What is the best way to insulate cement block walls?
Jackie writes from Ottawa, Ontario: “Only a quarter of my basement walls are finished – what is the best way to insulate the remaining walls (cement block foundation – built in the 1940’s). I understand that there is a new system available that can be applied to bare walls instead of the usual stud wall method.” Answer: The Owens Corning Cel-Lok® System with extruded polystyrene foam insulation board and metallic channels is most likely what you have seen or heard about. It comes in 1.5″ and 2″ thicknesses, which provides R-7.5 and R 10, respectively. The board can also be purchased as a special order in 2.5″ thickness (R-13.5) and that would be sufficient to meet the new Ontario building code requirement of R-12 for basement walls, in place since January 1, 2008 for new construction. You might want to increase your R-value.
