soffit vents

Old 08-17-01, 08:52 PM
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I need an idea for adding vent to vinyl soffits, the have wooed soffit uder the vinyl.
Old 08-30-01, 09:08 PM
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If your soffit is not perforated or does not have enough perforations, it probably won't do any good.

You need at least 15 sq in per lin foot of air space.
If you do not have a ridge vent then any effects would be minimal.

If you meet the air space specs then install a shingle over ridge vent. Check Cap vents are marginal at best and power fans can't be used in winter when you need them the most to vent moisture.

If you are trying to reduce attic heat in order to reduce a/c costs then you are better off installing a radiant barrier over your existing insulation. You probably have fiber glass and it performs very poorly in attics.

I install a 2 piece material on top off the fiber glass. It is a DIY job if you want to do it. It can cut the a/c run time up to 65%.

Thank you for considering my personal opinion. If you have any further questions about installation of material source, let me know.
Old 09-30-01, 06:16 PM
some help
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Hello rbisys
You need at least 15 sq in per lin foot of air space.
where did you come up with this formula? I have never seen this much air for 1 lin. foot of air space.....Thanks
Old 09-30-01, 07:22 PM
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This is what the manufactuers recommend. A slot 1" wide is usually enough. If you don't have enough draw the ridge vent will draw from one side to the other drawing in rain or snow. Better to have too much instead of not enough.
If you live in a high wind area try to keep the soffit size as close as possible to the mfgr's recommendation.

I take it you're thinking of removing the soffit and cutting holes. Set your circular saw shallow and slot towards the outside of wood soffit. If you cut next to the house you might get turbulance over the insulation near the walls in attic.

If you replace the soffit check with the dealer and see what the sq inch flow per sq foot is. On alum soffit the dimpled type is about 7 1/" sq and the hole type 15 " per square foot material.

The adittional air flow may or may not lower a/c costs depending on your particular situation. The combo of the ridge vent and radiant barrier will make a big change, as I mentioned before. It will also drop attic temps since the fiber glass will not be able to absorb and hold as much heat as before You can DIY the radiant barrier yourself. The type I designed lays on top of the fiber glass between the trusses.

Thank you for considering my opinion.

George H

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