Bat Infestation

Bat Infestation

by Nick Gromicko and Kenton Shepard

Bats are nocturnal mammals found in most inhabited places throughout the world. Bat infestation in homes, especially in attics, can be a health hazard, as well as a nuisance, for homeowners.

 

Interesting Facts
  • Due to its high levels of phosphorous and nitrogen, guano (bat feces) is an effective fertilizer and gunpowder ingredient. Guano has been such a critical resource that in 1879, a war between Chile and Bolivia, called the Guano War, was waged over rights to the guano-rich western coastline.
  • Despite how large they appear in flight, bats are remarkably small. Some can fit through openings smaller than ½-inch wide. Even the largest bat – the golden-crowned flying-fox — with a wingspan of up to 5 feet, may weigh as little as 3 pounds.
  • Roughly 20% of all known mammal species are species of bats.
  • Bats are the only mammals capable of sustained flight.
  • Contrary to popular belief, bats are neither rodents nor birds, and they are not blind.
Indications of a household bat infestation:    
  • the accumulation of guano. Bat guano resembles rodent droppings but can be distinguished in several ways:  guano tends to cluster as it piles up beneath the exit of the bats’ roost; guano often has a shiny, speckled appearance due to the ingestion of insect wings; and guano can be easily crushed into smaller fragments, while rodent droppings will not. Of course, it is not safe to touch any animal droppings with unprotected hands;
  • milky white urine stains on windows;
  • stains around entry holes, such as cracks and crevices;
  • mouse-like droppings under eaves and overhangs;
  • stains and odors caused by urine and guano;
  • noises such as squeaking, scratching and crawling in attics and walls shortly before dusk and dawn; andLarge pile of bat guano
  • grease and dirt. Bats often leave smears of grease and dirt from their coats on the entry point to their roost.
Bats and Disease
Rabies

Due to their high mobility and social behavior, bats are often hosts for diseases, such as rabies. Rabies is perhaps the most serious disease transmitted by bats in North America. Most of the human rabies cases in the United States have been caused by the rabies virus from bats. Awareness of the facts about bats and rabies can help homeowners protect themselves, their families, and their pets.

Rabies is a virus that affects the nervous system of humans and other mammals. Once symptoms of the disease develop, it is almost always fatal. Humans contract rabies from animal bites. Some bats have teeth so sharp that a sleeping person may not realize that they have been bitten. It is recommended that those waking up with bats in the bedroom undergo a series of preventative (and sometimes painful and expensive) rabies inoculations. The alternative is to capture the bats (without being bitten) and take them to a laboratory for testing.

Indications that a bat has rabies:

  • The bat is in an unusual place, such as a bedroom or in the lawn. Healthy bats do not rest on the ground.
  • The bat is approachable. Healthy bats are scared of humans and will flee long before they can be approached.
  • The bat is active during the day.
  • The bat appears unable to fly.

For these reasons, rabid bats are often most likely to come into contact with humans.

Histoplasmosis
This respiratory disease, caused by the fungus Histoplasma capsulatum, is transmitted through the inhalation of fungal spores found in bat guano and bird droppings. Although generally not fatal, histoplasmosis can cause flu-like symptoms. For individuals with compromised immune systems, such as those with AIDS, histoplasmosis can be fatal.
Bat Removal
The following instructions for bat removal can be passed on from InterNACHI inspectors to their clients:
  • The entry point for the bats should be identified. Holes as small a human thumb are large enough for some bats to squeeze through. The homeowner can seal off most of these holes with caulk, leaving one hole intact for resident bats to exit at night.
  • The homeowner can then plug this hole at night so that bats cannot return to the house. Alternatively, the homeowner can install a one-way “check-valve” from wire mesh that will allow bats to exit the house but not allow them to return.
  • “Bat houses,” which can be constructed or purchased, can be placed next to the house during bat removal to provide bats with an attractive alternative to the house.
Note:  Bat removal should not take place during the summer (in North America). Baby bats that are unable to fly will not be able to leave the house during the summer months and they will starve to death if adults are not permitted to enter the home. Bat removal during the summer is inhumane and will result in the additional problems posed by decomposing bat carcasses.
In summary, bats can transmit dangerous diseases to humans, and inspectors and homeowners should be wary of bat infestations.
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Barbeque Safety

