Aluminum Siding Inspection

June 4th, 2011

Aluminum Siding Inspection

Aluminum siding is generally in decline as an exterior cladding material because vinyl siding and other materials have become more popular choices.  However, it is still among the most common forms of siding found today.  It provided many advantages over other materials when it was introduced in the 1940s.  It was installed on many affordable homes through the 1970s.

  • Aluminum Siding Inspection


    InterNACHI inspectors will encounter aluminum siding on many home exteriors and can benefit from knowing more about this common form of exterior cladding.  Homeowners may be interested in the drawbacks of this material, as well as some of the advantages it still provides in certain situations today.

    History and Manufacturing

    Aluminum siding is made from aluminum coil stock, which is chemically coated to protect the metal and then painted for further protection, as well as aesthetics.  After coating, the siding is baked for durability, with enamel often added to create desired textures.

    One of the earliest architectural uses of aluminum came in the 1920s when it was used to produce ornamental spandrel panels for the Chrysler Building and the Empire State Building in New York City.  By the 1940s, aluminum siding was being produced for use on residential structures, and quickly became popular due to the advantages it provided over other materials in use at the time.  A Pennsylvania subdivision built in 1947 was reportedly the first housing project to use solely aluminum siding.

    Its popularity remained fairly steady until the 1970s, during the energy crisis.  Aluminum siding requires a great deal of energy for production, as well as consumption of a significant amount of raw materials.  These factors largely contributed to its decline in use as other forms of exterior cladding became more popular.

    Pros and Cons

    Although aluminum siding is seeing less use these days, it possesses some attributes that may be seen as advantageous over other materials in certain situations.  There are also some areas where aluminum siding doesn’t stack up quite as well as other options.  Here are some pros and cons to consider with aluminum siding.

    Advantages

    Aluminum siding is very lightweight.
    It is fairly durable.  When properly maintained, it can last from 40 years to the life of the structure.
    It accepts the application of paint well and can be painted any desired color.
    Aluminum siding does not rust.
    It is fireproof.  In case of fire, it will not burn or melt like other claddings.
    It is waterproof.  When properly installed, it provides excellent water-resistant capabilities for exterior walls.
    Since aluminum siding contains no organic material, it will not rot or serve as a source of food for termites.
    An enamel coating baked onto the surface of the siding can mimic the look of other materials, such as wood grain, which gives the siding a more traditional look.
    Aluminum siding is recyclable.

    Disadvantages

    Aluminum siding can dent easily, and the damaged area may be difficult to repair or replace.  Many siding manufacturers offer a thin backing board of insulation that fits behind each panel.  This backing can help protect against dents.
    Although the siding takes the application of paint well, it may need to be repainted every five to 10 years.  If any oxidization has occurred, it must be removed before new paint is applied, which can make for a labor-intensive process.  In general, repainting aluminum siding requires preparation similar to repainting a car.
    Scratches in the siding will usually be immediately noticeable and unsightly because they can reveal the metal surface below the paint.
    Although aluminum will not rust because it contains no iron, as opposed to steel siding, it can corrode.  It can also be stained by the rust on adjacent materials.
    The sound of rain and hail striking it can be loud enough that some people avoid using it for this reason alone.
    Aluminum siding has gone out of style aesthetically, and is generally considered less desirable than both more traditional and newer, modern forms of exterior cladding.
    The production of aluminum siding requires a large amount of energy and raw materials.

    Inspection Tips

    Here are some things that inspectors can keep in mind while examining exterior walls clad in aluminum siding:

    Since metal siding can conduct electricity, some jurisdictions require that the siding be grounded as a safety measure.  Inspectors can check with the local authority having jurisdiction (AHJ) to find out if grounding is a requirement.
    Aluminum siding can be distinguished from vinyl siding by visual inspection.  Any dents in the siding are a clue that it is aluminum, as opposed to vinyl, which may show cracks or breaks.
    Lightly tapping on the siding can also help determine what the material is.  Aluminum has a slightly hollow and metallic sound when struck.
    Distinguishing between aluminum and steel siding can be more difficult and may require the use of a magnet, which will interact with steel but not aluminum.  Rust spots are another sign that the siding is steel.
    Properly installed aluminum siding should not be in contact with the ground.  The AHJ can be consulted for the minimum required clearance.
    If the siding has been installed in contact with the ground or below ground level, outward bulging at the bottom can be an indication that the building sills and/or lower walls have been damaged by rot or pests.

