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TOPIC: Ventilation

vents on metal roofs

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Am I correct in assuming that a square vent 7"x12" that is on an existing shingle room must be taken off and raised to accomodate a 5v being applied over furring? If so any trick to it? Also am I correct that the panel where the vent is should be put on first so it can be placed in the middle of a panel rather than on a seam ?
Guest User

10/21/2004
Yes, the vent will have to be removed and either re-installed or replaced. It would be best to avoid any of the ribs. Do not proceed with any aspects of the installation unless you have complete installation details from the manufacturer.
Guest User

10/23/2004
Mr. Reid responded generously to my closed cell question, except now I fear I might be on the wrong track. I live in florida and currently have a three dimentional ashphalt shingle over 1/2" plywood. Trusses are 24" on center. The roof is a 5/12 pitch and all ceilings, cathedral or flat are insulated and the roof has vented ridges Southeast metals, the 5 v manufacturer allows direct application over the 3 d as long as a #30lb felt is first applied. I am on the coast and that application satisfies 140 mph wind codes. As you are aware the panels are screwed at each seam of 24" and mid panel at about 12". I spoke with one technical advisor at Southeast and he said I will not always hit the trussess. That confused me and I will call back and ask why as it seems I should each and every time. I have read the product application throughly and there is no reference to screwing into the trusses. Secondly I am concerned about direct application over the 3 d is will a 26 ga. metal bend if walked on in that situation ? The possibility of bending the metal while stepping on it along with the strength of 1x4 screwed into the trusses would give me (assuming that the southeast metal rep was right). However if I decieded to use 1x4s I still have a 16" space inbetween so any walking on the roof would have to be on the furrings. That is how I came up with the idea of putting insulation inbetween the 16" 1x4s. However Mr. Reid pointed out I may not benefit from the insulation. Lastly, I prefer not to take the shingles off as I will be doing this by myself and the job is over 40 square. The thought of ripping off the shingles and applying #30 felt troubles me a little considering the rain we get down here. thank you for your patience.
Guest User

10/26/2004
No one is going to know the attributes and characteristics of SE's panels better than they do. However, generally, a quality 5V Crimp should successfully go over a dimensional shingle, especially when 30-pound is installed between the two. I second Al's previous answer to your insulation post, by the way. I would say that virtually all wind and uplift testing on metal roofing is done with fastening into the decking or purlins. It is impossible "in the field" to depend on hitting rafters with every fastener. You might very well luck out and have it work for you but, generally, that is not the case.
Guest User

10/27/2004