As of July 1, 2019, All Automatic Garage Door Openers Must Have a Battery Back Up (CA)SB 969, Dodd. Automatic garage door openers: backup batteries. Existing law requires an automatic garage door opener that is manufactured for sale, purchased, sold, offered for sale, or installed in a residence to comply with specified safety requirements, including that the automatic garage door opener have an automatic reverse safety device. This bill, beginning July 1, 2019, would also require an automatic garage door opener that is manufactured for sale, sold, offered for sale, or installed in a residence to have a battery backup function that is designed to operate when activated because of an electrical outage. The bill would make a violation of those provisions subject to a civil penalty of $1,000. The bill would, on and after July 1, 2019, prohibit a replacement residential garage door from being installed in a manner that connects the door to an existing garage door opener that does not meet the requirements of these provisions. |
Air Quality in the Home
Air Quality in the Home
by Nick Gromicko, Rob London and Kenton Shepard
Indoor air quality is generally worse than most people believe, but there are things you can do about it.
Some Quick Facts:
- Indoor air quality can be worse than that of outdoor air.
- Problems can arise from moisture, insects, pets, appliances, radon, materials used in household products and furnishings, smoke, and other sources.
- Effects range from minor annoyances to major health risks.
- Remedies include ventilation, cleaning, moisture control, inspections, and following manufacturers’ directions when using appliances and products.
Research has shown that the quality of indoor air can be worse than that of outdoor air. Many homes are built or remodeled more tightly, without regard to the factors that assure fresh and healthy indoor air. Our homes today contain many furnishings, appliances and products that can affect indoor air quality.
Signs of indoor air quality problems include:
- unusual and noticeable odors;
- stale or stuffy air;
- a noticeable lack of air movement;
- dirty or faulty central heating or air-conditioning equipment;
- damaged flue pipes and chimneys;
- unvented combustion air sources for fossil-fuel appliances;
- excessive humidity;
- the presence of molds and mildew;
- adverse health reaction after remodeling, weatherizing, bringing in new furniture, using household and hobby products, and moving into a new home; and
- feeling noticeably healthier outside.
Common Sources of Air Quality Problems
Poor indoor air quality can arise from many sources. At least some of the following contaminants can be found in almost any home:
- moisture and biological pollutants, such as molds, mildew, dust mites, animal dander, and cockroaches;
- high humidity levels, inadequate ventilation, and poorly maintained humidifiers and air conditioners;
- combustion products, including carbon monoxide, from unvented fossil-fuel space heaters, unvented gas stoves and ovens, and back-drafting from furnaces and water heaters;
- formaldehyde from durable-press draperies and other textiles, particleboard products, such as cabinets and furniture framing, and adhesives;
- radon, which is a radioactive gas from the soil and rock beneath and around the home’s foundation, groundwater wells, and some building materials;
- household products and furnishings, such as paints, solvents, air fresheners, hobby supplies, dry-cleaned clothing, aerosol sprays, adhesives, and fabric additives used in carpeting and furniture, which can release volatile organic compounds (VOCs);
- asbestos, which is found in most homes more than 20 years old. Sources include deteriorating, damaged and disturbed pipe insulation, fire retardant, acoustical material (such as ceiling tiles) and floor tiles;
- lead from lead-based paint dust, which is created when removing paint by sanding, scraping and burning;
- particulates from dust and pollen, fireplaces, wood stoves, kerosene heaters and unvented gas space heaters; and
- tobacco smoke, which produces particulates, combustion products and formaldehyde.
Remedies to Indoor Air Quality Problems
Living Areas
Paneling, pressed-wood furniture, and cabinetry may release formaldehyde gas.
Remedy: Ask about formaldehyde content before buying furniture and cabinets. Some types of pressed-wood products, such as those with phenol resin, emit less formaldehyde. Also, products coated with polyurethane or laminates may reduce formaldehyde emissions. After installation, open windows. Maintain moderate temperature and humidity.
Biological pollutants can grow on water-damaged carpet. New carpet can release organic gases.
Remedy: Promptly clean and dry water-damaged carpet, or remove it altogether. If adhesives are needed, ask for low-emitting ones. During installation, open doors and windows, and use window fans or room air conditioners. Vacuum regularly. Consider area rugs instead of wall-to-wall carpet. Rugs are easier to remove and clean, and the floor underneath can also be cleaned.
