What is the best way to insulate the exterior walls of an older home?

Geoff Kavanagh
Updated: Sept. 16, 2020

I have an older home in Toronto with plaster lathe walls with no insulation behind them.  I want to insulate the walls but not remove the plaster as it's still in excellent condition.  My house goes right to the property line on two sides and the exterior shell is cedar board/insulbrick covered by vinyl siding.  I would like to stip it to the cedar board, putting a wrap over it, but then what would you recommend for insulating after that given my narrow confines?  I really can't extend much more than a couple of inches without encroaching, three max...

Responses (2)

Lance White 2 years ago

My house is 110 years old and did this almost 20 years ago. I recommend insulating from the inside by filling the 2x4 cavity with two-component polyurethane foam. It is foam yes bet it does not off-gas and it flows in so as to form a vapour barrier and an R-16 wall. A few days of drilling the holes, then one day for the applicator to fill the voids, then another few day patching the holes--presto.

The added extra is the that the ridge foam adds to the structural strength of the walls. From a structural engineer – me.