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-   -   Florida metal roof dilemma. (http://www.diychatroom.com/f9/florida-metal-roof-dilemma-146495/)

DIYorDIEtrying 06-09-2012 08:35 AM

Florida metal roof dilemma.
 
I have a shingle roof that is getting on in age, and it has survived every hurricane to date with only minor problems.
So we want to change the roof to a metal roof before the the next major storm makes that impossible. To do until next year.
I received 4 quotes, and none mention replacing the ridge vent in the process of getting metal.
The one roofer who I asked about a ridge vent, said that he would not put a ridge vent on the metal roof, but he would add a couple of goose neck vents to the back side if I asked for it.
The job included Wip 250 rubber underlayment. The company that makes that has an application note that I got from their web site. The application note clearly says that the roof has to be vented.
I read a Universaty of Florida paper on roofing materials, which I found very interesting. It covered a lot of good information on studies they have done on roofing. One of the things they explain is why the vent is needed, and how to go about having a sealed roof. It was clear to me, that the sealed roofing system is best done when a new house is built. This is because there is a radiant barrier installed on the inside surface of the roof, and insulation is not installed above the ceiling. The attic becomes a conditioned space, removing humidity, and lowering the temperature. The increased savings comes from having the AC vents in a conditioned space, reducing the load on the Air Conditioner.
So I understand that the primary reason to vent a roof is to reduce moisture, and the secondary reason is to reduce heat. The metal roof achieves the secondary goal of reducing heat, but not the moisture. This means that when the conditions are met, the moisture levels can start the growth of mold and mildew.
Why am I finding it hard to get roofers in Florida to add a ridge vent to a metal roof? Are two goose neck vents enough to do the job?

The job entails a 24 gauge seamless roof, with Wip 250 rubber underpayment, and all fascia covering made from the 24 gauge metal from the roof. The fascia covering will be form fitted around the fascia, in the same color as the roof.

Thanks to everyone who takes the time to read this, and comment.

Joe

tinner666 06-09-2012 09:37 AM

That's one HUGE chunk of steel needed to make a seamless metal roof. Must weigh 1,300 pounds. :eek:

It has to be vented. Ends need to be boxed, insect screen needs to be installed under the metal at the ridges. The only good metal roof there will be a double seamed, standing seam roof, cleated 12" O.C.

OldNBroken 06-09-2012 09:41 AM

I highly suggest you contact Imetco about their Series 300 system. They are mfr'd right above you in Atlanta. It'll be on the high end but well worth it. It is by far the highest engineered standing seam I have ever seen on the market.

Like every system, be more concerned about WHO is putting it on than WHAT is being put on. I suggest you promptly dispose of the proposal from anyone who said they would not include a ridge vent, especially the one who mentioned "goosenecks" instead as they are not someone you want working on your roof. Every mfr out there has a vented ridge detail of some sort.

Series 300 has a very good and stout stainless steel venting system and offer a watertight warranty

As far as underlayment, don't be as concerned about the mfr. Just make sure it is an HT underlayment. Specifically for use under metal. OC weatherlock HT is another good one, reasonably priced.

Best of luck. Keep us updated.

DIYorDIEtrying 06-09-2012 10:39 AM

The roof is going to be 42 square of 24 gauge Galvalume.

The next contractor I asked about venting said that he will add venting, but no ridge vent. That is two in a row that say NO ridge vent. He said he would add off ridge vents on the back side. He also told me that I should wait until November, or December to do the roof.
He will quote the vents, and he said that they would not be goose neck vents. He told me the size, but I don't recall if he said that the standard ridge vent is 2", and he would insall 3 to 5, 4 foot by 4" vents. I could be wrong. I asked for the quote, and I may ask for a drawing, or picture of the vent he wants to use.

[quote=tinner666;939692]That's one HUGE chunk of steel needed to make a seamless metal roof. Must weigh 1,300 pounds. :eek:
quote]

Windows on Wash 06-10-2012 07:57 AM

I am not sure I understand.

Is your insulation layer along the underside of the drywall (i.e. vaulted ceiling) or a traditional attic?