Some floor tiles contain asbestos.
Remedy: Periodically inspect for damage or deterioration. Do not cut, rip, sand or remove any asbestos-containing materials. If you plan to make changes that might disturb the asbestos, or if materials are more than slightly damaged, contact a professional for repair or removal. Call your local or state health department or the Environmental Protection Agency.
Moisture encourages biological pollutants including allergens, such as mold, mildew, dust mites and cockroaches.
Remedy: If possible, eliminate moisture sources. Install and use exhaust fans. Use a dehumidifier, if necessary. Remove molds and mildew by cleaning with a solution of chlorine bleach (1 cup bleach to 1 gallon water). Maintain fresh air with natural and mechanical air circulation.
Your fireplace can be a source of carbon monoxide and combustion pollutants.
Remedy: Open the flue when using the fireplace. Have the flue and chimney inspected annually for exhaust back-drafting, flue obstructions, cracks, excess creosote, and other damage. Install smoke and carbon monoxide detectors.
An air conditioner can be a source of biological allergens.
Remedy: If there is a water tray, empty and clean it often. Follow all service and maintenance procedures, including changing the filter.
Gas and kerosene space heaters can release carbon monoxide and combustion pollutants.
Remedy: Never use unvented kerosene or gas space heaters. In the room where the heater is located, provide fresh air by opening a door to the rest of the house, turning on an exhaust fan, and slightly opening a window.
Tobacco smoke contains harmful combustion and particulate pollutants, including carbon monoxide and combustion byproducts.
Remedy: Do not smoke in your home or permit others to do so, especially near children. If smoking cannot be avoided indoors, open windows and use exhaust fans.
New draperies may be treated with a formaldehyde-based finish and emit odors for a short time.
Remedy: Before hanging, air draperies to ventilate odors. After hanging, ventilate the area. Maintain moderate temperature and humidity.
Paint manufactured before l978 may contain lead.
Remedy: Leave lead-based paint undisturbed if it is in good condition. Before removing paint, test for lead. Do-it-yourself lead test kits are available from hardware and building supply stores. Do not sand, burn off or remove lead-based paint yourself. Hire a person with special training to correct lead-based paint problems. For more information, call 1-800-LEAD-FYI.
Many animals create airborne allergens, such as dander, hair, feathers and skin.
Remedy: Keep pets outdoors as much as possible. Clean the entire house regularly. Deep-clean areas where pets are permitted. Bathe pets regularly.
Biological allergens caused by dust mites can trigger asthma.
Remedy: Clean and vacuum regularly. Wash bedding in water hotter than 130 degrees F. Use more hard-surface finishes; they are less likely to attract and hold dust mites.
Kitchen
Unhealthy and irritating vapors may be released from chemicals in household cleaners and similar products. Remedy: Select nonaerosol and non-toxic products. Use, apply, store and dispose of them according to manufacturers’ directions. If products are concentrated, label the storage container with dilution instructions. Use up a product completely before discarding its container.
Pressed-wood cabinets can be a source of formaldehyde vapor.
Remedy: Maintain moderate temperatures (80 degrees maximum) and humidity (about 45%). When purchasing new cabinets, select solid wood or metal cabinets, or those made with phenol resin; they emit less formaldehyde. Ventilate well after installation.
Unvented gas stoves and ranges are sources of carbon monoxide and combustion byproducts.
Remedy: Keep appliance burners clean. Have burners periodically adjusted (blue-flame tip, not yellow). Install and use an exhaust fan. Never use a gas range or stove to heat your home.
Bathroom
Organic gases are released from chemicals in some personal care products, such as deodorant, hair spray, shampoo, toner, nail polish and perfumes.
Remedy: Select odor-free or low odor-producing products. Select nonaerosol varieties. Open a window, or use an exhaust fan. Follow manufacturers’ directions when using the product and disposing of containers.
Air fresheners can release organic gases.
Remedy: Open a window or use the exhaust fan. Follow manufacturers’ directions. Select natural products.
Bedroom
Humidifiers and cold-mist vaporizers can encourage biological allergens, including mold, mildew and cockroaches, that can trigger asthma, and encourage the spread of viruses and the growth of bacteria.
