Inspector's Corner

On the Gulf Home Inspection Services
10 Oct

Backdrafting

Author bwisnewski

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.

10 Oct

AFCI Testers

Author bwisnewski

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.

 

InspectorSeek.com
10 Oct

Aerogel

Author bwisnewski

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.
InspectorSeek.com
10 Oct

Acid Rain

Author bwisnewski

Acid Rain and Inspectors: Buildings at Risk

by Nick Gromicko and Kate Tarasenko
“Acid rain,” like “global warming,” is a phenomenon whose very existence is disputed by some.  In fact, evidence of acid rain has been observed in industrialized cities around the world since the mid-1800s.  “Acid rain” describes the mixture of wet and dry deposits from the atmosphere which contain high amounts of nitric and sulfuric acids that result from both natural and man-made emissions.  Its effects on structures and homes are very real.  Inspectors can learn more about acid rain and its destructive signs on metal and stone components of the exteriors of homes.
Acid rain is formed when the chemical precursors of nitric and sulfuric acids — sulfur dioxide (SO2) and nitrogen oxide (NOx), respectively — combine with natural sources of acidic particles, such as volcanoes and decaying vegetation.  When this mixture reacts with oxygen, water and other chemicals (including pollutants such as carbon dioxide), the result is acid rain, which can be carried by rain, and even snow, frost, fog and mist, which, in turn, runs off into soil and groundwater.
According to the EPA, about two-thirds of all SO2 and one-quarter of the NOx emissions in the atmosphere in the U.S. result from power plants that burn fossil fuels (primarily coal), as well as vehicles and agricultural equipment that rely on gasoline.

It is fair to say that any industrialized region with power plants that burn fossil fuels will show some wear on its surrounding structures from acid rain.  But buildings in arid regions are at greater risk because of dry deposition, in which acidic pollutants are present in gases, smoke and dust, which tend to stick to buildings, cars and other structures.  When it rains or snows, the subsequent wet deposition of nitric and sulfuric acids becomes even more acidic, which then washes into the soil and aquifers.

The more obvious impacts of acid rain can be seen on particular types of stone, such as limestone and marble buildings, monuments, statues and headstones.  The weathering pits and canyons can obliterate the lettering and features of such structures to a brutal degree, depending on the type of stone and other environmental conditions.
Acid rain can also corrode bronze and other metals, such as nickel, zinc, copper, and carbon-steel, as evidenced by streaks and discoloration on bridges and other metal structures, such as many commercial buildings.

Not all buildings or structures suffer the effects of acid rain.  How big of a threat it is can be determined by the chemical makeup and  interactions of a building’s materials.  Limestone and marble, which, historically, were used widely because of their availability and workability by artisans, are especially susceptible because they are composed of calcite, or calcium carbonate, which acidic chemicals can dissolve easily.  To observe this first-hand, drop a piece of blackboard chalk into a glass of vinegar.  Drop another piece of chalk into a glass of water.  The next morning, you’ll see the alarming difference.

Modern buildings tend to use granite, which is composed of silicate minerals, such as quartz and feldspar.  Silicate minerals resist acidic attacks from the atmosphere.  Sandstone, another silica material, is also resistant.  Stainless steel and aluminum tend to hold up better.  But all minerals, including those found in paint and road overlay, are affected, to some degree.

