William liked my recent column on roofs in the Ottawa Citizen, especially the part about using zinc strips to prevent roof moss from forming. Trouble is, someone has since told him that zinc roof strips are not permitted in Canada.

It’s always surprising to me how often people present things as fact even though they bear no connection to reality.  Zinc strips are certainly permitted on roofs in Canada, and every building supply outlet where I live sells zinc for the purpose of roof moss prevention. I always install them on every new shingle roof I put on. The strips go up along the eaves, peeking out an inch or two from under the cap shingles. Rainwater dissolves just enough zinc to prevent rooftop moss and the shortened shingle life it brings.