Remedy: Use and clean these appliances according to manufacturers’ directions. Refill daily with fresh water.
Moth repellents often contain the pesticide paradichlorobenzene.
Remedy: Avoid breathing vapors. Place them in tightly sealed trunks or other containers. Store separately, away from living areas.
Chemicals used in the dry-cleaning process release organic gases.
Remedy: Bring any odors to the attention of your dry cleaner. Try to air out dry-cleaned goods before bringing them indoors. Seek alternatives to dry cleaning, such as hand washing items. Consider using green dry cleaners who use newer, non-toxic solvents and methods to clean garments.
Utility Room
Unvented gas clothes dryers produce carbon monoxide and combustion byproducts and can be a fire hazard. Remedy: Regularly dispose of lint around and under the dryer. Provide air for gas units. Vent the dryer directly to the outdoors. Clean the lint trap, vent and ductwork regularly.
Gas and oil furnaces and boilers, and gas water heaters can produce air-quality problems which include back-drafting of carbon monoxide and combustion pollutants.
Remedy: Have your heating system and water heater, including gas piping and venting, inspected every year.
Asbestos pipe wrap and furnace insulation can release asbestos fibers into the air.
Remedy: Periodically check for damage and deterioration. Do not cut, rip, sand or remove any asbestos-containing materials. If you plan to make changes that might disturb the asbestos, or if materials are more than slightly damaged, contact a professional for repair or removal.
Basement
Ground moisture encourages biological allergens, including mold and mildew.
Remedy: Inspect for condensation on walls, standing water on the floor, and sewage leaks. To keep the basement dry, prevent outside water from entering indoors by installing roof gutters and downspouts, by not watering close to the foundation, by grading soil away from the home, and by applying waterproofing sealants to the basement’s interior walls. To prevent the accumulation of standing water, consider installing a sump pump. If sewage is the source of water intrusion, have drains professionally cleaned. If moisture has no obvious source, install an exhaust fan controlled by humidity levels. Remove mold and mildew. Regularly clean and disinfect the basement floor drain.
Radon is an invisible, radioactive gas which poses the risk of lung cancer.
Remedy: Test your home for radon. Do-it-yourself kits are inexpensive and easy to use. Have an experienced radon contractor mitigate your home if your radon level is 4 picocuries per liter (pCi/L) or higher.
Chemicals in hobby products, such as solvents, paint, glue and epoxy, release organic gases. Remedy: Follow manufacturers’ directions for use, ventilation, application, clean-up, and container storage and disposal. Use outdoors when possible. When using indoors, open a window or use an exhaust fan. Re-seal containers tightly. Clean tools outside or in a well-ventilated area.
Garage
Car and small engine exhaust are sources of carbon monoxide and combustion byproducts.
Remedy: Never leave vehicles, lawn mowers, snowmobiles, etc., running in the garage.
Paint, solvent and cleaning supplies may release harmful vapors.
Remedy: Provide ventilation when using them. Follow manufacturers’ directions. Buy only as much as you need. If the products contain methylene chloride, such as paint strippers, use them outdoors. Re-seal containers well. Keep products in their original, labeled containers. Clean brushes and other materials outside. Opt for non-toxic green products whenever possible.
Pesticides and fertilizers used in the yard and garden may be toxic.
Remedy: Use non-chemical methods whenever possible. Follow manufacturers’ directions for mixing, applying and storing. Wear protective clothing. Mix or dilute these products outdoors. Provide ventilation when using them indoors. Store them outside of the home in their original, labeled containers. After using the product, remove your shoes and clean your hands and clothing to avoid bringing the chemicals into your home.
Smoke and Carbon Monoxide Detectors
- Install a smoke detector in each bedroom or in the adjacent hallway.
- If you have gas or other fossil-fuel appliances in the house, install carbon monoxide detectors in these locations.
- Combination smoke and carbon monoxide detectors are available.
- Check the batteries frequently, at least annually.
Amount of Ventilation
If too little outdoor air enters a home, pollutants can accumulate to levels that can pose health and comfort problems. Unless they are built with a special mechanical means of ventilation, homes that are designed and constructed to minimize the amount of outdoor air that can “leak” into and out of the home may have higher pollutant levels than other homes. However, because some weather conditions can drastically reduce the amount of outdoor air that enters a home, pollutants can build up even in homes that are normally considered “leaky.”
