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Old 05-23-2013, 09:24 AM  
beachguy005
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Default soffit vent ?

Hi folks,
I have an enclosed 10' x 20' patio with a flat, pitched roof. It has a 24" overhang. Constructed with 3x6s, 16" oc. that is scabbed onto a hip roof.
I tore out and replaced the soffit boards and was going to replace the soffit vent but realized that the rafters are cross-blocked in at about 26" in from the tail ends.
Obviously this prevents any "venting" of the roof.
I live in SW Florida and I'm wondering if having a vent is even needed on this roof.
Thanks,



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Old 05-23-2013, 11:51 AM  
kok328
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What is on the roof (corrugated panels, asphalt shingles, EPDM)?
How many rows of 'cross-block' are beyond the first set?
Were the old panels ventilated?



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Old 05-23-2013, 01:36 PM  
beachguy005
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The roofing material is rolled. Each of the bays is blocked. I don't don't know if there are other cross blocks deeper in. The ceiling in the space is plywood.
The old panels were vented but so was a 10' section that consisted of 24" lookouts at right angles to the rafters.
I have a feeling that they installed the vents because they thought they should, not because that actually needed to.
The rest of the house is covered with a hip roof and the 24" overhang is vented, as it should be.
Thanks,

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Old 05-31-2013, 06:37 AM  
WindowsonWashington
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Should be vented in an ideal world.

Can you locate exhaust venting in the middle of the roof? Can you cut a cross over in the cross blocks?

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Old 06-01-2013, 03:50 PM  
GBR
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I wouldn't add more because you could get other problems. You may get a 10% reduction of ceiling flux (from 1/300 to 1/150) but an 8% increase in relative humidity for the wood framing comes with it; pp. 7;
http://www.google.com/url?sa=t&rct=j&q=attic%20venting%20in%20hot%20humi d%20climate&source=web&cd=6&ved=0CF4QFjAF&url=http %3A%2F%2Fwww.floridabuilding.org%2FFBC%2Fpublicati ons%2FAtticVentReportFinal.pdf&ei=DfBZUd-xDIfsiQLLmoGoBw&usg=AFQjCNHp4qU3vWO1vNceVxn2LqAJmH 81PA&cad=rja

Is there any insulation in this thin cathedral ceiling? Is there conditioned space below the plywood, or another attic space?

Gary
PS. 24" overhang doesn't require venting if exterior to attic space.

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Old 06-02-2013, 09:24 AM  
beachguy005
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Code:
Can you locate exhaust venting in the middle of the roof? Can you cut a cross over in the cross blocks?

Given that it's a flat roof and I have no access, I don't think I'd do that.


Code:
 Is there any insulation in this thin cathedral ceiling? Is there conditioned space below the plywood, or another attic space?
There is no insulation that I can tell. The space below has not been conditioned. It was a partially screened florida room with 16 foot sliders going into the house. It's now remodeled, totally enclosed and I'm hoping to remove the 16' sliders and open the space into the house.
I don't know if my ac unit can handle the additional 200 sqft. Nor do I know how much radiant heat I'll be getting into the room from this ceiling.
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Old 06-02-2013, 10:27 AM  
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If its not conditioned, don't worry about it.

If you decide to condition it, you could furr the ceiling down and insulate with rigid board if need be.

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Old 06-03-2013, 07:44 PM  
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http://www.buildingscience.com/documents/published-articles/pa-crash-course-in-roof-venting

Gary
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Old 06-03-2013, 08:22 PM  
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having a bad day



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