Because of the switchover in the use of certain building materials in the post-Industrial Era, historic buildings, more so than modern ones, tend to show the destructive outcome of acid rain since we first began burning fossil fuels for energy.  London’s Westminster Abbey, the Colosseum in Rome, and India’s Taj Mahal all show signs of degradation brought on by atmospheric nitric and sulfuric acids.
Plant life and wildlife are also affected.  The pH — or alkalinity and acidity — of lake water, for example, tends to re-stabilize and maintain equilibrium when contaminated by acid rain.  However, soil and trees can become irreparably harmed when their pH is disturbed to the extent that their natural abilities to compensate for chemical fluctuations in the environment are thwarted.  Soil contains naturally occurring mercury and aluminum, which are normally poisonous for plant life.  But plants can survive when the nutrient base of the soil remains healthy, giving them a strong buffering capacity.  Acid rain, however, destroys the environmental balance, and these naturally occurring chemical threats suddenly become fatal.  The plants’ “immune systems,” made stronger by the surrounding soil, become compromised.  The plants and trees may die a slow death due to nutrient starvation, oxygen deprivation, injured leaves that cannot recover, and/or their bark will become damaged and vulnerable to mold, fungi and wood-destroying insects. 
When the environment is under continual attack by the deadly effects of acid rain, the odds of survival for other resident plant, animal and insect species diminish as the ecosystem is thrown out of its natural balance.
On the flipside, NASA researchers recently discovered that one species of swampland bacteria’s ability to produce methane — a greenhouse gas that contributes to global warming — is actually inhibited by acid rain.
The EPA’s Acid Rain Program got underway in 1995 (after being enacted by Congress in 1990), which continues to seek to reduce SO2 and NOx emissions to below 1980 pollution levels.  The program originally targeted coal-burning electricity plants, and has expanded to include other types of industry that burn coal, oil and gas, too.  While the EPA touts some success in bringing down some polluters’ output by 40%, critics charge that because the program permits emission “allowance trading” among its participants, the larger industrial polluters simply pay the $2,000-per-ton fine for exceeding SO2 and NOx limits.  The EPA, however, has embraced a market-friendly approach while shooting for overall target reductions.
The primary problem with acid rain, of course, is that there is no way to contain it.  It blows with the wind and is captured and carried by localized weather systems.  Although the deterioration which acid rain causes may be slow, it is persistent.  And until we shift our reliance on fossil fuels by using various types of green energy (wind, solar, etc.), we will continue to witness the destructive consequences in all aspects of our environment, both natural and man-made, for decades to come.
Homeowners can mitigate the environmental effects of acid rain by modifying their purchasing and traveling habits, and by using building materials that are better able to withstand the corrosive effects of this modern scourge.  Inspectors can become more familiar with the problems posed by acid rain by investigating the types of building materials used, and by contacting their local EPA representative for up-to-date statistics on pollution levels for their specific area.
InspectorSeek.com
10 Oct

Mold Remediation

Author bwisnewski

Abrasive Blasting for Mold Remediation

by Nick Gromicko and Ethan Ward

Mold in the Home

Health concerns related to the growth of mold in the home have been featured heavily in the news.  Problems ranging from itchy eyes, coughing and sneezing to serious allergic reactions, asthma attacks, and even the possibility of permanent lung damage can all be caused by mold, which can be found growing in the home, given the right conditions.

All that is needed for mold to grow is moisture, oxygen, a food source, and a surface to grow on.  Mold spores are commonly found naturally in the air.  If spores land on a wet or damp spot indoors and begin growing, they will lead to problems.  Molds produce allergens, irritants and, in some cases, potentially toxic substances called mycotoxins.  Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.  Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis).  Allergic reactions to mold are common.  They can be immediate or delayed.  Molds can also trigger asthma attacks in people with asthma who are allergic to mold.  In addition, mold exposure can irritate the eyes, skin, nose, throat and lungs of both mold-allergic and non-allergic people.

As more is understood about the health issues related to mold growth in interior environments, new methods for mold assessment and remediation are being put into practice.  Mold assessment and mold remediation are techniques used in occupational health.  Mold assessment is the process of identifying the location and extent of the mold hazard in a structure.  Mold remediation is the process of cleanup and/or removal of mold from an indoor environment.  Mold remediation is usually conducted by a company with experience in construction, demolition, cleaning, airborne-particle containment-control, and the use of special equipment to protect workers and building occupants from contaminated or irritating dust and organic debris.  A new method that is gaining traction in this area is abrasive blasting.

Abrasive Blasting

The first step in combating mold growth is not to allow for an environment that is conducive to its growth in the first place.  Controlling moisture and assuring that standing water from leaks or floods is eliminated are the most important places to start.  If mold growth has already begun, the mold must be removed completely, and any affected surfaces must be cleaned or repaired.  Traditional methods for remediation have been slow and tedious, often involving copious amounts of hand-scrubbing and sanding.  Abrasive blasting is a new technique that is proving to be less tedious and time-consuming, while maintaining a high level of effectiveness.

Abrasive blasting is a process for cleaning or finishing objects by using an air-blast or centrifugal wheel that throws abrasive particles against the surface of the work pieces. Sand, dry ice and corncobs are just some of the different types of media used in blasting.  For the purposes of mold remediation, sodium bicarbonate (baking soda) and dry ice are the media commonly used.

Benefits of Abrasive Blasting

Abrasive (or “media”) blasting provides some distinct advantages over traditional techniques of mold remediation.  In addition to eliminating much of the tedious labor involved in scrubbing and sanding by hand, abrasive blasting is extremely useful for cleaning irregular and hard-to-reach surfaces.  Surfaces that have cross-bracing or bridging can be cleaned more easily, as well as areas such as the bottom of a deck, where nails may be protruding.  Areas that are difficult to access, such as attics and crawlspaces, can also be cleaned more easily with abrasive blasting than by traditional methods.  The time saved is also an advantage, and the typical timeframe for completion of a mold remediation project can often be greatly reduced by utilizing abrasive blasting.