How Does Outdoor Air Enter a House?
Outdoor air enters and leaves a house by infiltration, natural ventilation and mechanical ventilation. In a process known as infiltration, outdoor air flows into the house through openings, joints and cracks in walls, floors and ceilings, and around windows and doors. In natural ventilation, air moves through opened windows and doors. Air movement associated with infiltration and natural ventilation is caused by air-temperature differences between the indoors and outdoors, and by wind. Finally, there are a number of mechanical ventilation devices, from outdoor-vented fans that intermittently remove air from a single room, such as the bathroom and kitchen, to air-handling systems that use fans and ductwork to continuously remove indoor air and distribute filtered and conditioned outdoor air to strategic points throughout the house. The rate at which outdoor air replaces indoor air is described as the air-exchange rate. When there is little infiltration, natural ventilation or mechanical ventilation, the air-exchange rate is low and pollutant levels can increase.
Indoor Air Pollution and Health
Health effects from indoor air pollutants may be experienced soon after exposure or, possibly years later.
Immediate Effects
Immediate effects may show up after a single exposure, or it may take repeated exposures. These include irritation of the eyes, nose and throat, headaches, dizziness and fatigue. Such immediate effects are usually short-term and treatable. Sometimes, the treatment is simply eliminating the person’s exposure to the source of the pollution, if it can be identified. Symptoms of some diseases, including asthma, hypersensitivity pneumonitis, and humidifier fever, may also show up soon after exposure to some indoor air pollutants.
The likelihood of immediate reactions to indoor air pollutants depends on several factors. Age and pre-existing medical conditions are two important influences. In other cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person. Some people can become sensitized to biological pollutants after repeated exposures, and it appears that some people can become sensitized to chemical pollutants, as well.
Certain immediate effects are similar to those from colds and other viral diseases, so it is often difficult to determine if the symptoms are a result of exposure to indoor air pollution. For this reason, it is important to pay attention to the time and place that symptoms occur. If the symptoms fade or go away when a person is away from home, for example, an effort should be made to identify indoor air sources that may be possible causes. Some effects may be made worse by an inadequate supply of outdoor air, or from the heating, cooling or humidity conditions prevalent in the home.
Long-Term Effects
Other health effects may show up years after exposure has occurred, or only after long or repeated periods of exposure. These effects, which include some respiratory diseases, heart disease and cancer, can be severely debilitating or fatal. It is prudent to try to improve the indoor air quality in your home even if symptoms are not noticeable.
While pollutants commonly found in indoor air are responsible for many harmful effects, there is considerable uncertainty about what concentrations or periods of exposure are necessary to produce specific health problems. People also react very differently to exposure to indoor air pollutants. Further research is needed to better understand which health effects occur after exposure to the average pollutant concentrations found in homes, and which occur from the higher concentrations over short periods of time.
In summary, indoor air contaminants can be a source of ill health. Hire an InterNACHI inspector trained in air quality to perform your next home inspection.
Rodent Inspection
Rodent Inspection
by Nick Gromicko and Elise London

- hantavirus pulmonary syndrome;
- hemorrhagic fever with renal; syndrome;
- Lassa fever;
- leptospirosis;
- lymphocytic chorio-meningitis;
- plague;
- rat-bite fever;
- salmonellosis;
- South American arenaviruses; and
- tularemia.
- babesiosis;
- Colorado tick fever;
- human granulocytic anaplasmosis;
- lyme disease;
- murine typhus;
- scrub typhus;
- rickettsialpox;
- relapsing fever; and
- Rocky Mountain spotted fever.
Rodents also pose a danger to the integrity of the structures they inhabit. They have strong teeth and they may chew through structures to gain access to food sources. The best method for preventing exposure to rodents is to prevent rodent infestation in the first place, according to the Centers for Disease Control (CDC) and the U.S. Environmental Protection Agency (EPA).
