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TOPIC: Ventilation

Vented attic meets non-attic roof space...what to do? Contractors disagree.

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I live in alaska and am looking at getting the roof done. We can and do get a bunch of snow here and it gets COLD sometimes. I have an area of my house (see attached picture) where a vented attic space butts up against what is now a hot roof (that is going to be converted to cold with 2x4's over icenece foam insulation). The question is this. One company said there is nothing to do they are seperate spaces and will no be touched. The other company was concered about the ventilation in the roof above where the roof meets the attic rooof. He was talking about conecting the ventilation between the garage attic and the new converted cold roof. Making some sort of hole of airpathway between the two. He also made the comment of using 2-3 of the "whirly" stands/vents, or something like that to help with the venting. Can anyone shed some light on this? Is one way right or wrong? Is there any benifit to one wat over the other?
Guest User

4/11/2010
Pics from inside the Attic garage.
Guest User

4/11/2010
More pulled back view from within the attic space showing some of the roof of the garage.
Guest User

4/11/2010
The two roof line that meet between the T&G roof and the attic roof will need to be treated the same in terms of rigid foam and purlins for a vented roof because you will not be able to accommodate the different elevations. I would still air seal the accessible attic spaces and blow in extra insulation but that is as a result of trying to weatherize those sections of the home. Instead of putting ice/water over the roof deck that is inside the attic space, you could just air seal those spaces with spray foam while it is up there air sealing the attics. You might as well treat that small attic in the same way because the difference in elevations will look odd. Again, I would still air seal and insulate that attic space. That pdf that I sent you the web link to before is probably the most aggressive and sound way to approach this roof. The roof deck will be insulated and you will have an air space for over deck venting. Eric Novotny
Eric Novotny
An informed customer is the Best Customer!

4/11/2010
I would keep them as two different spaces. What sort of roofing material do you plan to use? Todd Miller
Todd Miller
Isaiah Industries, Inc.

4/11/2010
[email protected] - thanks. That is a thought. Just build up the roof over the attic where it meets the house roof to same thickness. Then no worries about getting the airflow. Sorry, I'm confused about "air sealing" the attic space. It will be getting a lot of insulation blown in this spring to help keep the heat from the garage and entry area from rising up into it. However, I thought some air exchange within the attic space was needed? On the front of the attic there is a louvered hole open to the outside. Are you saying this areas should be tottaly sealed off or am I misunderstanding? (and Yes, I am looking at that PDF again). In fact I may print it and give it too the company who seems to have the best references and longevity and basically just tell them how I want it done. Sadly it seems almost like some of the guys I meet so far are just looking for the easiest and fastest way to do the job, not the "best" way. Todd - thank you too. Both companies are trying to steer me toward shingle. Telling me they are cheeper, have great fire ratings, and last 50 years. Taht being said my intention (unless astrnomically out of my price range) is to use metal. [email protected] mentioned a stone coated metal to help keep some of the snow from sliding (the roof slope down right over the entry, over a deck, and the walkway to the front door. Decra seems to have some nice products. Still researching. There is another metal system, "Interlock". Saw them att he home show. They have some testimonials from Alaskans on their website so I may take a look at the too. I am open to any thoughts or advice regarding products or manufactures. I am very much in infomation gathering mode. That being said, thank you very much both of you for your experience and insight. One of the roofers even said that "clearly you are educating yourself". This is a big job. I want to understand it and in that sleep confidently that it was done right. Thanks for helping me.
Guest User

4/12/2010
When I say "Air Seal" I am not referring to the sealing off the soffits, gables, or other attic venting. Air sealing has everything to do with fixing the incomplete pressure barrier (Air barrier) between the living space and the attic space to prevent warm, moist air from migrating into the attic space. We spray foam all of the penetrations, build enclosures around recessed light fixtures, seal all of the top plates of interior and exterior walls, and address any major bypasses. Once all of the air sealing is done, we then go in and make sure that soffits and other attic vents are unblocked. we will install vent chutes where necessary to direct attic air flow right up the backside of the roof deck to keep that surface cold. The last step is blowing in borate only cellulose up to an R-49 to get the attic up to snuff from a thermal standpoint. That pdf that I sent you in the best way to approach a warm side roof issue by creating a complete thermal break and providing under deck venting. In this application, I would do the same approach as mentioned on the shared attic with the warm roof, spray foam the exposed warm roof in the attic, and still insulated and air seal for building efficiency. Eric Novotny
Eric Novotny
An informed customer is the Best Customer!

4/12/2010
Excellent....thank you for your time...much appreciated! I now have a much clearer understanding of what should be done. Now to decide on materials and an outfit to do. I hope one of these guys comes in here and presents the ideas that have been shown to me here instead of me having to suggest it to them. That would really be nice since these people are the pros.
Guest User

4/12/2010