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-   -   Could lack of soffit venting increase indoor negative air pressure? (http://www.diychatroom.com/f9/could-lack-soffit-venting-increase-indoor-negative-air-pressure-39827/)

creamaster 03-07-2009 09:32 AM

Could lack of soffit venting increase indoor negative air pressure?
 
My windows are misbehaving with moisture and frosting around the sash and jamb and I think it may have something to do with increased negative indoor air pressure causing air infiltration around the weatherstripping. Indoor RH% is controlled with a dehumidifier and statys around mid 30's. No condensation is present on teh glass protion of any of the windows.

A window technician came out to check the windows that I installed and he said they were installed correctly. I live in Western NY where the winters get cold and at night when the temps dip the frosting is occuring. The windows that are misbehaving are the North and East facing ones. We have a gas forced air furnace and water heater, no fresh air instake. The house is a ranch built in late 60's, cedar sided.

The attic is approx. 1000 sq feet with 4 static roof vents, hooded, approx 1 square foot each. There is 1 square foot of total soffit venting. There is a total of R 38 of insulation in the attic with vapor barrier paper on the insulation. The North side of the roof, only, has frosting on the roofing nail tips where they protrude through the sheating.

The soffit venting I believe may be less than what I should have and I am curious if this will have an increased stack effect on the indoor air and pull more air through the ceiling to allow venting through the roof vents thus causing an increase in the negative air pressure? I opened a basement window cracked 1/8 open and there is a strong breeze blowing in the window quite constantly. Any ideas suggestions?

Thanks

Chemist1961 03-07-2009 01:27 PM

Go here to read up on ventuilation. This is from close to home www.buildingscience.com


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