Lon GrossmanPublished ASHI Reporter May 2010
Insulation and attic ventilation are listed together in the ASHI Standards of Practice. Although there is a hot-roof theory, which recommends sealing an attic airtight, overwhelmingly home inspectors satisfy the ventilation requirement of the Standards by inspecting, evaluating and reporting on the basic methods of ventilating attics. In order to do so, they become familiar with soffit and roof vents and how to calculate attic-venting requirements.
The benefits of an appropriate combination of attic ventilation; exhaust fan venting to the exterior and insulation are widely accepted. Benefits include lowering heating and cooling costs; preventing premature failure of the roof and deterioration of floorboards, and lessening susceptibility to ice dams in cold climates and mold in all climates.
In the attic, insulation and venting deserve equal attention. In general, insulation should seal all gaps between and around chimneys, chases, plumbing vents and recessed lights that can be covered with insulation. Lights that can be covered have IC stamped inside. IC stands for “insulation contact.” Those without the IC stamp should have a 3-foot-square wall built around them, creating a box that can be covered with insulation.
For more information about attic insulation, there is a map at www.energystar.gov showing the recommended amounts by geographical area, and I’ve posted an article about adding insulation on my Web site. See “Packing It In” on www.technihouse.com
.Inspecting attic ventilation
Soffit vents and five common attic vents are the basic methods of attic ventilation encountered or recommended by home inspectors. Soffit vents
Most people know hot air rises and cold air falls. Soffit vents are the air intake for moving what otherwise could be stagnant or slow-moving hot air through the attic and out through the roof vents.
If a house has eaves (commonly referred to as overhangs), they should be vented.
The best vents are continuous, running the full length of the eave.
Next are rectangular vents, followed by small 3/4-inch to 3-inch holes spaced along the entire length.
Aluminum and vinyl soffit trim usually has small holes or slots, that provide airflow.
All soffit vents have screening or louvers to keep out birds and insects. However, the screening also restricts the airflow, though not as much as those small openings in the aluminum and vinyl soffit trim.
As a general rule of thumb, you almost never can have enough soffit vents.
Common issues with soffit ventilation include the following:
• None or inadequate vents
• Lack of vents behind aluminum soffit trim (Vents were not cut out; do not exist.)
• Insulation stuffed into the eaves or blown over the vents
• Over-painted vents, which restricts air-flow through the louvers and screens
• Vents obstructed by dust or dirt
• No baffles in the attic
Baffles can be inexpensive cardboard or Styrofoam chutes. Their purpose is to keep the soffit ventilation clear and unobstructed. Baffles are installed between the roof trusses or rafters and are placed over the vents, where the roof slopes down and attaches to the top of the exterior wall. Insulation is placed against the baffle to keep it in place. Ideally, you should see some light from the vent if you look down the baffle between the underside of the roof boards and the baffle.
If a house has few or no eaves, venting is still possible. At least two companies make venting systems for this type of house: Smart Vent® by DCI (800-622-4455, www.dciproducts.com
) and The Inhaler® from Great Northern Building Products (800-258-6245, www.everflovent.com
). Both systems are installed under the shingles along the edge of the roof behind the gutters. They are expensive, but a lot less costly than premature roof failure, ice-dam damage and mold.Attic vent types
The five common types of vents for attics are described below, with special attention given to ridge vents because this method of venting is highly effective when done right, but it causes problems when done incorrectly. 1) Top hat or can vents
are most common in northern states and the Midwest.
2) Ridge vents
are a close second and may become more popular if the best-designed types are used properly.
They should not be installed with any other attic vents and all other vent openings (except soffits) should be closed off. If ridge vents are added and old can, gable, power or other vents are not closed, removed or sealed, the thermal dynamics of the entire attic ventilation system is thrown off, presenting the possibility of mold developing and reducing the life of the roof shingles.
Sometimes, a builder will install gable vents with a ridge vent for aesthetic reasons. The gable vents should be closed off by nailing plywood over them so the ridge vent can function as designed.
