venting/cooling metal roof

Guest User
8/18/2012
My house has no eave overhang and no vents at the eaves. There are two gable vents but they do not allow enough cooling to prevent shingles from overheating which results in a reduced lifespan (about 15-years). Do metal roofs have ventilation between the roof deck and the metal shingles?
Todd Miller
Isaiah Industries, Inc.
8/18/2012
Metal shingles, depending upin the product, have some degree of thermal break between the metal and the roof deck which can be very helpful. Some metal products can also be installed over battens for a greater thermal break or even for active venting. You can also create an actual cold roof through the addition of sleepers over your rafters and a layer of decking. Another product out there to look at is ThermaDeck -- an insulating ventilation product which can be incorporated.
Eric Novotny
An informed customer is the Best Customer!
8/18/2012
It was not the heat that killed your shingles. It has been proven that there is little difference in shingle peak temperatures between vented and unvented assemblies. The moisture is what killed your shingles in this case. Metal roofs can be vented in more ways than asphalt roofs, however, the necessity for ventilation does not change nor does where the effective location of it should be. In your case, you need to air seal and insulate the floor to start with. This will reduce the amount of moisture even getting into the attic and reduce your ventilation requirements. After that, there are plenty of ventilation ideas that allow for venting at the eaves (regardless of overhangs). If you deploy one of those options with a ridge vent, that is ideal. If there is no ductwork in the attic, putting rigid foam under the roof deck is not really necessary as it is much easier to just add insulation to the attic floor. Feel free to email me and I can walk you through all the options. Eric
Rochell Javier
We've top them all.... SInce 1981
5/9/2013
Proper attic ventilation is essential. It prevents condensation and dry rot within the attic wood structure and wood substrates, prevents mould, and prevents warping of the plywood. Proper venting also extends the life of the shingles and roof membranes. Provide ventilation in a ratio of approximately 1:300 of the insulated attic area. Ideally air should enter the vented soffit, rise as heated in the attic, and exit near the peak of the roof. Some people incorrectly believe that ventilation is only to keep the attic cool on hot summer days, and have even been seen to close their roof vents off for the winter. Nothing can be further from the truth. One should vent the roof at all times of the year, day and night, in order to keep the attic temperature as close as possible to the outside temperature. Most importantly, the ventilation is absolutely necessary to prevent winter ice damming problems on sloped roofs. Please see section on Snow & Ice on Sloped Roofs for a full explanation.
Guest User
9/30/2014
Can you please help me with this question? Metal vents should be spaced atleast_____inches Apart on a roof. (A) 12 (B) 16 (C) 8 (D) 24 Thank you for your help.
Eric Novotny
An informed customer is the Best Customer!
9/30/2014
Is this a ventilation question? The venting is a function of the volute required to properly vent and not a spacing schedule.

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