Replies

1. 
   Guest_ | Jul 30, 1999 09:48pm | #9

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   While on vacation I noticed the soffit vent of a newly-constructed hotel. The vent screen was white, either PVC or aluminum, and spanned the entire width of the soffit, about 24" wide. Until then, every soffit vent screen I had seen was about 3" wide. The panels appeared to snap-in or rest in channels on either side. The vent holes were thousands of tiny slots cut into the material. I would like to know more about this product and who makes it. Would a product like this be useful and cost effective for a residential application? Please enlighten me! Thanks.

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   Guest_ | Jul 26, 1999 07:20am | #1

   *Chris,You can get this type of product in aluminum and vinyl. If you are using one these products to side your house then I would certainly consider this type of soffit vent. If, however, you are using brick or another high end product to side I suggest you consider Hardy Soffit. This product is made from cement and wood fiber. It is fire resistant and takes paint better than wood. You can get extruded PVC screens sized to work with this material. Using these products together produces a very pleasing and very low maintenance result. You can also get Hardy Board siding. Much better than aluminum or vinyl. More money, of course, but you get what you pay for.

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   Guest_ | Jul 27, 1999 01:48am | #2

   *Chris. Read the article Soffit Vents, in Chapter 23 of my book, _Complete_Building_Construction_ 4th Edition, published by Macmillan. I believe after reading this section--and read the entire chapter--you may have seconf thought about using the vinyl soffit vent panels.I'm all for vinyl soffit panels. However, the ones I use are unperforated. If I were to vnetilkate the attic I'd use a continuous double louvered soffit vent such as manufactured by Air Vent, Inc., their model SV202 installed next to the fascia board. the soffit vents must be located as far away from the outside wall as possible. GeneL.

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   Guest_ | Jul 28, 1999 10:54am | #3

   *Gene .. What's wrong with vinyl? I apologize for not having the time at the moment to go hunting for your book, although it does sound like a good future investment. Could you post a brief explanation in this forum. Much appreciated .. Chris

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   Guest_ | Jul 28, 1999 07:35pm | #4

   *Chris. Most of the soffit vents made of vinyl, aluminum, and masonite have either circular holes or slots. Typically, the vinyl soffits have 0.125-inch (1/8) diameter holes spaced 0.5 (1/2) inch on center (oc). A full square foot of these soffit vents would initially provide a Net Free Vent Area (NFVA)of 6 square inches to the ridge vents 9 square inches. If the average soffit is six inches wide, the installed NFVA of these vents is about 3 square inches. As the soffit vent NFVA is reduced, a point is reached where the vents do not feed enough air to the ridge vent and it reverses: the windward side of the vent becomes an intake vent, and the leeward side becomes an exhaust vent.Remmember that a 1-foot wide soffit allows only a 10-inch wide piece of aluminum, vinyl or masonite. This reduces the NFVA to 5 square inches, which may be adequate as long as the vents are not painted, or enough of the holes eventually blocked by dirt to reduce the NFVA to the danger point.When I was Code Enmforcement Officer in Merrimack, New Hampshire, I witnessed water damage and rotting to all the roofs in a 52 house subdivision.The ridge vents, with one exception, were correctly installed. The pegboard (masonite) soffits were less than 5-inches wide and had an NFVA of 0.75 square inches before they were painted. The painting, wind angle, and turbulence arounbd the holes further reduced the NFVA to about ZERO. Even with a full square foot vinyl panel with an NFVA of 12.8square inches per square foot, if the holes are too small, less than 0.0625 inch (1/16)they will clog with dirt, pollen, and so on. They could fail with one year after installation.By the bye, chris. We are not talking theory here. This is all from the real world.I hope this helps. GeneL.

2. 
   Norm_Kerr | Jul 28, 1999 09:49pm | #5

   *Attic Ventilation is a key issue for me.I have been trying to find all I can about attic venting but have so far found my situation is unique (I will look for your book this weekend).I hope that someone can advise me:My house was built in 1903 with the roof partially over the 2nd floor (1 3/4 floor house?) and the soffits are separated from the rest of the attic by the tops of the perimiter walls. Because the roof was just replaced before I moved in (2yrs ago) I have no idea how well this worked, but it has no ventilation provided to the soffits at all.The new roof has a full ridge vent, the attic floor area is about 750 sq ft. The house is located in Ann Arbor, MI. The previous owner had applied fiberglass matt insulation directly to the underside of the roof sheething (no air circulation), which I have removed and used to insulate the attic floor (paper side down).My problem is: how do I decide if this system needs to be changed to avoid future problems?(I have confirmed that the interior of the roof does not become moist (winter or summer) in the exposed parts of the attic). There are no obvious signs of trouble so far (in the new roof or in the surrounding walls) but this lack of venting doesn't sound 'right' per all that I have read in this web site so far...I appreciate any comments that you all might have.

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   Guest_ | Jul 29, 1999 07:59pm | #6

   *Norm. I'm surprised at your comment that "but this lack of venting doesn't sound 'right' per all that I have read in this web site so far..."Not venting attics is one the most hotly debated topics on Breaktime.Yes, there are two camps: those who argue for attic ventilation and those who say that with proper sealing and adequate insulation levels it is unnecessary.are ágin it. In the early 1990s I argued that the first line of defense against ice dams and moisture problems begins in the basement with the sealing of the cellar ceiling.This is also done in the attic. When Carefully and Thoroughly done,and the insulation levels beefed-up with cellulose, the need for attic ventilation is eliminated. GeneL

4. 
   Guest_ | Jul 29, 1999 10:04pm | #7

   *I stand corrected. What I ought to have said is that there is so much conflicting information "out there". In fact, I had ALWAYS heard that ventilation was "good" until I got to FineHomebuilding. The point you make is an excellent one. I look forward to reading your book this weekend. Thanks.

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   Guest_ | Jul 30, 1999 08:17am | #8

   *Congrats Gene! Another sale. Cha-ching!

6. 
   Guest_ | Jul 30, 1999 09:48pm | #10

   *Norm. There is an error in my book on pahe 602. Figure 23-3 is wrong.The wind direction is Perpendicular to the ridge. and in Figure 23-4 the wind direction is parallel to the ridge. JRS. Macmillan is happy with the sales of my book. If only Oprah....GeneL