To be effective, ridge vents must be installed with an equal or slightly greater amount of soffit ventilation. If installed correctly, they work well with most roofs. The exception is a hip roof, which has four sides to it (unlike a gable roof, with just two sides). Usually, there is not enough ridge length to provide adequate ventilation. Can vents are a better choice for a hip roof.
Well-designed ridge vents have baffles that run the entire length of the vent, both front and back. Those baffles are critical to directing wind upward and sucking more hot/moist air out of the attic.
I have inspected numerous houses in my area that have ridge vents without baffles. It is obvious rain and snow blows into the attic through those vents, causing problems.
Additionally, if there is not an equal or greater amount of soffit vents with a ridge vent, air rain and snow can be pulled into the attic down through the ridge vent, regardless of the vent brand.
3) Gable vents
are louvers with screening that are installed in the gable walls of the attic. They are inexpensive, but the least effective of the common attic vents since they depend on wind direction to vent.
are extremely effective if and when the wind is blowing; otherwise, ventilation is limited. Some brands and older turbines can be noisy.
5) Power vents
work great, but they are mechanical devices and when the motor fails, it is out of sight, out of mind. Also, some types are not equipped to remove humidity from the attic, but this can be corrected by installing a combination thermostat /humidistat to turn it on when the temperature or humidity reaches certain levels. How Much Ventilation is Enough?
Regardless of the method used, there is always a question about whether or not it’s doing the job.
The dominant theory is one free square foot of ventilation for every 150 square feet of attic space (1/150). If there’s a vapor barrier beneath the insulation, it can be 1/300.
Wouldn’t it seem you could cut one-square-foot holes in the roof until you get to 1/150? Of course, it doesn’t work that way.
First, the total equation is based on a 50/50 split between the roof vents and the soffit vents. Second, you can and should over-vent the soffit area, but never over-vent the roof vents without an equal number or greater amount of soffit ventilation.
How do you balance a ridge vent with the correct amount of net-free area intake vents? A general rule of thumb is to measure the length of the ridge vent and multiply by 18. Install the same or greater amount of net-free venting in the soffits. Although it’s necessary to take into account how much air flow is restricted by the screens and louvers on all the vents, most manufacturers help with this calculation by stamping on the vent the amount of ventilation it allows, technically called the “net-free vent area.” See the example provided by Air Vent, Inc. for more help with the calculations.The Hot Roof Theory
Although seldom encountered, there is a theory that it is better to seal an attic than vent it.
For an unvented attic, spray foam insulation, which can be closed- or open-cell, is sprayed onto the entire underside of all the roof boards and rafters. It is sprayed down to the eaves, blocking off any opening where air can get into the attic from the exterior.
Open-cell has an insulation R-value of about R 3.4 per inch. While it is a good insulation, it is not a vapor retarder, which might be important in an attic.
Closed-cell foam provides a higher R-value of approximately 6.6 per inch and also is less permeable than open-cell foam, which is better for colder climates.
Both types of foam are two-part compounds mixed by the installer as it is being sprayed in place. Both begin to expand immediately. That’s a big plus when you’re trying to fill every void.
The foam is perfect for walls, crawlspaces, cathedral ceilings and attics that have furnaces in them.
Most builders, architects and inspectors in the United States subscribe to the cold roof theory rather than the hot roof theory. That’s why we insulate the interior ceilings and walls to keep conditioned air in our living space and ventilate the attic.
Like all projects, if not done properly, there will be problems down the road with the hot roof application. If the foam is not 100 percent complete, even small air leaks can cause extensive rot to the roof boards.
Finally, Dr. Joe Lstiburek, an internationally renowned building and construction expert, stated in a recent ASHI seminar that a totally insulated and sealed attic reduces approximately 10 percent of shingle life.
While current building codes may allow unvented attics, a homeowner should always check with the roof shingle manufacturer before going this route. Some shingle manufacturers may void their warranty.Why Vent?
