Vented Roof or not?

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  #1  
Old 03-26-15, 07:00 PM
J
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Talking Vented Roof or not?

Dear DIY Pros,

We recently moved into a house that had a "room and a half" above the garage that was a complete gut job.. had roof leaks in the past, animals living it, etc. I've now gutted the place, but am realizing there is no venting to the roof at all. I've read various articles and know that venting is usually done with gable vents (as is the main house from 1910), or soffit vents with ridge vents, but have already read that if you insulate enough and properly, you don't need to vent at all.

The original space had very odd cardboard like "drywall" tiles under which it looks like cellulose insulation was blown both behind the walls and above the ceiling tiles. It was very uneven and settled horribly wrong over time...

So that's some background.. now my question... I am planning on keeping the roofline as it is if possible, but obviously want to vent/insulate properly for both energy savings and to do good by my roof. Being that there are no soffit vents or ridge vents in the existing building, should I just fill the joist cavities with fiberglass bats, put up a vapor barrier and call it a day? OR should I somehow add soffit vents and a ridge vent, but in the proper baffles and make it more "modern"?

Any input would be helpful and I know this is sort of vague, but I'm hoping someone asks me some questions here as I'm not really sure what to put up to start...

I've attached some photos that show the space. I'm planning on insulating up the triangular rafters, and keeping the small fake/lower' ceiling 2x4's to put recessed light on and maybe run some heat pump lines above.

Thanks in advance, I know nothing about venting!

Best,

Jay

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  #2  
Old 03-27-15, 04:40 AM
J
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For better ansewers you need to add your location to your profile.
That attic looks like it was never intended for a living space, what size are the floor joist?
Is there a code compliant real stairway?
Only way you can get away with no vents is if you have the rafters spray foamed.
 
  #3  
Old 03-27-15, 05:21 AM
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Thanks joecaption!

The house is in Philadelphia, PA, and I know it has been used as a living area by the previous owner.. just a nasty one that's fallen into disrepair. The floor joists are old-school/true dimensional 2x12s over only a max of about a 14ft. span.

The "clubhouse" as we're calling it DOES have it's own stairs/entrance from the elevated yard (I've attached another angle that shows the door entry into the main room).

Is your comment about spray foam just due to the fact that I have to get up to the necessary R value? If so, I was thinking about sistering the rafters for a bit of extra depth, then maybe using some rigid foam board on top of that under the drywall?

If I don't do that, if it possible to re-do the soffits (some of which are damaged anyway) and add the vents to them as well as cut into the ridge and add a vent there? Doing that though and adding the baffles, I think I'd even have more a challenge getting up to the correct R value if that's the concern...

THANK YOU!

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  #4  
Old 03-27-15, 08:10 AM
B
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Hi javelin and welcome to the forum.
You are at a good point to be asking and asking the right questions. That space is essentially a cape, small side attic spaces, slope, and an upper attic. I'll attach a link showing two insulation options. Another link for minimum insulation levels.

Your ceilings in PA will be either r-38 or r-49 depending upon where in PA you are located. Slopes are sometimes treated differently from a flat ceiling and allowed some relief from the r-49 in the ceiling. I can search.

How deep are your current rafters? You want a minimum of 1.5 inches of air space for ventilation above the slope insulation.

As for reaching code, that is a point many home owners don't feel they are required to follow. Here's the catch. I just helped two friend/family members go through buying a new home. Key points when buying are to search for permits and inspections and if missing the selling price takes a BIG hit. In today's computerized world, every step you take will be recorded and either used to your advantage or disadvantage. Get your permits, build to at least minimum code, and have everything inspected, even if not required. And document it all. Not only will you end up with a great energy improvement, but it will add value to your home. Save along the way and profit in the end.

Air seal, air seal, air seal.
Bud
Two Ways to Insulate Attic Kneewalls - Fine Homebuilding Article
https://energycode.pnl.gov/EnergyCodeReqs/
 
  #5  
Old 03-27-15, 08:48 AM
B
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Here is a code review for PA. Local areas can still have variations but this should get you close. There is a section that states "500 ft2 or 20% of ceiling area of cathedral ceiling, whichever is less, is allowed to have R-30 insulation".

Bud
https://www.energycodes.gov/sites/de...sylvania_0.pdf
 

Last edited by Bud9051; 03-27-15 at 08:49 AM. Reason: addition
  #6  
Old 03-30-15, 01:57 PM
J
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Thank you Bud! I've actually already read that article from FineHombuilding (and many others - So I'll put R-38 up there in the ceiling as I think it will fit in the 8.5" deep bays... I'll put in the baffles behind, and I'm thinking I'll cut in a ridge vent on the roof as well as add some soffit vents to keep the roof deck happy... I plan on insulating the whole roof deck, thereby making the space behind the kneel conditioned space to run ductwork/plumbing/etc. Anything else obvious I'm missing?

Thanks for your input!

Jay
 
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