The copper roofing was material that was available during the Great War; it was not a gauge that an engineer or architect would specify today. The technique used in its application was not up to snuff, many of the craftsmen being away at war. Acid rain had been having its way with it. (Every bronze statue in Ottawa also had to undergo restoration and have a protective coating applied. The corrosion is already coming back.) Quite simply, the roofs had to be replaced about three quarters of the way through their lives. (The Fairmont Chateau Laurier, with a similar roofing system, is replacing its copper sheathing, but it got the expected 100 years out of it.)