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I have a contractor installing standing-seam metal directly over an existing asphalt roof. My question has to do with moisture. It snowed about 12" here this weekend, and natually the first thing they did was to shovel off the roof. My concern is: could there be moisture that is trapped under the metal roof if it not absolutely, 100% dry that will cause problems in the future?
Secondly, the house is T-shaped and along one with a cathedral ceilings along one the top part of the T. There seems to be more heat-loss on that part of the roof, in that they noticed some refreezing in that part of the house. Presumably there's inadequate ventilation there...I don't know what insulation or airspace there might be, and there's no access to it. Do you think that cutting into the ridge to provide a path for trapped hot air via the metal roof's ridge vent is a good idea?
Thanks!
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It does take about 6" of snow to equal an inch of water so a little snow residue is typically nothing to worry about as it will evaporate over a short period.
The new building codes (finally) require that you need to ventilate a roof. For vaulted cathedral ceiling, they require 1" minimum of vented air space above the insulation, under the roof cover. Your refreezing may be due to inadequate insulation resulting in heat loss or from heat retention from the sun as it is not vented. You have an ideal time to upgrade the insulation at this time. Have the contractor check what you have and compare to the building code.
Next and most important is to have the roof installed up off the deck on strapping such that it is a minimum of 1" and allows for air to move vertically up the roof under the metal. Don't forget the underlay either. It is required by code unless the roof manufacturer has tested without it. Then you can ventilate the eaves and ridge with profiled vent mesh closures.
Hope this helps.
12/8/2003
Or copy this URL: https://www.metalroofing.com/spirit/comment/2482/find/Dura-Loc Roofing Systems, Inc.
12/9/2003
Or copy this URL: https://www.metalroofing.com/spirit/comment/2483/find/