If clients question the importance of ventilation, we can remind them the average family of four generates two to four gallons of moisture per day just by cooking, breathing, bathing, cleaning and doing laundry. That doesn’t include fish tanks, plants, pets, air-drying laundry and so forth. Some of that moisture rises into the attic as a gas and condenses on the roof boards, causing mold, rot and sub-structure and shingle failure.
It was with good reason ASHI included ventilation in the ASHI Standards of Practice and Code of Ethics and specifically mentioned attics.
---------------------------------------------------------------------How to calculate attic ventilation requirements
According to “Principles of Attic Ventilation” from Air Vent Inc. (800-AIR-VENT, www.airvent.com), all you need are a tape measure, paper and pencil, and it will be as easy as 1,2,3.1. Determine the square footage of attic area to be ventilated. To do that, just multiply the length of the attic (in feet) by its width.
Example: For this and the following calculations, we’ll assume the home has a 40’ by 25’ attic area.
Calculation: 40’x25’= 1,000 square feet of attic area.2. Determine the total net free area required.
Once attic square footage is known, divide by 150 (for the 1/150 ratio). That determines the total amount of net-free area needed to properly ventilate the attic.
Calculation: 1,000 square feet divided by 150 = 6.6 square feet of total net-free area.
3. Determine the amount of intake and exhaust (low and high) net-free area required.
For optimum performance, the attic ventilation system must be balanced with intake and exhaust vents.
This is a simple calculation: just divide the answer from step 2 by 2.
Calculation: 6.6 divided by 2 = 3.3 square feet of intake net-free area and 3.3 square feet of exhaust net-free area.
Playing it Safe in the Cold
by Sandy Bourseau
Published December 2011
“Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds.” That inscription on the James Farley Post Office in New York City often is cited as the U.S. Post Office’s unofficial motto.
Because home inspectors also face weather and time-expectation challenges, they might have a similar unofficial motto, hopefully without the gloom of night. Rain, snow, cold and heat present enough challenges to their personal safety.
Working alone and entering a new situation with each inspection, home inspectors routinely encounter hazards where one wrong step or hurried decision can lead to injury or possibly to illness. Because of the physical demands of the job, even a minor injury can mean no work and loss of income. Faced with the risk of pain and financial loss, the wise home inspector considers what can go wrong and thinks about the consequences if it does.
This is true in any season, but winter presents some unique hazards. In general, home inspectors in the north face the more extreme cold weather, but inspectors in other areas may have to cope with rain-slicked surfaces, sudden storms, high winds and even hypothermia.
Up on the rooftop
No surprise here: Roofs were high on the list when members were interviewed in 2008 for an ASHI Reporter article on safety issues.
When winter storms cover roofs with snow, it’s obvious they cannot be inspected, much less walked on. Equally dangerous, but less obvious, is a roof slick from frost or from rain. When these conditions are present, inspectors stay off the roof and document the conditions in their reports.
Given the widely documented risk of getting on a roof in any weather, some inspectors inspect them from the ground with binoculars or from a ladder, again documenting their methods in their reports.
Getting up there
In winter, inspecting from a ladder presents its own hazards. Ladder safety has been featured repeatedly in the ASHI Reporter, yet not once was the additional challenge of using one in winter mentioned.
Cold weather can create uneven surfaces due to an accumulation of ice and snow on the ground. Uneven ground is one of the worst places you can place a ladder because it creates the potential of the ladder tipping over when you’re climbing it. Another reason you do not want to place your ladder on top of snow or ice is the lack of friction between the ladder and the ground. Ice is slippery.
Ladder stability in wet or slippery conditions is a key consideration and can be greatly improved by a number of factors, such as making an informed initial choice of ladder, by ongoing maintenance and inspection of ladder feet, and through the use of stabilizers. Replacement feet are available in rubber, while a wide range of safety feet, ladder stoppers and ground spikes can provide additional support and help to secure the base.
In general, inspectors are aware when the ladder is set up for use, it must be placed on firm, level ground and without any type of slippery condition present at either the base or top support points.
And they know to wear clean, slip-resistant shoes.
Every day, home inspectors make decisions about their personal health and safety. Whether or not to climb that ladder or get on that roof are among the most important.
