Inadequate Ventilation = Cheating your Sheathing

I recently inspected an older home (pre-1980) in what on the surface, appeared to be in wonderful shape. The roof shingles appeared to be brand new. As I climbed the ladder and pressed down on the roof surface, it felt softer than I was comfortable climbing on. The last thing a homeowner needs is 240 lbs. crashing through the ceiling. The shingles where pliable enough to peel back and reveal a 2” gap between the sheathing and the fascia board.

Home Inspection Blog 1 Roof Inspection

The sheathing was as soft and pliable as the shingles! I checked a few more spots around the roof to see if this problem was consistent, seeing as it was I decided to see if the attic held the answer.

I removed the cover from the attic scuttle hole pushed back the blown-in insulation and climbed in to the safari desert, I mean the  attic.

Home Inspection Blog 1 - Roof Louver


 Feeling on random points of the sheathing to make sure the softness was consistent it became clear what the problem was. There was little to no ventilation. There were gable louvers, a ridge vent and even a turbine. But all where obstructed, as where the two soffits that were supposed to allow fresh air in.

The ventilation system is a system that requires balance. Ideally you want air flow intake through the soffits and preferably one source of an exhaust pathway to let the air out.  The total net free area of the intake vents should match or exceed the total net free area of the exhaust vents for the most optimal performance. Air follows the path of least resistance. If two or more different types of exhaust vents are in place, the secondary exhaust vent interrupts the flow of air and could actually become an intake vent for the primary exhaust vent - leaving large chunks of attic space incorrectly vented.

Home Inspection Blog 1 - Sheathing

Due to this attic’s obstructed ventilation system, the moisture content in the attic began to eat away at the strength of the sheathing leaving the plywood soft, stained, discolored and in need of a complete replacement.



A warning to all homeowners, make sure your attic’s ventilation system is clear and free of debris because a little spring cleaning can save you thousands in roof replacement cost.


Thank you for taking the time to read my blog. If you like what you have read stay tuned for more to come.  For your Home Inspection needs, please contact me for scheduling (614) 657-9807. I am a certified Home Inspector serving Columbus, Ohio and the surrounding areas.