DIYorDIEtrying 06-10-2012 08:25 AM

I'm not sure what you mean, but I would say that my insulation is on top of the drywall for my vaulted ceilings. It is also on top of the dry wall for most ceilings except for the area over the garage.

Quote:

Originally Posted by Windows on Wash (Post 940236)
I am not sure I understand.

Is your insulation layer along the underside of the drywall (i.e. vaulted ceiling) or a traditional attic?


Windows on Wash 06-11-2012 06:21 AM

They are therefore both vented attics and technically the ventilation should currently be handed by soffit and ridge venting.

Venting the metal roof above deck is probably not a must but does help keep the roof a bit cooler and more venting is certainly not a drawback in this case.

Gary in WA 06-11-2012 02:01 PM

Your house location and HVAC location warrants unvented roof assemblies. "So I understand that the primary reason to vent a roof is to reduce moisture, and the secondary reason is to reduce heat. The metal roof achieves the secondary goal of reducing heat, but not the moisture. This means that when the conditions are met, the moisture levels can start the growth of mold and mildew."-------- The color of the roof is of great importance: http://www.professionalroofing.net/a...2/feature2.asp

You don't want venting to limit moisture from outside, the pressure/moisture flow is from exterior to interior (you certainly don't want MORE venting). http://www.joelstiburek.com/topten/south.htm
Mastic seal all HVAC ducting, air-seal all penetrations from rooms/wall plates/drywall ceiling-wall joints below, including crawlspace hole in flooring above. Weatherstrip the attic access against air leakage. Install foam outlet/switch covers (ceiling/wall) to stop infiltrating warm air. Install 1/2" foil-faced foamboard between rafters (against roof sheathing) to negate the dew-point from condensing in cavities, wetting your new air-permeable insulation. Close-off your soffit vents if deciding to go this way. Check with the metal manufacturer for compatibility.

http://www.buildingscience.com/docum...humid-climates

http://www.buildingscience.com/docum...he-humid-south

http://www.buildingscience.com/docum...archterm=attic+

Gary

ionized 06-13-2012 08:53 PM

See the links posted by GBR and seriously consider sealing your attic and foaming the underside of the deck. You are in a hot, humid climate and you have air conditioning. The rules for attics in hot climates do not apply. The rules for pre-air conditioned homes in hot, humid climates do not apply. Vented attics are a Yankee plot to get even for the War of Northern aggression.

Windows on Wash 06-14-2012 06:29 AM

Quote:

Originally Posted by ionized (Post 942949)
See the links posted by GBR and seriously consider sealing your attic and foaming the underside of the deck. You are in a hot, humid climate and you have air conditioning. The rules for attics in hot climates do not apply. The rules for pre-air conditioned homes in hot, humid climates do not apply. Vented attics are a Yankee plot to get even for the War of Northern aggression.


:laughing::laughing:

Spray foamed roof decks are great but I see a ton of them without proper depth, missed spots, and they aren't cheap either.

ionized 06-14-2012 09:03 AM

Quote:

Originally Posted by Windows on Wash (Post 943156)
:laughing::laughing:

Spray foamed roof decks are great but I see a ton of them without proper depth, missed spots, and they aren't cheap either.

Quality control is certainly important.

Remember, the alternative to sealing the attic is making sure all those holes between the attic and the rest of the house are sealed.That includes any perforations for cables, pipes, ducts and those so popular can lights. If you seal the attic, you can forget all of those and the additional ones that the cable guy and others don't hesitate to make and don't worry about sealing up. (They won't put holes in your roof because you will notice right away.)

jdoorn 02-12-2013 04:44 PM

I'm going to agree an the necessities of ridge vents. I think that not creating a properly ventilated roof system is a gamble that could end up costing you in the end. I hear these guys make some good ridge vents: http://www.quarrix.com/products/vent...ns/metal-roof/
But beyond that, I'm not sure why a contractor would refuse to put them in. That's really odd.

747 02-12-2013 05:00 PM

Ask teetor is he still around.:yes: He is out of Florida


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