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TOPIC: Condensation Issues

Condensation or Leaking?

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We're a contractor and have installed dozens of metal roofs over the years, but have had one give us some issues this winter. 2+ years ago, we installed a black standing seam metal roof on 7/12 pitch, with 8 or 9 valleys. The owners moved in in Nov 09, and there were no issues the first winter. There was no real snow (<50") or long cold stretches that winter. This winter, we've had 100+ inches of snow, and typical northern MN winter. The issue presented itself in February 2011, when owner noticed drips on bottoms of valleys inside. Now for the details. Last fall (Nov 2010), a central humidifier was installed to balance out radiant floor heat system. Humidity I found out was set at 50% plus. Installation was from inside, board on board finish, vapor barrier (6 mil, not taped), R50 batt insulation, chutes, 1" air space, 5/8CDX, Ice/Water 2 rows eaves and valleys, 30# felt, and metal direct into deck. Seamless gutters were installed around all eaves and bottoms of valleys. From melting, water was flowing over gutters back onto fascia. Owner doesn't live there full time, and keeps house at 60 degrees. We did a blower door test and infrared scan, and noted some cold spots in valleys. 12" cold spot on 20' long valley. and some along the eaves. Do I try to fix this from inside or outside? Is this leaking or condensation? Is water backing up the ribs (capillary action)above ice/water shield? We are discussing removing roof and deck and working from above to seal insulation as working from inside is going to be considerably harder since house is finished. I only really want to do this once. Thanks Tom
Tom Dwyer

4/7/2011
One or two other pieces of information. Gutters were originally not planned, but house is built on slope with bedrock, so water needs to be moved away. It does seem to trap snow/ice in winter and backup? Thanks
Tom Dwyer

4/7/2011
Right off hand I am guessingt he issues are related to ice damming. Making sure the ventilation is good would be helpful and of course you could also go with heat tape on the eaves and gutters and downspouts but we all know that is problem-prone. These folks have some innovative solutions and may be someone you'd want to talk to: http://www.sol-ice.com/ Todd Miller
Todd Miller
Isaiah Industries, Inc.

4/9/2011
Water test the roof but my bet is going to be ice damming as well. That is a real kick in the pants. Sorry to hear about it as that is an expensive repair. I would suggest that you get the home blower door tested and see where the air loss is first. It may not be where you think it is coming from and the fix might be easier than you think. Get a qualified (should be plenty in MN) building analyst to look at the home with Infrared imaging and the blower door testing. That will tell you were the air leakage is from. Eric Novotny
Eric Novotny
An informed customer is the Best Customer!

4/11/2011
Thanks for response. Am I understanding that even though we thought we had the roof vented, somehow the ventilation is compromised? And if so, is the water then leaking through the roof metal seams as it backs up? And if yes, is the best answer to open from above and address the issues? Thanks again. Tom
Tom Dwyer

4/11/2011
If the roof deck is not properly sealed and airtight, putting and R-100 down does not mean squat if there is a bunch of hot air moving up through the insulation. If the venting is blocked, that warm air is going to melt snow and create ice dams. I think a good inspection of the venting and potentially a blower door test are a good place to start. Eric Novotny
Eric Novotny
An informed customer is the Best Customer!

4/11/2011