Barbeque Safety

by Nick Gromicko
With barbeque season already here, homeowners should heed the following safety precautions in order to keep their families and property safe.
  • Propane grills present an enormous fire hazard, as the Consumer Product Safety Commission (CPSC) is aware of more than 500 fires that result annually from their misuse or malfunction. The following precautions are recommended specifically when using propane grills:
    • Store propane tanks outdoors and never near the grill or any other heat source. In addition, never store or transport them in your car’s trunk.
    • Make sure to completely turn off the gas after you have finished, or when you are changing the tank. Even a small gas leak can cause a deadly explosion.
    • Check for damage to a tank before refilling it, and only buy propane from reputable suppliers.
    • Never use a propane barbecue grill on a terrace, balcony or roof, as this is dangerous and illegal.
    • No more than two 20-pound propane tanks are allowed on the property of a one- or two-family home.
    • To inspect for a leak, spray a soapy solution over the connections and watch for bubbles. If you see evidence of a leak, reconnect the components and try again. If bubbles persist, replace the leaking parts before using the grill.
    • Make sure connections are secure before turning on the gas, especially if the grill hasn’t been used in months. The most dangerous time to use a propane grill is at the beginning of the barbeque season.
    • Ignite a propane grill with the lid open, not closed. Propane can accumulate beneath a closed lid and explode.
    • When finished, turn off the gas first, and then the controls. This way, residual gas in the pipe will be used up.
  • Charcoal grills pose a serious poisoning threat due to the venting of carbon monoxide (CO). The CPSC estimates that 20 people die annually from accidentally ingesting CO from charcoal grills.  These grills can also be a potential fire hazard. Follow these precautions when using charcoal grills:
    • Never use a charcoal grill indoors, even if the area is ventilated. CO is colorless and odorless, and you will not know you are in danger until it is too late.
    • Use only barbeque starter fluid to start the grill, and don’t add the fluid to an open flame. It is possible for the flame to follow the fluid’s path back to the container as you’re holding it.
    • Let the fluid soak into the coals for a minute before igniting them to allow explosive vapors to dissipate.
    • Charcoal grills are permitted on terraces and balconies only if there is at least 10 feet of clearance from the building, and a water source immediately nearby, such as a hose (or 4 gallons of water).
    • Be careful not to spill any fluid on yourself, and stand back when igniting the grill. Keep the charcoal lighter fluid container at a safe distance from the grill.
    • When cleaning the grill, dispose of the ashes in a metal container with a tight lid, and add water. Do not remove the ashes until they have fully cooled.
    • Fill the base of the grill with charcoal to a depth of no more than 2 inches.
  • Electric grills are probably safer than propane and charcoal grills, but safety precautions need to be used with them as well. Follow these tips when using electric grills:
    • Do not use lighter fluid or any other combustible materials.
    • When using an extension cord, make sure it is rated for the amperage required by the grill. The cord should be unplugged when not in use, and out of a busy foot path to prevent tripping.
    • As always, follow the manufacturer’s instructions.
Safety Recommendations for General Grill Use
  • Always make sure that the grill is used in a safe place, where kids and pets won’t touch or bump into it. Keep in mind that the grill will still be hot after you finish cooking, and anyone coming into contact with it could be burned.
  • If you use a grill lighter, make sure you don’t leave it lying around where children can reach it. They will quickly learn how to use it.
  • Never leave the grill unattended, as this is generally when accidents happen.
  • Keep a fire extinguisher or garden hose nearby.
  • Ensure that the grill is completely cooled before moving it or placing it back in storage.
  • Ensure that the grill is only used on a flat surface that cannot burn, and well away from any shed, trees or shrubs.
  • Clean out the grease and other debris in the grill periodically. Be sure to look for rust or other signs of deterioration.
  • Don’t wear loose clothing that might catch fire while you’re cooking.
  • Use long-handled barbecue tools and flame-resistant oven mitts.
  • Keep alcoholic beverages away from the grill; they are flammable!
In summary, homeowners should exercise caution when using any kind of grill, as they can harm life and property in numerous ways.
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Backdrafting

