Are All Winter Time Roof Leaks Caused By Ice Dams?

We recently visited the home of a daughter of one of our customers. Our company had installed an ice dam prevention system in Franklin for this customer and his daughter reached out to us with a water damaged ceiling around a skylight. That is what you see in the picture. When she called she indicated that she had an ice build up around the skylight but no snow on the roof. There was significant water staining and wetness around the skylight and in the master bedroomSkylight and attic condensation water damage adjacent to this bathroom. She hired a restoration company to deal with that. The problem occurred after a long spell of below zero temps (some even -10 to -20 below zero) and then a warm up. All of this background info is important to understanding what caused her problem.

When I arrived at her home, she showed me the damaged area. I could see a skylight with a chase leading from the bathroom ceiling to the roof where it met the skylight. There was also an exhaust fan right next to the skylight. The un-insulated ducting was partially detached from it. I could also see the fiberglass batt insulation had been removed as well as blown in fiberglass insulation. I notice, too, that the 'scissors' style trusses did not have an 'energy heel'. I accessed the attic through the adjacent walk in closet. (The access was through an attic access hatch or scuttle hole which had a piece of drywall set on a wood trim ledge). Much of the attic appeared normal. The homeowner reported that when the restoration company opened up the ceiling, there was frost on much of the underside of the roof deck. They told her this was normal in the winter. My observation also revealed frost and moisture on the underside of the roof deck which also extended over to the bathroom adjacent to this one. So, was this a roof leak caused by the ice around the skylight or was it something else?

After observing the frost and moisture buildup and hearing about report from the restoration company, it was concluded this damage was caused by condensation build up. With the recent extreme cold (it hasn't been this cold for this long in 50 years or more here in Wisconsin), problems with air moving from our conditioned living space into the attic are magnified. Typical of new construction, poor vapor barrier sealing allowed air to escape into the attic. The bath exhaust fan housing was poorly sealed. The exhaust ducting was un-insulated. The attic scuttle hole was not properly air sealed. All of this resulted in warm air leaking into the attic. The warmer the air, the more moisture it contains. The moisture in that air condensed on the underside of the roof deck and then froze because of the extreme cold. When the outside air temperature finally warmed enough, the frozen condensation melted and trickled down causing the damage. 

What could be done to prevent this? Some say ventilation solves attic condensation issues. In this case, we can see how wrong they are. In fact, roofing manufacturers often tout their ventilation products as being the cure for this problem as well as ice dams without much good science behind it. Complex roof designs, ridge and roof vents being covered by snow, large temperature differentials required for passive drafting (roof venting), and unrestrained heat loss are reasons with venting cannot solve these problems. Providing an air tight barrier between the living space and the attic along with proper insulating techniques would have solved this issue. If no air escapes from the living space, no moisture for condensation. 

We made several recommendations to this customer and referred her to a specialist that will show her what to do in order not to repeat this problem. So, not an ice dam problem. Our products are not the solution to every winter time leak. But, our experience can point you in the right direction. We will not sell you something you don't need or that won't solve your problem. Sometimes the proper fix is not something we supply. Let us know if we can help.