- chewing or clawing sounds that come from inside or outside a home. Noises may even come from the roof, as tree-dwelling rodents may try to gain access to a home from above the living space;
- stale smells coming from hidden areas;
- evidence of structural damage that can provide entry points into the home;
- evidence of gnawing and chewing on food packaging;
- nesting material found in small piles, such as shredded paper, fabric or dried plant matter; and
- rodent droppings anywhere in the home, especially near food packages in drawers and cupboards, and under the sink.
- Keep food in thick plastic or metal containers with tight-fitting lids.
- Clean up spilled food right away, and wash dishes and cooking utensils soon after use.
- Keep outside cooking areas and grills clean.
- Always put pet food away after use and do not leave pets’ food or water bowls out overnight.
- Keep bird feeders away from the house. Utilize squirrel guards to limit access to the feeder by squirrels and other rodents.
- Use thick plastic or metal garbage cans with tight-fitting lids.
- Keep compost bins as far away from the house as possible.
- Dispose of trash and garbage on a frequent and regular basis, and eliminate clutter in and around the property to discourage nesting.
- inside, under and behind kitchen cabinets, refrigerators and stoves;
- inside closets near the floor’s corners;
- around the fireplace;
- around doors;
- around plumbing pipes under sinks and washing machines;
- around the piping for hot water heaters and furnaces;
- around floor vents and dryer vents;
- inside the attic;
- in the basement or crawlspace;
- near the basement and laundry room floor drains; and
- between the floor and wall juncture.
- in the roof among the rafters, gables and eaves;
- around windows;
- around doors;
- around the foundation;
- near attic vents and crawlspace vents;
- under doors; and
- around holes for electrical, plumbing, cable and gas lines.

- lethal traps, such as snap traps, that are designed to trap and kill rodents;
- live traps, such as cage-type traps, that capture rodents alive and unharmed, requiring that the rodents then be released or killed; and
- glue boards, which are low-cost devices that use sticky substances to trap rodents, requiring a further decision regarding disposal, since such traps are not lethal.
- baits, which combine rodenticides with food to attract rodents. They may be formulated as blocks or paste and may be enclosed in a bait station;
- tracking powders, which are rodenticides combined with a powdery material. The powder sticks to the rodents’ feet and fur and is swallowed when the animals groom themselves. After consuming the chemical poison contained in the bait or tracking powder, the rodents die. Some rodenticides (including tracking powders) may be legally applied only by certified pesticide applicators because they may pose a risk to human health.
- Traps and baits should be placed in areas where children and pets cannot reach them.
- Products should be used according to the label’s directions and precautions.
- Only traps that are appropriate to the type and size of the targeted rodent should be used.
- Glue boards should be placed in dry, dust-free areas, as moisture and dust will reduce their effectiveness.
It is advisable to contact a professional exterminator to deal with more severe infestations, since rodents reproduce constantly and quickly.
In summary, rodent infestation poses a serious risk to human health, and extreme caution must be taken when eliminating the problem.
Knob-and-Tube Wiring
Knob-and-Tube Wiring
InterNACHI inspectors should always disclaim knob-and-tube wiring during their inspections.
Facts About Knob-and-Tube Wiring:
- It is not inherently dangerous. The dangers from this system arise from its age, improper modifications, and situations where building insulation envelops the wires.
- It has no ground wire and thus cannot service any three-pronged appliances.
- While it is considered obsolete, there is no code that requires its complete removal.
- It is treated differently in different jurisdictions. In some areas, it must be removed at all accessible locations, while others merely require that it not be installed in new construction. Inspectors should be sure to know the codes in the jurisdictions in which they operate.
- It is not permitted in any new construction.
How Knob-and-Tube Wiring Works:
K&T wiring consists of insulated copper conductors passing through lumber framing drill-holes via protective porcelain insulating tubes. They are supported along their length by nailed-down porcelain knobs. Where wires enter a wiring device, such as a lamp or switch, or were pulled into a wall, they are protected by flexible cloth or rubber insulation called “loom.”
Advantages of Knob-and-Tube Wiring:
- K&T wiring has a higher ampacity than wiring systems of the same gauge. The reason for this is that the hot and neutral wires are separated from one another, usually by 4 to 6 inches, which allows the wires to readily dissipate heat into free air.
- K&T wires are less likely than Romex cables to be punctured by nails because K&T wires are held away from the framing.
- The porcelain components have an almost unlimited lifespan.
