Preventing curling asphalt shingles - November 27th 2001



Roof ventilation the cause of curling asphalt shingles. Are your asphalt shingles showing signs of curling as well as discolouring around the flashings of chimneys and along the soffit lines?

Asphalt roofing quite commonly known as duroid roofing is affected by insulation as well as ventilation causing curling, cracking and certainly discolourment along the soffit lines, ridge lines, as well as valley lines in a roof. This is caused from improper ventilation. Ventilation is very very important to a roof cavity in that the warm moist air must be vented out into the atmosphere. If ventilation to the outside is not allowed then condensation taking place underneath the roof sheeting will migrate up into the asphalt membrane causing frost balling as well as ice damming on the outside wall above the soffit lines. As proper ventilation is very important when putting on a new roof you may want to consider ridge venting which runs along the entire ridge be it on a cottage roof or a gable roof. Soffit venting is very important as well, as long as you put adequate ventilation making sure that insulation stops are in place holding back ceiling insulation thus allowing the air to migrate up from the soffit up into the attic cavity and out a roof vent. Turbine vents are quite popular as well, but it is very important to make sure that all attic cavities are sealed, such as your attic access into the cavity of the roof with weatherstripping, as well as all ceiling light fixtures being sealed under ceiling insulation with 6 mil poly and acoustic adhesive caulking and insulation replaced over top.