Re: Blown-in cellulose and mass confusion - please help me!
Now there's a blast from the past --- along with the old Eaton's and Canadaian Alladin mail order homes.
Though those U.G.G homes were more in Saskatchewan I believe since that's where U.G.G was formed ---- Indian Head if I recal correctly.
Typically for us folks on the prairies we generally would always consider a vapour barrier installed in any home.
With cellulose , fiber glass , rock wool and even 1/2 pound open cell spray foam --- building code would require an additional vapour barrier installed with any new construction or renovation in our climate .
However, in a retrofit application it is allowed and there wouldn't be any need to require a vapour barrier.
This works without the vapour barrier as long as you seal the wall as air tight as you can make it.
If you were to take down the walls then it would be best to apply a vapour barrier.
The existing walls probably have several coats of paint with some being at least 2 coats of oil based paint --- or even some layers of vinyl wall paper.
The many coats of paint ( especially the oil based ) combined with the plaster itself acts as a vapour retarder. While the walls will allow some vapour to pass through the process of diffusion, it will slow and limit the diffusion . Whereas if you were to out up 6 mil poly vapour barrier this material does not allow vapour to pass through ----- hence the difference between retarder and barrier.
The main concern is air infiltration from the indoor space into the walls that will create moisture issues --- regardless what type of insulation.
If you aren't taking down the walls and are simply going to blow in the insulation just make sure it's dense packed.
just some thoughts.
"" an ounce of perception -- a pound of obscure "