ mikesolar, the first one describes the various classes of vapor retarders. In it there is also a link to a BSC paper on the subject.

To do the outside of the house 2nd floor at that would be time consuming EXPENSIVE did I mention expensive.. I know I suggested it..
I have suggested for someone else not to do just for that reason, who has 30-40 grand to toss at an insulation project, Not many people, I can Vouch for that.
Just tear drywall off , extend the inside wall by a 2x6 width, extend the window sills and take 6 inches off the ceiling drywall. Stud it up like a normal wall. Put netting up, blow in Cellulose and dry wall it. Less Painful for the wallet. Doable by any home owner with a good back and basic carpentry skills.
No need to vapor barrier it. Its under the siding already to keep the wet out.

Just thinking The R value of Cellulose is lower than Fiberglass, unless they have better Cellulose then the bag I have.
So roll in fiberglass instead of blowing in cellulose is my thought.
Other people who posted here know much more than me on insulation choices... They would know what is good bang for buck.

That works if you don't mind all the new electrical work, cable, phones, paint, trim, possibly moving the stack to stay warmer, plumbing, toilets, and anything else that is now squished by a moved wall.

The outside insulation can look like a bargain if done right, and your inside life is not disrupted.

Not disrupted aside from window details. ;)

Really IMHO it's better to go with a cellulose retrofit. It is more expensive to accomplish the same initial results though. In a retrofit you really need to build a new wall beyond the existing wall to compete with the common DER foam outsulation. We have two major obstacles and we can't tackle one without addressing the other: Air movement through penetrations and energy movement through materials.

You could have an enclosure with R-1,000,000 walls and screen for all materials aside from insulation and you could have an enclosure like a vacuum tube with no R value but it's perfectly air tight. Neither will work properly for a living space.

I'm on the quest for vacuum tube tight (for moisture management) and R 1,000,000 (because no amount of conservation is ever enough.

Let us know when you find it....lol

I won't need to let anyone know because it will start raining lotus petals and there will be universal goodwill toward man.

Then the oil/pharm/war/whateverelse institutions fail.

I'm not going to sleep tonight because I am waiting for it to come.:D

I think Your right, it may be cheaper to do the outside..
The outside insulation would be much more convenient.
Good points, especially about the fixtures toilets etc. Kitchens would have to get pulled, what big Job it's turning into. I think it would be a nightmare for living conditions, would have rent a motel or whatnot.


Renting Professional scaffolding would make less daunting.

The house has thin insulation out there now, I know they do that under Vinyl siding , I am guessing that what it has now.
So a vinyl siding job as opposed to drywall/mess house gutted and losing 6 inches of elbow space in each room, especially the bathrooms, they could take a big loss in space.
It would not work very nicely to insulate inside for my house, the toilet is tight in a corner behind the bathtub/showers back wall Same with basement with no real option short losing a fair bit of the small space they have now.
Which does not help resale at all.