Seattle Home Inspector's Blog


Not all "short-circuits" are electrical!

     A while back, in a blog that asked "What is Giovanni Venturi doing in my attic?" I mentioned that combinations of different methods of ventilation can result in poorer or even no ventilation.

For example for the best method of venting attics---Ridge vents in combination with soffit vents---to function properly there should not be any "easier" path of air flow to the ridge.  For example if you have a ridge vent and gable vents, air can move more easily from the gable to ridge than from the soffits to ridge leaving areas of the attic under-ventilated.

      Another poor combination is when there are roof vents in combination with the ridge vent as pictured below.  (The ridge vent is installed in a continuous line and capped by the ridge shingles.)  In this installation it is pretty easy to see how when the ridge vent is drawing air out of the attic the easiest path of air flow is going to be through the roof vents.  Again, this leaves most of the attic under ventilated.ridge vents 








      Where you usually see these systems compromised is when the original roof had one method and when the roof was replaced someone said "hey, lets put this newer/better method of venting in."  But then what do you do with the old roof vent holes?  Obviously you just put the roof vents back insunsmile

Charles Buell 

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Comment balloon 5 commentsCharles Buell • March 24 2008 03:20PM


hhhmmm, Interesting information. I never would have guess the combination of the two would cause a problem.

Sean Allen

Posted by Sean Allen, International Financing Solutions (International Financing Solutions ) about 11 years ago
Charles, I find that duct tape works in instances such as this. I always carry a few rolls in the back of the car just to keep my head from exploding. I also buy pain reliever in the giant economy size bottle at Sam's just to ease the pain. At the end of the day a visit with my old friend Jack Daniels makes it all go away.      8>}
Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) about 11 years ago
Can't you just "kick" them downhill a bit where they should be?
Posted by David Holden, DRH Home Inspection Akron, Ohio Summit (DRH Home Inspection Akron, Ohio Summit County Home Inspector) about 11 years ago
Charlie - I don't think I have ever seen both ridge vents and can vents in the same roof.  That actually creates an under-ventilated attic space ?  Interesting.
Posted by Derek Bauer's, Door to Dreams Home Selling Team (Real Estate One) about 11 years ago

Sean, ventilating attics is pretty interesting stuff.

David, I like the idea, is that what the duct tape is for that Michael is talking about?  What about our COE and not fixing anything?

Derek, the most commone improper combination that I see is gable/ridge.



Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) about 11 years ago