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TOPIC: Ventilation

New Metal Roof and Sheathing, Insulation Profile Condensation

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I am planning to build a new monitor style building including an apartment up stairs and heated garage below. The building will be located in the Northwest near Seattle, Washington on Whidbey Island. Yes, the building will be primarily in the shade 90 percent of the time. I have been taking to roofing contractors and they all have different recommendations on the metal roofing profile. One example was 1/2-inch OSB sheathing plus 1/2 to 1-inch insulation board and another 1/2-inch OSB plus 30# felt paper for vapor barrier. I am looking at raised seam metal roof on 12-inch centers. Another contractor recommended two layers of 1/2-inch soundproof fiberboard over the OSB plus 30# felt paper for vapor barrier. I also need a relatively hard sheathing under the metal roof since the lower roof section needs to be walked on to maintain (wash) the window. Besides the manufactures recommendations, what is the best profile considering the roof will have full length ride and soffits vents? Ceiling will have R35 insulation and walls have R19. Ceiling space will have ventilation between the insulation and roof sheathing. The exterior will also be metal, siding will have 1/2-inch OSB and 30# vapor barrier including 2X6 inch wall for R19 insulation. What is the best roof or siding profile for metal roof and siding?
Darrell Pittman

12/29/2005
There are certain advantages as walkability in choosing a standing seam panel that installs over solid sheathing. Sounds like you have done some research. I am unsure of the term "Monitor" style building and you do not mention what the roof slope is expecially on the lower roof. Do make sure that you vent it at the eaves and where it abuts the wall which may mean standing it off the deck. There are other options such as cleat clamps that allow a walking platform to be installed raised over the metal which you may want to consider. As to the profile, once you identify all the performance reqirements of the roof system you may natrrow your choices down.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/2/2006
I am still in the design phase of my project but the roof slope; pitch is 4/12 and may go to a 3/12 pitch. I hope to satisfy the metal roof requirements before finalizing the design plans. The Monitor style building will have a lean-to section of roof against the main structure, rap around porch that will require outlet vents at the roof to wall transition. Darrell
Darrell Pittman

1/4/2006
Walking should be kept to a minimum on all roofing materials. I would recommend operating windows that can be cleaned from the inside. Certainly you need to watch for condensation etc and it is best to keep the roofing material off the deck, with a good underlayment and ventilation. There are a number of profiled vented closure strips that will work well for this that fit under the panels at the eaves and under the flashing at the wall. There are some brether mebranes that would help elliminate the strapping but they do limit the ventilation. Have a look at our products at www.duraloc.com as most mount on battens.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/5/2006