Venting a hip roof
What is the recommended solution on a hip roof, with an existing ridge vent that is not long enough to provide sufficient exhaust? The recommended roof venting is 1 sf per 300 sf of attic floor space, split evenly between ridge and soffit. There is plenty of soffit intake, but due to the shortened length of the ridge resulting from the hip roof design, the ridge vent provides only 65% of the recommended exhaust venting. The roofers I have consulted seem all over the place on this and don’t seem to have sufficient knowledge of building science.
In researching this, it seems that simply adding box vents could cause short circuiting between the box vents and the ridge vent.
– What is the downside risk of leaving the existing setup with insufficient ridge venting?
– Are there solutions other than removing the ridge vent and replacing it with sufficient quantity of box vents?
– Is there a ridge vent that offers up to 65% more venting than the standard 18 square inches/foot?
– Do specialized hip vents (which vent the top 3′ or so of the hip slope) also cause the short circuiting issue?
– There is a second floor over part of the structure, so some portions of the roof end at the second floor walls rather than a ridge. Would installing box vents near the top of the slopes with walls prevent the short circuiting, since those areas are away from the ridge?
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