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Old 01-15-2008, 01:18 PM   #1
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Standing Seam Ridge Vent


I need advice please.I had a new standing seam roof installed on my newly framed house.The whole house has cathedral ceilings.The panels are boxed at the end were they meet the ridge.The ridge cap is snapped onto the z-channel.The z-channel was cut approximately half an inch short on each end.This is supposedly where the air vents.This ridge vent I paid for seems to be just a regular ridge cap with altered z- bar.It seems "homemade".Should I have received a "manufactured" ridge vent or is this the normal procedure?Thanks!

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Old 01-15-2008, 02:30 PM   #2
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Standing Seam Ridge Vent


You probably would do best by checking out the website and installation manual from the manufacturer of your brand of panels.

Custom fabricated is an accepted norm for the architectural sheet metal industry. SMACNA is the predominant organization, but they do not list their specified drawings for free.

If you provided pictures, maybe we could offer a bit more judgement on its current potential functionality.

Ed

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Old 01-16-2008, 06:55 AM   #3
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Standing Seam Ridge Vent


Thanks Ed The Roofer for the info.I dont know where my roofer gets his rolls of metal from.He wont tell me.He forms the panels on his own equipment.The color is Hartford Green.There is a local supplier called MBCI which is where he might get it but thats just a guess.Ive tried talking to him but he just brushes me off.I Think what has occured is he subbed my house out and thats the way the subs vent their houses.The cheap way.The way I see it its a regular ridge cap with altered z-channel.I dont see how they calculated proper air flow or exhausting by just snipping the ends of the z-channel.Ill try to get pictures.Thanks again Ed The Roofer.
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Old 01-16-2008, 07:43 AM   #4
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Standing Seam Ridge Vent


http://www.rooferscoffeeshop.com/sho...&file=2912&s=0

Hope this helps. Several shops or mock-ups done in my shop, and a couple on the job. Flat pans and Z equal eventual leaks. Turned up panels and baffles prevent leaks. I was experimenting in the shop for extreme venting in Alaska for wind blown snow.
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Old 01-16-2008, 03:07 PM   #5
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Standing Seam Ridge Vent


MBCI probably has the most exhaustively intense and detailed set of specifications and detail drawings I have read.

Get their manual.

Ask the contractor which material supplier he purchased the panels from. Didn't you ever ask or get offered that information before you signed a contract? There is a great difference between coatings and colorings and guage thicknesses of various products.

Ed
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Old 01-18-2008, 08:43 AM   #6
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Standing Seam Ridge Vent


To Ed The Roofer.Unfortunetely my contract was a good ole boy hand shake.Live and learn and go broke. I calculated my roof square footage which was 1728 and used the 1/150 formula.According to this it comes up to 11.5 sq.ft. nfva.I used the 1/150 formula because its all cathedral roof .No attic space.Is this assumption right?Is my soffit intake venting supposed to be equal or greater than this?One more thing.I added up every hole the roofer left on each end of the z-bar and total sq.ft. was 1.6.THANKS.
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Old 01-18-2008, 10:51 AM   #7
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Standing Seam Ridge Vent


Quote:
Originally Posted by A.Pierce View Post

To Ed The Roofer.Unfortunetely my contract was a good ole boy hand shake.Live and learn and go broke.

I calculated my roof square footage which was 1728 and used the 1/150 formula.According to this it comes up to 11.5 sq.ft. nfva.I used the 1/150 formula because its all cathedral roof .No attic space.Is this assumption right?

Is my soffit intake venting supposed to be equal or greater than this?One more thing.

I added up every hole the roofer left on each end of the z-bar and total sq.ft. was 1.6.THANKS.
Will the contractor return your call to answer which product it is?

You need to calculate the "footprint" of the attic, not the entire sloped sections total square footage, although that will result in additional ventilation calculations, it would not be detrimental. The footprint would be the entire actual attic floor space, and by that I mean to pretent that the attic cast a shadow straight down onto the ground for all perimeter edges, and then do your calculations. Otherwise, you presumed correctly.

