ventilation calc. and location?

Old 10-21-05, 08:18 AM
matt slater
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ventilation calc. and location?

Hello. I Have Completed An Exhaustive Search On Ventilation Information And Have Consulted With Three Local Florida Roofers. The Roofers Are All Over The Place On How Much Ventilation I Need And None Bothered To Tell Me To Close Off The Three Gable Vents Which I Know I Need To Do Now..

I Have A Few Questions About Proper Calculations And Ridge Vent Locations. First, My Home Is A 1967 One Story Rancher With A Gabled Roof, 2800+ Sq. Ft. Incl Garage Attic Hips..

Do I Go By The 300 Nfva Code Or The 150?

At The 150 Level, It Calls For Minimum Of 75 Lin Ft. Exhaust. My Total Ridge Is 140' (65' Across The Main House And Another 37' On The Back Rear Over The Bed Rooms And Another 22' Over The Garage And Kitchen In The Front.

How Should I Separate The Amount Of Vent That Is Cut In? 45' Across Main, 15' Rear And 10' Across Garage? Should It Be Centered Or Near The Outer Edge? Should I Increase Beyond The 75' Recommended If I Match The Intakes By Adding More Soffit Vents? Not Sure How Much Is Overkill?

I Also Have A Metal Box Fan Blowing Air From The Garage Into An Old Attic Access Door Every Few Hours To Increase Circulation. With The New Ridge Vents Replacing The Three Box Vents And Capped Off Gable Vents,

Should I Continue To Use?

I Also Just Had Insulation Blown In At R30 Levels And Do Not Want To Distrupt The Coverage In My Attempt To Block Off The Gable Vents.

Any Products Or Recommendations On How I Can Block Off From The Outside Of The Vent Without Ruining The Look Of The Vent From The Outside?
Old 10-27-05, 04:51 PM
Join Date: Jan 2004
Location: Park City, UT
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The IRC requires 1:300 min venting ratio. Ridge and soffet vents should be equal. I'm nor sure on the other stuff. Why would you block the gable vents? I know that the ridge vent guys don't like any other vent types in the system. For me, galble vent have always worked fine except for vaulted ceilings.

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