    Aluminum siding was very popular in the latter part of the 20th century and is still installed on many homes across the United States today.  InterNACHI inspectors who know more about this common type of exterior cladding will be at an advantage when inspecting exteriors and answering clients’ questions.

 

Air Sampling for Mold Inspections

June 4th, 2011

Taking air samples during a mold inspection is important for several reasons.  Mold spores are not visible to the naked eye, and the types of mold present can often be determinair sampleed through laboratory analysis of the air samples.  Having samples analyzed can also help provide evidence of the scope and severity of a mold problem, as well as aid in assessing human exposure to mold spores.  After remediation, new samples are typically taken to help ensure that all mold has been successfully removed.

  • Air Sampling for Mold Inspections


    Air samples can be used to gather data about mold spores present in the interior of a house.  These samples are taken by using a pump that forces air through a collection device which catches mold spores.  The sample is then sent off to a laboratory to be analyzed.  InterNACHI inspectors who perform mold inspections often utilize air sampling to collect data, which has become commonplace.

    Air-Sampling Devices

    There are several types of devices used to collect air samples that can be analyzed for mold.  Some common examples include:

    impaction samplers that use a calibrated air pump to impact spores onto a prepared microscope slide;
    cassette samplers, which may be of the disposable or one-time-use type, and also employ forced air to impact spores onto a collection media; and
    airborne-particle collectors that trap spores directly on a culture dish.  These may be utilized to identify the species of mold that has been found.

    When and When Not to Sample

    Samples are generally best taken if visual, non-invasive examination reveals apparent mold growth or conditions that could lead to growth, such as moisture intrusion or water damage.  Musty odors can also be a sign of mold growth.  If no sign of mold or potential for mold is apparent, one or two indoor air samples can still be taken, at the discretion of the inspector and client, in the most lived-in room of the house and at the HVAC unit.

    Outdoor air samples are also typically taken as a control for comparison to indoor samples.  Two samples — one from the windward side and one from the leeward side of the house — will help provide a more complete picture of what is in the air that may be entering the house through windows and doors at times when they are open.  It is best to take the outdoor samples as close together in time as possible to the indoor samples that they will be compared with.

    InterNACHI inspectors should avoid taking samples if a resident of the house is under a physician’s care for mold exposure, if there is litigation in progress related to mold on the premises, or if the inspector’s health or safety could be compromised in obtaining the sample.  Residential home inspectors also should not take samples in a commercial or public building.

    Where to Sample and Ideal Conditions

    In any areas of a house suspected or confirmed to have mold growth, air samples can be taken to help verify and gather more information.  Moisture intrusion, water damage, musty odors, apparent mold growth, or conditions conducive to mold growth are all common reasons to gather an air sample.  Samples should be taken near the center of the room, with the collection device positioned 3 to 6 feet off the ground.

    Ten minutes is an adequate amount of time for the air pump to run while taking samples, but this can be reduced to around five minutes if there is a concern that air movement from a lot of indoor activity could alter the results.  The sampling time can be reduced further if there is an active source of dust, such as from ongoing construction.

    Sampling should take place in livable spaces within the house under closed conditions in order to help stabilize the air and allow for reproducibility of the sampling and measurement.  While the sample is being collected, windows and exterior doors should be kept shut other than for normal entry and exit from the home.  It is best to have air exchangers (other than a furnace) or fans that exchange indoor-outdoor air switched off during sampling.

    Weather conditions can be an important factor in gathering accurate data. Severe thunderstorms or unusually high winds can affect the sampling and analysis results.  High winds or rapid changes in barometric pressure increase the difference in air pressure between the interior and exterior, which can increase the variability of airborne mold-spore concentration.  Large differences in air pressure between the interior and exterior can cause more airborne spores to be sucked inside, skewing the results of the sample.

