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

[Stephen Collette]

Hello Reuben and all,

I would echo other’s comments. Yes it can be done, yes it can go wrong, but details details details. When I work with heritage properties (I’m a heritage professional too) I recommend focussing on the air sealing component when insulating stick frame wall systems. I do not recommend spray foam, as the spray will migrate into the drainage plane through the gaps in the planking. I’ve seen that happen. Not pretty. So whether you are opening the walls from the inside or the outside, make sure the air sealing is awesome and the existing large lumber will handle the moisture migrating through via vapour transmission safely.

Now if it was a masonry wall system, no I wouldn’t recommend insulating as the masonry may fail, especially in big masonry walls like churches and such.

I would also add that more outsulation the better. If heritage designation isn’t an issue, I took my 100 year old house 1918 and added 6” of Rockwool exterior to the house. I keep the planking on the outside (it was holding in the dry mix concrete originally installed) added more sheathing for flatness, then Delta VentSA peel and stick vapour open weather resistant barrier and then the rock wool. Finished it off with 2x4 strapping to get the full inch thickness for warranty for the wood siding finish. If you want some photos, email  me off line.

So yes, it can be done. Do it right. It’s all about the details. That’s what defines green building in my opinion.

Cheers

Stephen

Stephen Collette
BBEC, BBNC, LEED AP, CAHP, BSS
Your Healthy House - Indoor Environmental Testing & Building Consulting
http://www.yourhealthyhouse.ca
stephen at yourhealthyhouse.ca
705.652.5159

Listen to my podcast from my website
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>
> Message: 1
> Date: Mon, 25 Nov 2019 20:03:38 -0800
> From: Reuben Deumling <9watts at gmail.com>
> To: Greenbuilding <greenbuilding at lists.bioenergylists.org>
> Subject: [Greenbuilding] Insulating walls in (old) wood framed house
> without vapor barrier?
> Message-ID:
> <CAE5fceAY_YF1=JVSWKhyU+W3M70jGjfGDHnhJfiMR_172WKvww at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> 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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