New home construction metal roof install

Thad Opat
12/11/2013
Metal roof will be installed over vaulted ceiling with 12' tall walls. Plan to have closed cell spray foam for insulation. Metal roofing company wants to install some sort of double bubble foil facing outward. I was wondering if this would be best practice for metal roof or is there a better way. Have read about foil and condensation issues or waste of money without air space. So to sum it up (Vaulted ceiling>closed cell spray foam>roof sheathing>double bubble foil facing out>standing seam metal roof). Just want it done correctly without any issues and need professional advice so I am informed when speaking with contractor. If this is not correct then please state the proper sequence for best practices when installing metal roof. Thanks
Todd Miller
Classic Products, Inc.
12/11/2013
First of all, thank you for choosing metal. Based upon what I know here from your post, I do not see any detriment from installing the radiant barrier. However, yes, radiant barriers need an airspace to be effective. In this case, the "bubble" part is going to serve that purpose. My advice is this -- despite the claims I personally feel that in this application, the benefit of the radiant barrier will be minimal. Therefore, I would not pay much for it. You might also want to ask them for comparative energy studies for situations exactly like yours. I doubt they have any but it's worth asking,
Info @windowsonwashington.net
An informed customer is our best customer.
12/11/2013
+1 You need to have an airspace as Todd mentions for a radiant barrier to work. Otherwise, it is like insulating with tin foil...not effective. If the home is new construction, I would love to see some over deck venting a layer of rigid foam to the outside of the roof structure to uncouple the framing from the insulation equation. +1 on using metal and please keep us posted with some pictures.
Guest User
12/11/2013
So everything sounds okay but would be better with a layer of rigid foam for thermal break. How thick, what kind and do you put the double bubble over or under it. So as I am understanding it (vaulted ceiling>closed cell spray foam>roof sheathing>rigid foam insulation>dble bubble foil layer>standing seam metal roof?) Thanks
Info @windowsonwashington.net
An informed customer is our best customer.
12/11/2013
What size are the rafters? I would love to see 3-4" of rigid foam (poly iso with the last foil layer out), sleepers and plywood with some over deck venting, and then the roof. You could use just a tiny bit of foam inside the rafters that that point for the air seal and fill the remaining cavity with regular fiberglass or less expensive materials.
Guest User
12/11/2013
No rafters. Vaulted Engineered trusses 24" on center with about 2 feet of space to insulate. I can insulate on top of sheathing 3 inches if budget allows. Will have to check into price but you lost me after that I am confused by sleepers. I assume you are referring to furring strips? Also, what do you mean by over deck venting? Are basically stating to build a roof over a roof? Thanks
Info @windowsonwashington.net
An informed customer is our best customer.
12/15/2013
Yes. Furring strips and some over deck ventilation.
Guest User
1/6/2014
Huge moisture problem in me house - not yet moved in. Standing seam roof over tar paper? Spray foam and cellulose. Gable Vent and ridge vent.
Todd Miller
Classic Products, Inc.
1/7/2014
Elizabeth, please give me a call at my office at 1-800-543-8938 ext 201 and we will talk this through and hopefully figure out what is going on. For one thing, if you do not yet have drywall and a vapor barrier on your ceilings, then more humidity is reaching this area than should.
Info @windowsonwashington.net
An informed customer is our best customer.
1/7/2014
+1 Gotta know more about the home, area, construction, etc. Please contact Todd with all the details or post them up.
Guest User
7/14/2015
I had a metal roof installed on a new home 3 years ago. The contractor placed the metal roofing over horizontal perlings that were attached and to rafters. There is no moisture barrier. Fiberglass insulation is between the rafters. And the ceiling is a tongue and groove pine. Since we moved in, we have a lot of air drafts coming down from the ceiling along each wall. If it's windy during a storm, we will get water streaming down the outside walls. And eventually, water coming in between the tongue and groove pine. Should there be a waterproof barrier like felt paper or styrofoam, and any sheeting material like OSB? The insurance will pay to dry out the walls and to repaint. But since there is no signs of wind damage to the roof, they will not cover repairs. The contractor is avoiding us.
Info @windowsonwashington.net
An informed customer is our best customer.
7/14/2015
Picture of the outside?
Guest User
12/29/2016
I'm building a hunting cabin this spring and I have a roofing question. On a roof design with a 12 /12 pitch and 2 x 10 rafters spaced 24" apart, I'm planning on using 3/4" OSB sheeting, Do I protect my sheeting with tar paper than use double sided foil, than perlins over the foil to support my steel roof? If you could get me straighten out, I would welcome any help. Thanks.
Todd Miller
Classic Products, Inc.
12/29/2016
Yes, I would install underlayment even though the radiant barrier will then be installed.
Info @windowsonwashington.net
An informed customer is our best customer.
12/30/2016
Yes. You need an airspace for any sort of radiant barrier to work properly.
Guest User
1/9/2017
Hi my question is we have a metal awning I believe it's metal that my husband used as the roof when he enclosed Our Deck to make it into a sunroom we are now seeing wet stains on the ceiling that I'm guessing is from condensation this is also insulated so I'm guessing the insulation is probably wet what can we use once we tear down the ceiling to stop this condensation thank you very much
Todd Miller
Classic Products, Inc.
1/9/2017
If it is condensation, then you will need a complete vapor barrier between the living space and the roof -- to make sure that warm moist air from the living space does not reach the cool roof and condense.
Guest User
1/9/2017
thank you for getting back to me my second question will be what is a vapor barrier and does it go between the roof and the insulation ?
Todd Miller
Classic Products, Inc.
1/9/2017
A vapor barrier is commonly a heavy polyethylene, seams taped, and taped around the edges and any penetrations. It needs to go between your ceiling and the insulation. Moving it above the insulation (toward the outside) would be a mistake.

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