    Difficulties and Practicality of Air Sampling

    It is helpful to think of air sampling as just one tool in the tool belt when inspecting a house for mold problems.  An air sample alone is not enough to confirm or refute the existence of a problem, and such testing needs to be accompanied by visual inspection and other methods of data collection, such as a surface sample.  Indoor airborne spore levels can vary according to several factors, and this can lead to skewed results if care is not taken to set up the sampling correctly.  Also, since only spores are collected with an air sample and may actually be damaged during collection, identification of the mold type can be more difficult than with a sample collected with tape or a cultured sample.

    Air samples are good for use as a background screen to ensure that there isn’t a large source of mold not yet found somewhere in a home.  This is because they can detect long chains of spores that are still intact.  These chains normally break apart quickly as they travel through the air, so a sample that reveals intact chains can indicate that there is mold nearby, possibly undiscovered during other tests and visual examination.
    In summary, when taken under controlled conditions and properly analyzed, air samples for mold are helpful in comparing relative particle levels between a problem and a control area.  They can also be crucial for comparing particle levels and air quality in an area before and after mold remediation.

 

AFCI Testers

June 4th, 2011

AFCI Testers

What are AFCIs?

Arc-fault circuit interrupters (AFCIs) are special types of electrical outlets or receptacles and circuit breakers designed to detect and respond to potentially dangerous electrical arcs in home branch wiring.

  • AFCI Testers

    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 (several hundred dollars) than their GFCI (Ground Fault Circuit Interrupter) indicator counterparts 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 similar role 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 outlet within the branch. InterNACHI inspectors should use AFCI indicators to inspect receptacles observed and deemed to be AFCI-protected during the inspections.

    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 8 – 12 pulses of 106 – 141 amp charges in less than a second that 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.

 

Advantages of Solar Energy

June 4th, 2011

Advantages of Solar Energy

Solar energy offers considerable advantages over conventional energy systems by nullifying flaws in those systems long considered to be unchangeable. Solar power for home energy production has its flaws, which are outlined in another article, but they’re dwarfed by the advantages listed below.

  • Advantages of Solar Energy

    Solar energy is a great choice
    The following are advantages of solar energy:

    Raw materials are renewable and unlimited. The amount of available solar energy is staggering, roughly 10,000 times that currently required by humans, and it’s constantly replaced. A mere 0.02% of incoming sunlight, if captured correctly, would be sufficient to replace every other fuel source currently used by humans.

    Granted, the Earth does need much of this solar energy to drive its weather, so let’s look only at the unused portion of sunlight that is reflected back into space, known as the albedo. Earth’s average albedo is around 30%, meaning that roughly 52 petawatts of energy is reflected by the Earth and lost into space every year. Compare this number with global energy-consumption statistics.  Annually, the energy lost to space is the combined equivalent of 400 hurricanes, 1 million Hoover Dams, Great Britain’s energy requirement for 250,000 years, worldwide oil, gas, and coal production for 387 years, 75 million cars, and 50 million 747s running perpetually for one year (not to mention 1 million fictional DeLorean time machines!).

    Solar power is low-emission. Solar panels produce no pollution, although they impose environmental costs through manufacture and construction. These environmental tolls are negligible, however, when compared with the damage inflicted by conventional energy sources: the burning of fossil fuels releases roughly 21.3 billion metric tons of carbon dioxide into the atmosphere annually.

    Solar power is suitable for remote areas that are not connected to energy grids. It may come as a surprise to city-dwellers but, according to Home Power Magazine, as of 2006, 180,000 houses in the United States were off-grid, and that figure is likely considerably higher today. California, Colorado, Maine, Oregon, Vermont and Washington have long been refuges for such energy rebels, though people live off the grid in every state. While many of these people shun the grid on principle, owing to politics and environmental concerns, few of the world’s 1.8 billion off-the-gridders have any choice in the matter. Solar energy can drastically improve the quality of life for millions of people who live in the dark, especially in places such as Sub-Saharan Africa, where as many as 90% of the rural population lacks access to electricity. People in these areas must rely on fuel-based lighting, which inflicts significant social and environmental costs, from jeopardized health through Rural, off-grid homes are excellent applications for solar powercontamination of indoor air, to limited overall productivity.

    Solar power provides green jobs. Production of solar panels for domestic use is becoming a growing source of employment in research, manufacture, sales and installation.

    Solar panels contain no moving parts and thus produce no noise. Wind turbines, by contrast, require noisy gearboxes and blades.

