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rowdy48 02-27-2009 03:47 PM

roof vents and power vent
A local roofing co replaced two roofs on our block. Both two story homes have the same square footage and floor plan. The position of all vents prior to the work was identical on both homes. Neither power vent has a humidistat

On the first home there were 4 vents ( the small aprox 12 x 12 square vents mounted just below the ridge ) and a power vent. On this home they just replaced the small vents with new and kept the power vent.

On the second home, done about two months later they removed the four small vents and boarded up the holes telling the home owner the small vents were counter productive with the power vent. ( They also charged extra for this service )

Anyone have an opinion on which is proper ?

I think the four small vents should have remained. The houses were built in the 70's and neither has had any humidity problems in the attic..

Hube 02-28-2009 09:41 AM

Not only are roof vents needed but also soffit vents are needed. Air enters into the soffits and then exits out the high vents.
note; You can NEVER have too much ventilation in an attic area as long as there is sufficient(R value) insulation in the attic floor.
Also, if there is adequate ventilation via soffit and ridge vents ,there is no real need for any power venting at all. Save the cost of the fan and the electric power and just let natural air flow circulation do the job.

jdougn 02-28-2009 03:37 PM

Hube is right on all counts. Adequate ridge vents and soffit vents eliminate any need for a power roof vent as long as there is sufficient attic insulation.

The four roof vents let air straight in to the power fan and could easily by-pass areas of the attic that need ventilation. If the attic has inadequate ventilation in the first place from where does the power fan get air?

hth, Doug

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