[Greenbuilding] Insulating walls in (old) wood framed house without vapor barrier?

[Reuben Deumling]

I could imagine that a vapor barrier would be beneficial, though I skipped
it on my stick framed 1894 house. I am assuming that we are dealing with
horizontal board siding, and that the folks he is listening to are saying
/only insulate old walls if you also add a vapor barrier/
My curiosity is whether by leaving off the vapor barrier, going with what
you have, one would in fact be risking certain material deterioration?
Wouldn't the insulation material play a role? Dense pack cellulose vs
fiberglass batts?

On Monday, November 25, 2019, Mike O'Brien <obrien at hevanet.com> wrote:

> Hi, Reuben—
>
> It would make sense to install vapor retarders and air barriers to keep
> moisture out of the walls, where it will condense during winter. Are the
> local guys saying that can’t be done? Or even if it could they still would
> not insulate the walls?
>
> Usually our old frame buildings have shingles or board siding over
> shiplap, not plywood or OSB, so in our climate a wall can transfer moisture
> to the outside. Are these walls different?
>
> Best, Mike
> Sent from my iPhone
>
> On Nov 25, 2019, at 8:06 PM, Reuben Deumling <9watts at gmail.com> wrote:
>
> I realize this list has gone silent, but in the hope that some of you
> smart greenbuilding folks are still out there, receiving this email, I
> would like to pick your brains. A correspondent from Illinois has been
> cautioned by five(!) "very experienced people' not to insulate the walls in
> an old house:
>
> In the attic, yes. We are not going to put it in the walls. After talking
> to multiple old house restorers who have been in the trade 40 years or
> more, they all say one thing, that due to lack of a vapor barrier, it will
> trap moisture and rot the framing in the walls. They did a lot of
> insulating in the 1970's, and then a great deal of structural repairs in
> the 1990's on those houses.
>
> I suggested he try to find a second opinion. Please share your wisdom.
>
> Thanks very much
> Reuben Deumling (who joined this list almost twenty(!) years ago.)
>
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