Backdrafting

by Nick Gromicko and Kenton Shepard

Backdrafting is the reverse flow of gas in the flues of fuel-fired appliances that results in the intrusion of combustion byproducts into the living space. Many fuel-fired water heaters and boilers use household air and lack an induced draft, which makes them especially vulnerable to backdrafting when indoor air pressure becomes unusually low. Inspectors should try to spot evidence of backdrafting in homes.

How does backdrafting happen?

Fuel-fired water heaters, boilers, wall heaters, and furnaces are designed to exhaust the byproducts of combustion to the outdoors through a flue. These hot gases rise through the flue and exit the home because they are not as dense as indoor air. The pressure differential that allows for the release of combustion gases can be overcome by unusually low indoor air pressure caused by a high rate of expulsion of air into the outdoors through exhaust fans, fireplaces and dryers. When this happens, combustion gases can be sucked back into the house and may potentially harm or kill building occupants. Improperly configured flues or flue blockages can also cause backdrafting.

How can InterNACHI inspectors test for backdrafting?

  • An inspector can release smoke or powder into the draft diverter to see whether it gets sucked into the duct or if it spills back into the room. A smoke pencil or a chemical puffer can be used to safely simulate smoke.
  • An inspector can hold a lighter beside the draft diverter to see whether there is sufficient draft to pull the flame in the direction of the flue.
  • Combustion gases that back-draft into a house may leave a dark residue on the top of the water heater. The presence of soot is an indication of backdrafting, although its absence does not guarantee that backdrafting has not happened.
  • A carbon monoxide analyzer can be used to test for backdrafting of that gas. Inspectors should be properly trained to use these before they attempt to use one during an actual inspection, primarily to avoid false negatives.

    While performing the above-noted tests, it is helpful if inspectors ask their clients to turn on all devices that vent air into the outdoors in order to simulate worst-case conditions. Such devices may be dryers, or bathroom and kitchen fans.

Types of fuel-fired water heaters:

  • Atmospheric DraftMost backdrafting is the result of the characteristics of this type of water heater. Combustion gases rise through the ventilation duct solely by the force of convection, which might not be strong enough to counter the pull from dips in indoor air pressure.
  • Induced Draft
    This system incorporates a fan that creates a controlled draft. The potential for backdrafting is reduced because the induced draft is usually strong enough to overcome any competing pull from an indoor air-pressure drop.
  • Sealed Combustion
    The combustion and venting systems are completely sealed off from household air. Combustion air is drawn in from the outdoors through a pipe that is designed for that purpose. The potential for backdrafting is nearly eliminated because the rate of ventilation is not influenced by indoor air pressure, and the vented gas has no pathway into the home.
  • Water Heater Location
    The installation of fuel-fired water heaters in particular household locations can increase the chances of personal harm caused by backdrafting. The 2006 edition of the International Residential Code (IRC) states the following concerning improper location:

Fuel-fired water heaters shall not be installed in a room used as a storage closet. Water heaters located in a bedroom or bathroom shall be installed in a sealed enclosure so that combustion air will not be taken from the living space.

In summary, inspectors should try to spot evidence of backdrafting.

AFCI Testers

AFCI Testers

by Nick Gromicko and Kenton Shepard
What are AFCIs?
 