Soda-Blasting

Soda-blasting is a type of abrasive blasting that utilizes sodium bicarbonate as the medium propelled by compressed air.  One of the earliest and most widely publicized uses of soda-blasting was on the restoration of the Statue of Liberty. In May of 1982, President Ronald Reagan appointed Lee Iacocca to head up a private-sector effort for the project.  Fundraising began for the $87 million restoration under a public-private partnership between the National Park Service and The Statue of Liberty-Ellis Island Foundation, Inc.  After extensive work that included the use of soda-blasting, the restored monument re-opened to the public on July 5, 1986, during Liberty Weekend, which celebrated the statue’s  centennial.

The baking soda used in soda-blasting is soft but angular, appearing knife-like under a microscope.  The crystals are manufactured in state-of-the-art facilities to ensure that the right size and shape are consistently produced.  Baking soda is water-soluble, with a pH near neutral. Baking-soda abrasive blasting effectively removes mold while minimizing damage to the underlying surface (i.e., wood, PVC, modern wiring, ductwork, etc.).  When using the proper equipment setup (correct nozzles, media regulators, hoses, etc.) and technique (proper air flow, pressure, angle of attack, etc.), the process allows for fast and efficient removal of mold, with a minimum of damage, waste and cleanup.  By using a soda blaster with the correct-size nozzle, the amount of baking soda used is minimized. Minimal baking soda means better visibility while working, and less cleanup afterward.

Dry-Ice Blasting

Dry ice is solidified carbon dioxide that, at -78.5° C and ambient pressure, changes directly into a gas as it absorbs heat.  Dry ice pellets are made by taking liquid carbon dioxide (CO2) from a pressurized storage tank and expanding it at ambient pressure to produce snow.  The snow is then compressed through a die to make hard pellets.  The pellets are readily available from most dry ice suppliers nationwide.  For dry-ice blasting, the standard size used is 1/8-inch, high-density dry ice pellets.

The dry-ice blasting process includes three phases, the first of which is energy transfer.  Energy transfer works when dry ice pellets are propelled out of the blasting gun at supersonic speed and impact the surface. The energy transfer helps to knock mold off the surface being cleaned, with little or no damage.

The freezing effect of the dry ice pellets hitting the mold creates the second phase, which is micro-thermal shock, caused by the dry ice’s temperature of -79º C, between the mold and the contaminated surface.  This phase isn’t as much a factor in the removal of mold as it is for removing resins, oils, waxes, food particles, and other contaminants and debris.  For these types of substances, the thermal shock causes cracking and delaminating of the contaminant, furthering the elimination process.

The final phase is gas pressure, which happens when the dry ice pellets explode on impact.  As the pellets warm, they convert to CO2 gas, generating a volume expansion of 400 to 800 times.  The rapid gas expansion underneath the mold forces it off the surface.

HEPA Vacuuming

A HEPA vacuum is a vacuum cleaner with a high-efficiency particulate air (or HEPA) filter through which the contaminated air flows.  HEPA filters, as defined by the U.S. Department of Energy’s standard adopted by most American industries, remove at least 99.97% of airborne particles that are as small as 0.3 micrometers (µm) in diameter.  HEPA vacuuming is necessary in conjunction with blasting for complete mold removal.

While abrasive blasting with either baking soda or dry ice is an effective technique, remediation will not be complete until HEPA filtering or vacuuming has been done.  Abrasive blasting removes mold from contaminated surfaces, but it also causes the mold spores to become airborne again.  The spores can cover the ground and the surfaces that have already been cleaned.  So, the mold spores need to be removed by HEPA filters.  Additionally, while some remediation companies claim that there will be no blasting media to remove after cleaning, especially with the dry-ice method, there will be at least a small amount of visible debris left by the blasting that must be removed before HEPA vacuuming can occur.  HEPA vacuuming removes all invisible contaminants from surfaces and the surrounding air.  When HEPA vacuuming is completed, samples at the previously contaminated areas should be re-tested to ensure that no mold or mold spores remain.

Abrasive blasting using dry ice or baking soda, combined with HEPA-filter vacuuming, is an effective method for mold remediation.  InterNACHI inspectors who offer ancillary mold inspection services should be aware of the benefits and applications of this technique adapted for remediating mold in homes.
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