Brian writes from Canada: "I have read a number of your responses to heat loss from homes and nowhere do you mention air sealing of surfaces (especially attics) before or while adding insulation. In attics, unsealed vapour retarders and increased attic ventilation will usually not solve a wet attic problem. Dry out the damp house below and stop the upward moist air leakage from the house, then increased attic ventilation and vapour barriers are not needed!!!"

Thanks, Brian. I hope this is helpful to readers who have a wet attic problem.