Yet, how easy it is to overlook a few wet leaves. Wet leaves are a threat whether on the roof, on shoes or the ground.
Safe on the ground?
Even solid ground presents its own perils when it’s wet or cold outside. Slips and falls often occur during entry or exit from vehicles — a reminder to be particularly careful and hold on to the vehicle for support.
The likelihood of taking a fall on a sidewalk or driveway increases proportionally with the amount of freezing rain and ice.
Joseph Chen, m.d., medical director of the Iowa Spine Research and Rehabilitation Center at UI Hospitals and Clinics, suggests, “Take shorter steps and try to plant your whole foot gently down instead of using the typical heel strike that we use when we’re walking or running.”
Dr. Ronald Grelsamer of New York City’s Mount Sinai Medical Center says, “Balance is key to walking on snow- and ice-covered walks and roads.” He offers the following suggestions:
“Move your feet slightly apart as you walk and bend your knees for better control.
“If the terrain is steep, turn sideways, bend your knees and then walk. Do not cross one foot over the other because that will push you off balance.
“Protect your dominant arm (right if you’re right-handed, left if you are left-handed). Since falls usually occur without warning, you have no time to plan. Make a habit of holding your coat lapel or carrying something in your dominant hand while walking. This leaves the other hand free if you respond instinctively to break your fall. If injury does occur, you at least have your dominant side intact during recovery.
“And if you do feel yourself falling, the best thing you can do is relax and let yourself roll into the fall. Your instinct is to brace your body, but that could mean a more severe injury.”
Biting cold replaces suffocating heat
Although there may be a greater danger of slipping and falling in winter, that’s a year-round hazard for home inspectors. Other hazards are seasonal. While, for now, the danger of suffering from heat exhaustion or heat stroke is past, hypothermia and frostbite become a concern.
Hypothermia occurs most commonly at very cold environmental temperatures, but can occur even at cool temperatures (above 40°F) if a person becomes chilled from rain, sweat or submersion in cold water.
According to the Centers for Disease Control and Prevention (CDCP), when the body begins to lose heat faster than it can be produced, the result is hypothermia, or abnormally low body temperature. Body temperature that is too low affects the brain, making the victim unable to think clearly or move well. This makes hypothermia particularly dangerous because a person may not know it is happening and won’t be able to do anything about it.
People who remain outdoors for long periods are in danger of experiencing hypothermia. For home inspectors, unheated crawl spaces, attics and even homes add to the time spent in the cold weather.
Warning signs include the following:
· confusion/fumbling hands,
· memory loss/slurred speech,
The CDCP suggests the following response if someone appears to be suffering from hypothermia:
Take the person’s temperature. If it is below 95°, the situation is an emergency — get medical attention immediately.
If medical care is not available, begin warming the person, as follows:
· Get the victim into a warm room or shelter.
· If the victim has on any wet clothing, remove it.
· Warm the center of the body first — chest, neck, head and groin — using an electric blanket, if available. Or use skin-to-skin contact under loose, dry layers of blankets, clothing, towels or sheets.
· Warm beverages can help increase the body temperature, but do NOT give alcoholic beverages. Do not try to give beverages to an unconscious person.
· After body temperature has increased, keep the person dry and wrapped in a warm blanket, including the head and neck.
· Get medical attention as soon as possible.
A person with severe hypothermia may be unconscious and may not seem to have a pulse or to be breathing. In this case, handle the victim gently, and get emergency assistance immediately. Even if the victim appears dead, CPR should be provided. CPR should continue while the victim is being warmed, until the victim responds or medical aid becomes available. In some cases, hypothermia victims who appear to be dead can be successfully resuscitated.
Although not life-threatening, frostbite can permanently damage the body, and severe cases can lead to amputation. It is an injury to the body that is caused by freezing. Frostbite causes a loss of feeling and color in affected areas. It most often affects the nose, ears, cheeks, chin, fingers or toes.
