Cellulose Retro Fit Plaster Walls -Good or Bad Idea?
I live in Toronto, Ontario, Canada and I own an older home built in 1912. As many of you likely know, back a century ago the majority of these homes were built without insulation and the walls simply consisted of brick and plaster. My home isn’t much different. It is a brick home, with a 2 x 4 structure, that has open/empty stud bay cavities that are 16″ apart (give or take), with zero insulation. In-between the brick and the 2 x 4 framing is the sheathing and I believe a small drainage cavity gap in-between the sheathing and the brick about an inch or so. The sheathing as far as I can tell is horizontal planks of wood, which I believe has tarpaper on the side facing the brick acting as an air/water barrier. Recently, I signed up for a retrofitting winterizing program with our Natural gas utility company, helping resident to decrease utility costs due to inefficient insulation and to help lessen our carbon foot print. I have qualified for the program but I have some reservations.
They are offering to retrofit cellulose between the stud bay cavity’s. Seems like a great idea given I have no insulation but doing research I have heard this can be not such a great idea. What I’m learning is without a ploy vapour barrier on the inside, this can cause negative impact by building up condensation causing mold and or even rotting the wood structure of the framing. I’m not knowledgable enough on this topic to know if this is indeed a highly likely case with retrofitting cellulose. I’ve also heard certain paints and primers can act as vapour barriers on the inside, but wondering how effective that method of vapour barrier can really be?
We can get some harsh winters here and my home is definirtely most cold come January through March. Gas costs are certainly higher than they would be if it was properly insulated, so I do love the idea of moving forward but not if it poses serious risks to my health and slowly (if not quickly!) deteriorates the structure of my house. If that is the potential risk I’m presented with here, I’d much rather decline the offer and at a later point in time, tear out the plaster entirely, insulate with batts, add a proper vapour barrier and re-dry wall. It’s not ideal, the other method would be easier and cheaper but that’s why I’m here asking the question and hoping for knowledgable feedback on this.