Soffit venting should be at least 50% of the total ventilation equation, but weighted in favor more for intake than exhaust if possible. A 60% intake to 40% exhaust would be ideal. But, since this is a cathedral/vaulted ceiling scenario, you absolutely require 100% continuous soffit fresh air intake ventilation.

I am not sure if I am understanding your method to calculate the ridge vent NFVA. The entire width of the hole should be "approximately" 3" wide. Different ventilation manufacturers have slightly different width specifications. With the proper type of ridge vent, you would get 18 square inches of NFVA per lineal foot, so when you have 144 square inches, you have 1 square foot of NFVA and keep on adding the total up for the entire length.

I am not sure of custom fabricated or MBCI or other metal panel manufacturers ventilation reported NFVA, but the results "should" be similar to the products that are sold for composition shingle roofing products.

Ed

Last edited by Ed the Roofer; 01-18-2008 at 10:57 AM.
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Old 01-25-2008, 09:49 AM   #8
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Thanks for your help Tinner and Ed.Ive solved my problem.My roofer refuses to cooperate so im gonna fill in between my rafters with 12 inches of closed cell foam so therefore I no longer need to vent.
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Old 08-04-2010, 03:29 PM   #9
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Standing Seam Ridge Vent


As an architect I have never seen a proper metal roof on any residential property anywhere in the U.S. If you do not have a metal roof system with concealed standoff slip clips in the seam to vent the underside of the sheet plus a fixed ridge and an expanding eave you might as well just keep what you have until it oil cans, cooks off the underlayment (which is most cases roofing contractors use build felts which will cook off in about 6 summers), leaks and fails as these will always do. You should just rip it off and throw it all away.

By not getting a manufactured metal roof that was tested to failure in high winds have a 20 year manufactures warranty and a 20 year no fade finish warranty, I am sorry you have thrown your money away regardless of what any roofing contractor has to say because going to a roofing contractor was your first mistake.

Most of these cheap metal roofs have a ton of exterior screws that attach the panel right through the exterior of the metal panel sheet right on top in contact with the underlayment which by using the old noggin putting thousands of holes in your roof which is a source of water migration into your substrate. It gets worse as the contact directly of the roof sheet gets so hot it bakes the membrane which is the worst on building felts. Along with the moisture through the holes and the oil canning deflecting the sheet and fasteners that tie the sheets together without the standoff clips and the vented system all the heat is transferred right into your house. Since your A/C system may not have taken this into consideration, all it will be doing is spending all its electrical energy trying to remove the excess heat and humidity out of your house and never cool off increasing the wear on the system, high electric bills and an increase in molds and mildew in your house.

Yes this may be more expensive but it is really cheaper after you throw your house away in a few years.

Take a look at IMETCO metal roofing system 300 to see what most good companies have engineered and provide. Also use an underlayment that is tested to take high heat without breaking down like MB Technologies SBS Modified Bitumen underlayment.

I have a good friend who has a company that replaces failed metal roofs on residential properties all installed by roofing contractors. He did 25 million dollars of roof failures last years just in the Tampa area all because the contactors sold the owners a cheap off the shelf untested pile of crap. Play hell trying to get those guys back. their warranties are usually up to one years and about 50% of them disappear over the border by the time the roof fails even within that time.

Next time hire and architect and have an air tight specification and those 20 years warranties and manufactures inspection throughout the process. That is how I have been doing this for over 20 years. If you go cheap you get cheap.

Oh by the way you should have at least 2" of rigid insulation under the roofing so the rain doesn't drive you insane as it pounds on the metal like a thousand Prussian soldiers riding horseback on your roof.

To experience this effect, place a frying pan on your stove until it is red hot. Take the frying pan and hold it about 3/8" away from your face and note the heat. Then take the frying pan and out it right on your face.

Which one is the hottest?

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