- The original installation of knob-and-tube wiring is often superior to that of modern Romex wiring. K&T wiring installation requires more skill to install than Romex and, for this reason, unskilled people rarely ever installed it.
Problems Associated with K&T Wiring:
- Unsafe modifications are far more common with K&T wiring than they are with Romex and other modern wiring systems. Part of the reason for this is that K&T is so old that more opportunity has existed for improper modifications.
- The insulation that envelopes the wiring is a fire hazard.
- It tends to stretch and sag over time.
- It lacks a grounding conductor. Grounding conductors reduce the chance of electrical fire and damage to sensitive equipment.
- In older systems, wiring is insulated with varnish and fiber materials that are susceptible to deterioration.
Compared with modern wiring insulation, K&T wiring is less resistant to damage. K&T wiring insulated with cambric and asbestos is not rated for moisture exposure. Older systems contained insulation with additives that may oxidize copper wire. Bending the wires may cause insulation to crack and peel away.
K&T wiring is often spliced with modern wiring incorrectly by amateurs. This is perhaps due to the ease by which K&T wiring is accessed.
Building Insulation:
K&T wiring is designed to dissipate heat into free air, and insulation will disturb this process. Insulation around K&T wires will cause heat to build up, and this creates a fire hazard. The 2008 National Electrical Code (NEC) requires that this wiring system not be covered by insulation. Specifically, it states that this wiring system should not be in…
hollow spaces of walls, ceilings and attics where such spaces are insulated by loose, rolled or foamed-in-place insulating material that envelops the conductors.
Local jurisdictions may or may not adopt the NEC’s requirement. The California Electrical Code, for instance, allows insulation to be in contact with knob-and-tube wiring, provided that certain conditions are met, such as, but not limited to, the following:
- A licensed electrical contractor must certify that the system is safe.
- The certification must be filed with the local building department.
- Accessible areas where insulation covers the wiring must be posted with a warning sign. In some areas, this sign must be in Spanish and English.
- The insulation must be non-combustible and non-conductive.
- Normal requirements for insulation must be met.
Modifications:
- Many homeowners adapted to the inadequate amperage of K&T wiring by installing fuses with resistances that were too high for the wiring. The result of this modification is that the fuses would not blow as often and the wiring would suffer heat damage due to excessive amperage loads.
- It is not uncommon for inspectors to find connections wrapped with masking tape or Scotch tape instead of electrical tape.
K&T Wiring and Insurance:
Many insurance companies refuse to insure houses that have knob-and-tube wiring due to the risk of fire. Exceptions are sometimes made for houses where an electrical contractor has deemed the system to be safe.
Advice for those with K&T wiring:
- Have the system evaluated by a qualified electrician. Only an expert can confirm that the system was installed and modified correctly.
- Do not run an excessive amount of appliances in the home, as this can cause a fire.
- Where the wiring is brittle or cracked, it should be replaced. Proper maintenance is crucial.
- K&T wiring should not be used in kitchens, bathrooms, laundry rooms or outdoors. Wiring must be grounded in order to be used safely in these locations.
- Rewiring a house can take weeks and cost thousands of dollars, but unsafe wiring can cause fires, complicate estate transactions, and make insurers skittish.
- Homeowners should carefully consider their options before deciding whether to rewire their house.
- The homeowner or an electrician should carefully remove any insulation that is found surrounding K&T wires.
- Prospective home buyers should get an estimate of the cost of replacing K&T wiring. They can use this amount to negotiate a cheaper price for the house.
In summary, knob-and-tube wiring is likely to be a safety hazard due to improper modifications and the addition of building insulation. Inspectors need to be wary of this old system and be prepared to inform their clients about its potential dangers.
Attic Ventilation
Attic Ventilation
by Nick Gromicko and Rob London
Perhaps the most misunderstood element of home maintenance is attic ventilation. Most people feel gable vents are adequate. They also believe it’s a good idea to close them off during the winter to save heat. And many home owners believe the soffits should be covered with insulation. They feel that seeing light in the attic is a bad idea. “It will let in insects,” is something I hear often. All of these beliefs are wrong dew point temperature and condensation occurs. The dew point is always a temperature. It is the point at which water vapor changes state and becomes a liquid and it is always contingent upon two variables—temperature and humidity.