Arc-fault circuit interrupters (AFCIs) are special types of electrical receptacles (or outlets) and circuit breakers designed to detect and respond to potentially dangerous electrical arcs in home branch wiring.
What are AFCI testers or indicators?
 
AFCI tester indicators (sometimes called AFCI testers) are portable devices designed to test AFCI functionality. They create waveform patterns similar to those produced by actual arc faults, thereby causing working AFCIs to trip. AFCI indicators are considerably larger and more expensive (by several hundred dollars) than  ground-fault circuit interrupter (GFCI) indicators and are of questionable effectiveness. For these reasons, they are not used as widely as GFCI indicators.
Why are AFCI indicators important?
 
While an AFCI circuit breaker comes with a test button that performs a role similar to a portable AFCI indicator, this button cannot test for arc faults within individual portions of the branch circuit. An AFCI indicator, however, can test any individual receptacle within the branch. InterNACHI inspectors should use AFCI indicators to inspect receptacles observed and deemed to be AFCI-protected.
How do they work?
 
AFCI indicators should be inserted directly into the receptacle. Some AFCI indicators, such as the popular #61-165 model produced by Ideal™, offer a number of testing options. This indicator creates eight to 12 pulses of 106 to 141 amp charges in less than a second which should be recognized by the AFCI as a dangerous arc and cause it to open the circuit that it serves. The indicator can also test for nuisance tripping, the annoying tendency of an AFCI to open its circuit when it detects a safe, shared neutral connection. For this test, it produces a 300mA arc that should not cause the AFCI to trip. Some AFCI indicators conveniently incorporate a GFCI indicator into their design.
AFCI indicators are somewhat larger than GFCI indicators but they are operated in the same way. An inspector simply inserts one into a receptacle and navigates the menu in order to produce the desired electric current. The user will know that the circuit in question has been tripped if the AFCI device loses power. If this occurs following an AFCI test, the AFCI is functioning properly. The user should then go to the electrical panel to reset the AFCI breaker. If the test results in the failure of an AFCI breaker to open the circuit, then a qualified electrician should be contacted.
How effective are they?
 
It is important to understand the distinction between an AFCI indicator and the test button on an AFCI device. The latter produces an actual arc fault and can be relied upon to assess the functionality of the AFCI. An indicator, by contrast, creates waveforms that are not true arcs but are characteristic of them and are thus not a completely reliable measure of an AFCI’s functionality. As a result of this distinction, an indicator might not cause a perfectly functional AFCI to trip. Although commonly called testers, it is more appropriate to refer to them as indicators, despite terminology that often appears in AFCI “tester” user guides.
Underwriters Laboratories, a product-testing organization that develops product standards, requires AFCI indicators to include the following information detailing this limitation in their product manuals:

CAUTION:  AFCIs recognize characteristics unique to arcing, and AFCI indicators produce characteristics that mimic some forms of arcing. Because of this, the indicator may give a false indication that the AFCI is not functioning properly. If this occurs, recheck the operation of the AFCI using the test and reset buttons. The AFCI button test function will demonstrate proper operation.
This caution implies that an AFCI is working properly if the indicator causes it to trip, but the reverse is not necessarily true.  An AFCI that does not trip as a result of an indicator may actually be perfectly fine. The test button on the circuit interrupter can be used to confirm its malfunction in the event that the indicator does not cause it to trip. Manufacturers claim that their AFCI indicators provide a universal method to test AFCIs that are produced by different companies.
In summary, AFCI indicators help ensure that AFCIs are properly monitoring the circuits that they serve for dangerous arc faults. These devices create electrical waveforms characteristic of those produced by an actual arc. As their effectiveness has been debated, they should be viewed as a complement to the test button on an AFCI, rather than a substitute.