    In the long run, solar power is economical. Solar panels and installation are high initial expenses, but this cost is soon offset by savings on energy bills.  Eventually, they may even produce a profit on their use.

    Solar power takes advantage of net metering, which is the practice of crediting homeowners for electricity they produce and return to the power grid. As part of the Energy Policy Act of 2005, public electric utilities are required to make available, upon request, net metering to their Manhattan, and much of the northeast USA, goes dark in August, 2003customers. This practice offers an advantage for homeowners who use solar panels (or wind turbines or fuel cells) that may, at times, produce more energy than their home requires. If net metering is not an option, excess energy may be stored in batteries.

    Solar power can mean government tax credits. U.S. federal subsidies credit up to 30% of system costs, and each state offers its own incentives. California, blessed with abundant sunshine, and plagued by high electric rates and an over-taxed grid, was the first state to offer generous renewable-energy incentives for homes and businesses.

    Solar power is reliable. Many homeowners favor solar energy because it is virtually immune to potential failings of utility companies, mainly in the form of political or economic turmoil, terrorism, natural disasters, or brownouts due to overuse. The Northeast Blackout of 2003 unplugged 55 million people across two countries, while rolling blackouts are a part of regular life in some South Asian countries, and occasionally in states such as California and Texas.

    Solar power conserves foreign expenditure. In many countries, a large percentage of earnings is used to pay for imported oil for power generation. The United States alone spends $13 million per hour on oil, much of which comes from Persian Gulf nations. As oil supplies dwindle and prices rise in this politically unstable region, these problems continue to catalyze the expansion of solar power and other alternative-energy systems.

    In summary, solar energy offers advantages to conventional fossil fuels and other renewable energy systems.

 

Adjustable Steel Columns

June 4th, 2011

Adjustable Steel Columns

Adjustable steel columns, also known as screw jacks and beam jacks, are hollow steel posts designed to provide structural support. An attached Adjustable steel columnthreaded adjustment mechanism is used to adjust the height of the post.

  • Adjustable Steel Columns

    A few facts about adjustable steel columns:

    They are usually found in basements.
    In some parts of North America, adjustable steel columns are called “lally columns,” although this term sometimes applies to columns that are concrete-filled and non-adjustable.
    They can be manufactured as multipart assembles, sometimes called telescopic steel columns, or as single-piece columns.

    The following are potentially defective conditions:

    The post is less than 3 inches in diameter. According to the 2006 International Residential Code (IRC), Section R407.3, columns (including adjustable steel columns)…

    “shall not be less than 3-inch diameter standard pipe.”

    Poles smaller than three inches violate the IRC, although they are not necessarily defective. A 2½-inch post may be adequate to support the load above it, while a 4-inch post can buckle if the load exceeds the structural capacity of the post. Structural engineers, not inspectors, decide whether adjustable steel posts are of adequate size.

    The post is not protected by rust-inhibitive paint. The IRC, in section R407.2, states,

    All surfaces (inside and outside) of steel columns shall be given a shop coat of rust-inhibitive paint, except for corrosion-resistant steel and steel treated with coatings to provide corrosion resistance.

    Inspectors will not be able to identify paint as rust-inhibitive. In dry climates where rust is not as much of a problem, rust-inhibitive paint may not be necessary. Visible signs of rust constitute a potential defect.

    The post is not straight. According to some sources, the maximum lateral displacement between the top and bottom of the post should not exceed 1 inch. However, tolerable lateral displacement is affected by many factors, such as the height and diameter of the post. The post should also not bend at its mid-point. Bending is an indication that the column cannot bear the weight of the house.
    The column is not mechanically connected to the floor. Inspectors may not be able to confirm whether a connection between the post and the floor exists if this connection has been covered by concrete.
    The column is not connected to the beam. The post should be mechanically connected to the beam above to provide additional resistance against lateral displacement.
    More than 3 inches of the screw thread is exposed.
    There are cracks in upstairs walls. This condition may indicate a failure of the columns.

 

Acid Rain and Inspectors: Buildings at Risk

June 4th, 2011

“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.

Abrasive Blasting for Mold Remediation

June 4th, 2011

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-BlastingSoda-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.

REI-Specialist (Blog)

October 4th, 2010

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Rodney Sims
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