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A prospective customer has a roof with approx.448 sq. inches of roof vent(7 slant back roof vents).He has approx.5,184 sq.inches of soffit vent.That looks like approx.11 times as much intake capacity as output.Will such an arrangement likely cause a “reverse venting “situation?
The roof is 14 years old and shingle condition is about what I would expect for that age of roof.Due to improperly woven valleys,zero valley flashing,zero icegaurd,zero drip edge,and poor chimney flashing the house has numerous leaks.(I guess that’s what happens when you buy a roof from a retailer better known for selling refrigerators and cheap clothes)Could the widespread mold in the attic be at least partially caused by this bizzarre venting arrangement?
BTW the homeowner installed the soffit vents himself a month or so after the roof was installed 14 years ago.Can’t blame the soffit vents on one of americas favorite retailers.
thanks,Stephen
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FWIW, in almost all cases where I see extensive mold in the roof, there's a very damp/wet crawl space.
Bob
*Stephen. Ideally the ridge and soffit net free venting areas (NFVA) should match...be balanced. As the soffit NFVA is reduced, a point is reached where the ridge vent reverses: the windward side becomes an intake and the leeward side becomes an exhaust vent. When the ratio of ridge NFVA to soffit NFVA is 9 to 6 there is little danger of ridge vent reversal until the holes o the soffit vents become clogged with dirt. When the ratio is 9 to 4 or 9 to 3 reversal is highly probable. The exact point at which the imbalance results in ridge vent reversal is unknown. The ridge vent must be driven--fed air--by the soffit vents. An absolute balance is not necessary.A ten to fifteen percent increase in soffit NFVA is acceptable. However, excessive soffit NFVA will cause the air to flow from one soffit vent to the opposite soffit vent,thus mainly bypassing the ridge vent. However, where in the soffit the vents are located is important..if one is to minimise rain, snow or both penetration..GeneL.
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A prospective customer has a roof with approx.448 sq. inches of roof vent(7 slant back roof vents).He has approx.5,184 sq.inches of soffit vent.That looks like approx.11 times as much intake capacity as output.Will such an arrangement likely cause a "reverse venting "situation?
The roof is 14 years old and shingle condition is about what I would expect for that age of roof.Due to improperly woven valleys,zero valley flashing,zero icegaurd,zero drip edge,and poor chimney flashing the house has numerous leaks.(I guess that's what happens when you buy a roof from a retailer better known for selling refrigerators and cheap clothes)Could the widespread mold in the attic be at least partially caused by this bizzarre venting arrangement?
BTW the homeowner installed the soffit vents himself a month or so after the roof was installed 14 years ago.Can't blame the soffit vents on one of americas favorite retailers.
thanks,Stephen