 

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Aerogel

Aerogel

by Nick Gromicko
Aerogel is a remarkable insulator
Aerogel is a class of porous, solid materials that exhibits an impressive array of extreme properties. Invented in 1931 and used for decades in scientific applications, aerogel is becoming increasingly feasible as a building insulation, largely due to a decrease in the price of the material.
Aerogel is still prohibitively costly for most homeowners, and the few who can afford it probably don’t know what it is. At expensive properties with environmentally friendly features, however, inspectors should be prepared to encounter the material. Also, the prevalence of aerogel is likely to increase in the coming years as it becomes more affordable and widely known.
 
Physical Properties and Identification
Aerogel holds 15 world records for material properties, a few of which are listed below. Aerogel is:
  • lightweight. It is, in fact, the lowest-density solid on the planet. Some types are composed of more than 99% air, yet they still function as solids;
  • extremely high in surface area. It can have a surface area up to 3,000 square meters per gram, meaning that a cubic inch of aerogel, if flattened out, could cover an entire football field; and
  • strong. It can support up to 4,000 times its own weight. In the picture at right, a 2-gram piece of the material is supporting a 2 grams of aerogel can easily support a brick5-pound brick.

The following qualities will also assist with identification. Aerogel:

  • appears blue due to Rayleigh scattering, the same phenomenon that colors the sky;
  • feels like Styrofoam® to the touch. Although a slight touch will not leave a mark, pressing more firmly will leave a lasting depression or even produce a catastrophic breakdown in the structure, causing it to shatter like glass; and
  • is rigid. Despite its name, it is hard and dry, little resembling the gel from which it was derived.

Performance as an Insulator

Composed almost entirely of gas, which is a poor heat conductor, aerogel can almost nullify the three methods of heat transfer (conduction, convection and radiation). Boasting an R-value of 10 to 30, NASA has used the material to protect astronauts and equipment, such as the Mars Rover, from the extreme cold of space. As compared to conventional insulation material, the R-values of vermiculite, rockwool, fiberglass and cellulose are approximately 2.13, 3.1, 3 and 3.1, respectively. Silica aerogel is especially valuable because silica is also a poor conductor of heat.  A metallic aerogel, on the other hand, would be less useful as an insulator.

Production
Aerogel is derived from gels, which are substances in which solid particles span a liquid medium. The first aerogel was produced from silica gels, although later work involved alumina, chromia, carbon and tin oxide. Through a process called super-critical drying, the liquid Aerogel granules, manufactured by Cabotcomponent of the gel is removed, leaving behind the hollow, solid framework. The resulting aerogel is a porous, ultra-lightweight lattice composed of more than 90% air. Ordinarily, drying of a gel results in its shrinkage and collapse (think of Jell-O left out for a few days), but super-critical drying is performed under intense heat and pressure that preserve the structure of the gel.

Manufacturers offer the material in a variety of forms, such as the granules pictured at right, made by Cabot, which are sometimes used as insulation in skylights. Aspen Aerogel® offers 57-inch wide rolls of the material in 0.2- and 0.4-inch thicknesses, while Thermoblok® comes in 1.5-inch wide strips that are used to cover framing studs and help prevent thermal bridging at a cost of about $1.99 per foot.

 

Safety

Aerogel safety is dependent on the safety of the gel from which it was made; it will be carcinogenic, for instance, if the gel from which it was derived had this quality. Fortunately, silica-based aerogel is not known to be dangerous, although it may irritate skin, mucous membranes, eyes, the respiratory tract, and the digestive system. Aerogel is hydroscopic and extremely dry to the touch, which can, in turn, cause it to dry out unprotected skin. Gloves and goggles are recommended for inspectors and contractors who must handle the material.

Aerogel does not seem to be an environmental threat. Aspen Aerogel’s® website states: “Aerogel blankets do not meet any of the characteristics of a U.S. EPA hazardous waste,” and further notes that scrap aerogel may be disposed of in landfills that are approved to accept industrial waste.
In summary, aerogel is a safe, remarkably effective thermal insulator whose use should become more widespread as it becomes more affordable.
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