At the first signs of redness or pain in any skin area, get out of the cold or protect any exposed skin — frostbite may be beginning. Any of the following signs may indicate frostbite:
· a white or grayish-yellow skin area,
· skin that feels unusually firm or waxy,
A victim is often unaware of frostbite until someone else points it out because the frozen tissues are numb.
If you detect symptoms of frostbite in yourself or others, seek medical care. Because frostbite and hypothermia both result from exposure, first determine whether the victim also shows signs of hypothermia, as described previously. Hypothermia is a more serious medical condition and requires emergency medical assistance.
If (1) there is frostbite but no sign of hypothermia and (2) immediate medical care is not available, proceed as follows:
· Get into a warm room as soon as possible.
· Unless absolutely necessary, do not walk on frostbitten feet or toes — this increases the damage.
· Immerse the affected area in warm — not hot — water (the temperature should be comfortable to the touch for unaffected parts of the body).
· Or, warm the affected area using body heat. For example, the heat of an armpit can be used to warm frostbitten fingers.
· Do not rub the frostbitten area with snow or massage it at all. This can cause more damage.
· Don’t use a heating pad, heat lamp or the heat of a stove, fireplace or radiator for warming. Affected areas are numb and can be easily burned.
These procedures are not substitutes for proper medical care. Hypothermia is a medical emergency and a health care provider should evaluate frostbite.
Even when temperatures are only cool, the wind chill effect can increase the likelihood of problems. As the speed of the wind increases, it carries more heat away from the body. When there are high winds, serious weather-related health problems are more likely. For a Wind Chill Chart (shows the difference between air temperature and perceived temperature and amount of time until frostbite occurs), Wind Chill Calculator and information on the updated Wind Chill Temperature Index, see www.nws.noaa.gov/om/windchill.
Prepare for winter
It is a good idea to take a first aid and emergency resuscitation (CPR) course to prepare for cold-weather health problems. Knowing what to do is an important part of protecting your health and the health of others.
Also, doing something as simple as dressing accordingly can reduce the potential for illness and injuries.
For instance, wear the following:
· a hat,
· a knit mask to cover face and mouth,
· sleeves that are snug at the wrist,
· when possible, mittens (they are warmer than gloves),
· water-resistant coat and shoes, and
· several layers of loose-fitting clothing.
Be sure the outer layer of your clothing is tightly woven, preferably wind-resistant, to reduce body-heat loss caused by wind. Wool, silk, or polypropylene inner layers of clothing will hold more body heat than cotton. Stay dry — wet clothing chills the body rapidly. Excess perspiration will increase heat loss, so remove extra layers of clothing whenever you feel too warm. Also, avoid getting gasoline or alcohol on your skin while de-icing and fueling your car or using a snow blower.
These materials in contact with the skin greatly increase heat loss from the body.
Do not ignore shivering. It’s an important first sign that the body is losing heat. Persistent shivering is a signal to return to your vehicle or some heated environment.
Awareness is the greatest tool in staying safe and well as a home inspector. There’s no way to know how many accidents and illnesses are prevented by being aware of the hazards inspectors face, but don’t take any chances. Take every step with care and stay safe.
What Should I Do if I Get Stranded in Cold Weather?
· Tie a brightly colored cloth to the antenna as a signal to rescuers.
· Move anything you need from the trunk into the passenger area.
· Wrap your entire body, including your head, in extra clothing, blankets or newspapers.
· Stay awake. You will be less vulnerable to cold-related health problems.
· Run the motor (and heater) for about 10 minutes per hour, opening one window slightly to let in air. Make sure that snow is not blocking the exhaust pipe — this will reduce the risk of carbon monoxide poisoning.
· As you sit, keep moving your arms and legs to improve your circulation and stay warmer.
· Do not eat unmelted snow because it will lower your body temperature.
· And, all seasons of the year, be sure someone knows the time the inspection was scheduled, where it is and when you are expected to check in.
Source: The Centers for Disease Control and Prevention
When was the last time you changed the filters in your heating/cooling system? The report for this fuzzy system called for a mold test … could this kill a contract … ummmm, yes? Protect your investment and the health of your family by replacing your filters every 30 days.