Does My Attic Have Adequate Ventilation?

Calculate how much you need with simple math
By Paul Bianchina

Remember how hot your attic was when you went up there to check the antenna wire last summer? Remember that ice dam on the roof? Proper attic ventilation can help with both those problems, but how do you know how much you need -- and just as importantly, how much do you already have?

Determining what you need is simple -- all you need is the size of your house and a calculator. Attic ventilation should equal approximately 1 square foot of vent area for every 300 square feet of attic, so figure out roughly how many square feet the footprint of your attic is, and then divide by 300. To ensure effective air movement throughout the attic, the total vent area should be split approximately evenly between high and low vents, so now divide that number by two to get a rough idea of how much low ventilation and how much high ventilation your home needs.
Finally, since vents are measured and sold based on square inches, you'll want to convert from square feet. To do that, take the total amount of ventilation you need in square feet and multiply by 144 to convert it to square inches.

DETERMINING WHAT'S EXISTING

In order to determine how much ventilation you currently have, you need to measure the sizes of the existing vents, and then make a few adjustments in order to figure out exactly how much air is able to actually get through them.

Let's say you have a 12-inch-by-18-inch gable-end vent. That equals an area of 216 square inches (12 x 18), and that's how much ventilation area you would have if you left the hole wide open. However, to prevent animals, insects and rain from getting into your attic, you would need to install a gable-end vent, which has a screen and louvers on it. You have now reduced the amount of area that the air can pass though by the amount of area taken up by the screen, the louvers and the framework of the vent. The remaining open area that the air can actually pass through is called the net free area (NFA), and that is how vents are rated.

If you are purchasing new vents, the NFA should be printed right on the vent itself. If it isn't, or if you are trying to figure out how much vent area you currently have with your existing vents, here are some common vents and their approximate net-free area:

• 7-inch round roof vent: 30 square inches
• 8-inch round roof vent: 40 square inches
• 9-inch round roof vent: 50 square inches
• 12-inch x 18-inch gable vent: 96 square inches
• 3.5-inch x 22.5-inch soffit vent: 40 square inches
• 5.5-inch x 22.5-inch soffit vent: 72 square inches
• Continuous ridge vent: 11 to 16 square inches per linear foot

For other types of vents, you can calculate the NFA using the following formula: Gross vent area / area factor = NFA. The area factor is how much of an adjustment you need to make for the screen and other obstructions, based on the following approximations:

• 1/4-inch screen: area factor = 1.0
• 1/4-inch screen with louvers: area factor = 2.0
• 1/8-inch screen: area factor = 1.25
• 1/8-inch screen with louvers: area factor = 2.25
• Louvers, no screen: area factor = 2.0

So, using that formula, let's say you have a big 12-inch-by-24-inch gable-end vent with 1/8-inch screen and louvers. The gross size of the vent is 288 square inches (12 x 24), and the area factor for 1/8-inch screen with louvers is 2.25. Divide 288 by 2.25, and you can determine that your vent has approximately 128 square inches of net free area.

ADD MORE VENTS AS NEEDED

If, after all this math, you determine that your attic does not have enough ventilation, you need to give some serious thought to adding more.

Separate what you need into high and low, and decide how many of each type of vent you need. Remember that the half and half ratio of high to low is only an approximation -- if you have almost enough low vents and are short on high vents, you can add a little more high-vent area than you need to make up the difference.Hardware stores, home centers and lumberyards all carry a wide variety of vents for different applications. You can install them yourself, or contact a licensed roofing contractor to have it done for you.

Packing Tips

Whether you hire professional movers to pack up your household items or do it yourself, here are some suggestions to make your move go more smoothly:
* Buy high-quality supplies, including moving boxes in a variety of sizes.
* Use packing paper and bubble wrap to protect items from breaking inside boxes.
* Close boxes securely with packing tape and clearly label the contents of each box with bold markers, labels, or stickers.
* Do not pack items that are flammable, corrosive, or explosive, such as gasoline, fireworks, aerosol cans, paints, pesticides, or liquid bleach.
* Hand-carry valuable items such as important documents, jewelry, collections, and family photographs to keep them secure during the move.
* Pack items in a logical order. Top national movers suggest you start with out-of-season items, followed by items you use infrequently. Don't pack the things you need on a daily basis until the last minute.

Jackson Council Decides to Join State Gypsy Moth Program

This article from the Asbury Park Press tells of the 3.5 hour deliberation at last night's Township Council meeting.

The Council decided to join the State's Gypsy moth spraying program for $1 million.

Important Township Meetings This Week

The Township Council will be having a public hearing on the Gypsy Moth debate at its normal meeting on Tuesday, January 22nd. The Caucus Meeting (which is open to the public) begins at 6:30 pm at Town Hall and their Executive Session (closed to the public) will follow immediately then the Business Meeting will immediately follow that.

On Wednesday, January 23rd the Council will hold a Special Open Meeting to hear presentations about the three possible EMS plans (MONOC, Quality Medical Transport & Jackson Police EMS --Click on the links to see a preview of their presentations. None for Quality posted yet) at the Jackson Liberty High School. The meeting starts at 7pm and the Council may vote to act on one of the proposals at this meeting.

Both of these meetings are of high importance to the township and both could have significant impact on property taxes. Homeowners should make every effort to attend these meetings.

My absense

I apologize for my extended absense from this blog.

I have been re-energized to get this blog going and have a re-newed committment to it.

Hopefully, as you stumble across this blog you will find in compelling and add it to your list of places you visit frequently for information about Jackson, NJ.

If you have any questions about the area or the housing market, always feel free to contact me @ mattgen@optonline.net

How to Hire A Chimney Sweep

I received the following information from my friend, Kyle Saker. Kyle runs Complete Inspection Service and is a great resource that I can not recommend any higher.

Anyway, I thought that this is very timely, helpful information that any homeowner with a fireplace should definitely pay attention to:

How to Hire a Chimney Sweep:

The Chimney Safety Institute of America (CSIA) recommends people take a few steps when considering a chimney sweep for an annual inspection and cleaning.

1. How long has the company been in business?

2. Do they offer references?

3. Do they have unresolved complaints with the Better Business Bureau?

4. Do they carry liability insurance to protect your property from accidents?

5. Do the ensure that the sweep is CSIA certified?

There are over 1900 CSIA certified chimney sweeps in North America. To locate on in your area go to http://www.csia.org/ or call (800) 536.0118