Return to Installation
Return to Forum
I'm getting ready to install a new metal roof on my house. 125 year old two story farm house, in a pretty dry climate of eastern CO. Relatively low humidity year around.
Currently the roof is not vented at all, and never has been as far as I can see. No gable vents, no ridge vent, no soffit vents. I know the standard would be to have soffit vents for intake, and ridge vents for exhaust.
The 2nd story on my house the interior ceilings follow the roof line part of the way, so in each room upstairs the ceilings have two partial cathedrals on each side, before the ceiling flattens out. My attic is insulated with blown in insulation.
The cathedrals are insulated all the way down to the soffit and fascia. I know this because while I was stripping the existing asphalt shingles off, and drip edge, one of the fascia boards came off, and the blown in insulation started falling out.
Question - can I just vent the ridge, and that be sufficient enough to let the attic breath?
Otherwise the only way I see to install soffit vents, and have them work, is to remove the blown in insulation in the cathedral parts, install those styrofoam rafter vents, and try and stuff a bat of R-13 in there. My rafters are only 2 x 4's.
I'm using Titanium UDL 30 Synthetic Underlayment, and pro panel metal sales tin. I stripped the entire roof down the the substrate, and fastened the UDL 30 on the roof already.
Just trying to figure out how to vent the roof before I begin installation.
I'd prefer to see intake vents, obviously. My concern is the metal may drop the roof deck temperature enough to cause condensation in the roof decking that never occurred before. If you install a ridge vent without intake vents, it will pull air from someplace. It could pull air in one side and out the other, bringing in rain and snow. It also could start to pull air in through the walls of the house which could lead to condensation in the living space.
Any chance you can post up some pictures. The reality is that if you haven't had issues so far, nothing about a metal roof should chance that.
What can happen if you have an open deck is that the metal can become a cold and condensing surface without the right insulation and isolation from the cold meeting the warm moist air.
Hi Eric, yes I can post some pictures, what would you like to see?
Are you saying I might be able to get by without venting my attic at all, since it has never been vented?
It's my understanding that since Titanium UDL 30 is a vapor barrier, the attic needs sufficient ventilation. Am I wrong thinking that?
Picture of the inside attic space would be good. What kind of steel roof are you doing? To be honest, if you are doing a standing seam roof, the easiest thing to do would be to ventilate the via gable end vents.
Right now, the attic is most likely acting as a conditioned space if it is sealed up. If you haven't had any issues to this point, nothing about doing a metal roof will change that and I assure that the roof was not "breathing" through the asphalt shingles.
From the standpoint of making the entire assembly work and perform better, a bit of rigid foam to the exterior (on top of the roof deck) would only make the home feel better and thermally uncouple the roof framing from the exterior. In doing such, you would be moving the framing inside the warm wall and breaking that thermal bridge.
If the home isn't "sweating" now, I wouldn't add a bunch of ventilation for the sake of ventilating. The reality is that as the attic is working now, that space is probably functioning as conditioned.
I'm putting metal roof on my double wide..is it ok to take all roof vents out? And put gable vents in and or ridge vent....do have vented soffit
If the soffits are present and open, that would work best with a ridge vent.
If you would like to reply to this thread, please
If you do not have an Ask the Experts forum user account,