You now have a wet attic. There are some obvious telltale signs that the home has a moisture problem. Rust forms on nails at the underside of the roof deck. There will also be stains on the floor of the attic from the nails dripping. When I was in the roofing business, home owners would swear this was evidence that “every nail in the attic was leaking.” The stains are the result of the moisture dripping off the nails. You may actually see small icicles hanging off the nails in winter. These stains are the result of excess moisture in the attic. A ridge vent will surely help, but if you have these stains, you have to take a look at moisture sources in the house.
Venting is not enough. Dealing with the excess moisture is often recommended. In reality, most homes are about 70 degrees in the winter, and attics are much colder than 47 degrees. If the air is cold and moving, the water vapor continues to move with the cold air and vents out through the ridge vent. Now if you close off the vents in the attic to save the heat that is now worthless, you trap the moisture in the attic and rot out your attic. You want nice even-balanced, continuously-working ventilation to carry out the moisture. It should be working round the clock and not running off electricity. Continuous soffit and ridge venting will give you the best defense against moisture damage in your attic. Keep in mind, there are other variables with attic moisture. If the home has more moisture than the system can vent out, you may still have moisture accumulate in the attic. A humidifier or a wet basement or crawl space, are a few examples of conditions that can put too much moisture in the home and create problems. Next, let’s take a look at ventilation in the summer.
We ventilate in the summer to let out heat, AND reduce the surface temperature of the roof. The most efficient form of attic ventilation in my opinion is continuous ridge venting, and continuous soffit venting as stated above. This will allow the most air flow over the underside of the roof. A well ventilated attic can help to keep your roof cooler. Heat is the enemy of your roof. I have recorded temperatures in excess of 160 degrees on the surface of the roof. A well-ventilated attic will help reduce the temperature of the shingles. Studies have shown you can reduce the surface temperature of the roof by 20 degrees by having proper attic ventilation. Another thing that happens with a well ventilated attic is it cools down better at night. The attic builds up heat during the day. If the attic is not properly ventilated the heat just sits there at night. The next morning comes and the attic is already hot. It has a running start on building up heat the next day. If it’s properly ventilated, it will cool at night. This cooling will reduce the heat on the 2nd floor and in the attic.
A well-ventilated attic should be close to the outside air temperature just before dawn in the summer. A poorly ventilated attic stays hot right through the night.
We all are familiar with the concept of heat rising. Warm air is thinner than cold air and therefore lighter. The heated air rises and takes the heat with it. This is a process known as convection. Another form of heat transfer that occurs in the attic is thermal radiation, which results from the sun’s rays bearing down on roof shingles. A lot of this heat raises the temperature of the underside of the roof and the shingles and some of it reflects down into the living area. The radiant heat from the attic raises the temperature of the 2nd floor generally about 5 degrees warmer than the first floor. If the roof is poorly ventilated, the 2nd floor may be 12 to 15 degrees hotter. Studies have shown the attic temperature to be as much as 25 degrees hotter in a poorly ventilated attic compared to a well-ventilated one.
If you add a ridge vent to a home that did not previously have one, it is recommended that all other vents, except for those at the soffits, be closed off. Openings such as those at gable vents and roof fans will allow air to enter the attic in a counter-productive manner and short-change the soffit venting. Rather than the air entering at the eaves, it will enter through the other openings and the attic won’t get the full benefit of the balanced system.
So what is proper attic ventilation? Building codes and shingle manufacturers have accepted a formula of 1/150th of the flat attic space to be an appropriate degree of ventilation. The air flow should be balanced equally between high and low areas, or eave
and ridge as discussed. This translates to about one square inch of ventilation for one square foot of attic space. This formula was adopted during World War II, although not based on scientific study, and remains the present-day standard of the construction industry. But it is not always easily attained. There are hip roofs, roofs with dormers, and a variety of other conditions that can make this formula difficult to achieve. A variety of products are on the market that can address unusual conditions. If you have a home where you don’t have an open and easily ventilated attic, you can do your own research. Air Vent, Inc. makes several products to address specific conditions. Their website is www.airvent.com. Another company that has specific materials for such applications is DCI, Inc. Their phone number is 1-800-622-4455.