Defensible space refers to the area surrounding a building that is mitigated to protect it from wildfires. Along with the quality of a building’s roofing material, adequate defensible space is one of the most important factors in determining a building’s ability to survive a wildfire. Inspectors should know enough about defensible space to educate their clients, particularly in fire-prone regions.

Defensible space performs the following functions:

1. Ideally, a carefully maintained defensible space will not contain enough fuel to allow a wildfire to reach a house. Even if the space is breached, the fire will have been slowed and weakened, helping firefighters to defend the house.
2. A defensible space provides an accessible area for fire trucks to park and firefighters to work during a structure fire.
3. If there is a pond near a burning house, it can be used to replenish a fire truck’s water supply. The perimeter of the pond should be thinned of trees and brush sufficiently so that firefighters can access it.

Zone 1:  The first 15 feet from a home should be devoid of all flammable vegetation. Firewood and other flammable materials should not be stored in this region.

Zone 2:  This area of fuel reduction should extend from Zone 1 outward to between 75 to 125 feet from the structure. Trees and large shrubs should be no less than 10 feet apart, especially in steep terrain. Trees must also be pruned to a height of 10 feet from the ground, and any “ladder fuels” (vegetation with vertical continuity) removed from the base of the trees. Grass, trees and shrubs in this region should be green and adequately spaced. Pine needles, dead leaves, branches, dead or dying vegetation and other flammable debris on the ground should be removed whenever they appear.

Zone 3:  This region of traditional forest management is of no particular size, although it normally extends to the property limits. More trees are permitted here than in Zone 2, although their health and vigor should be maintained.

Backflow is a potential problem in a water system because it can spread contaminated water back through a distribution system. For example, backflow at uncontrolled cross connections (cross-connections are any actual or potential connection between the public water supply and a source of contamination or pollution) can allow pollutants or contaminants to enter the potable water system. Sickness can result from ingesting water that has been contaminated due to backflow.

Atmospheric Vacuum Breakers 

Backflow prevention for residences is most commonly accomplished through the use of atmospheric vacuum breakers (AVBs). AVBs operate by allowing the entry of air into a pipe so that a siphon cannot form. AVBs are bent at 90 degrees and are usually composed of brass. Compared with backflow preventer assembles, AVBs are small, simple and inexpensive devices that require little maintenance or testing. They have long life spans and are suitable for residential purposes such as sprinkler systems. InterNACHI inspectors can check for the following:

Some types of assemblies are common in commercial and agricultural applications but are rare for residential uses. The appropriate type of backflow preventer for any given application will depend on the degree of potential hazard. The primary types of backflow preventers appropriate for use at municipalities and utilities are:

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.

Above:  an overloaded outlet with no cover

It’s a Visual Inspection

A “visual” inspection means that a home inspection report is limited to describing conditions in those parts of a home that an inspector can see during the inspection. Obviously, parts of the home that are permanently hidden by wall, ceiling and floor coverings are excluded, but so are parts of the home that were inaccessible during the inspection for some other reason. Some reasons might include lack of an access point, such as a door or hatch, or a locked access point, or because an occupant’s belongings blocked access, or because of dangerous or unsanitary conditions.

There can be many more reasons. The point is that if an inspector can’t see a portion of the home, the inspector can’t assume responsibility for ensuring that a safe and proper condition exists or that systems are operating properly in that hidden space.

Safety

Safety can be a matter of perception. Some conditions, such as exposed electrical wiring, are obviously unsafe. Other conditions, such as the presence of mold, aren’t as clear-cut.

In the example of the possible existence of mold, it’s difficult to accurately call it out during a general home inspection because mold sometimes grows in places where it can’t be readily seen, such as inside walls, making its discovery beyond the scope of the inspection.  Also, the dangers to human health are from the inhalation of spores from indoor air.

Above:  the cutting torch and gutter system of roof drainage management

Inspectors will also examine the major accessible components of certain systems as required by the Standards of Practice. Furnace air filters are one example.

A home inspection is not technically exhaustive, meaning that systems or components will not be disassembled as part of the inspection. For example, an inspector will not partially disassemble a furnace to more accurately check the condition of the heat exchanger. Inspectors typically disclaim heat exchangers.

Hazardous Materials

Asbestos, mold, lead, water purity, and other environmental issues or potential hazards typically require a specialist inspection, and may additionally require laboratory analysis.

Home Inspectors are Generalists

Above:  the result of subfloor movement

Inspector Qualifications

Very few home inspectors have been in the inspection industry for their entire working lives. According to an InterNACHI poll, about half the home inspectors have a background in the building trades. Those with a construction background started with a general idea of the systems and components that they might find installed, as well as how those systems age and fail.

This doesn’t mean that inspectors with a background in something other than the building trades are not qualified — only that they started in the inspection industry at a relative disadvantage. Building the skills and developing the judgment to consistently recognize and interpret evidence correctly and make appropriate recommendations are things that can be improved with practice and continuing education.

Managing Expectations

Part of a home inspector’s job is to manage the expectations of their client. This is especially true when a client has never dealt with a home inspector before. Explaining the limitations of a home inspection to a client will help them develop realistic expectations concerning what to expect from a home inspection report, and what lies beyond the scope of the inspection.

When a home buyer is interviewing inspectors, the buyer should ask about how the inspector handles special safety concerns.

Disclaimers are portions of an inspection agreement or report in which an inspector notifies the client that the inspector will not accept the responsibility for confirming the condition of a portion of the home or of a particular system or component.

History

Asbestos cement first came into use as an exterior cladding after 1907, when Austrian engineer Ludwid Hatschek came up with a way to shape the material into sheets, allowing it to be manufactured as siding and shingles. By the 1920s, the National Board of Fire Underwriters recommended that asbestos cement replace wood as siding and roofing material because of its superior fire-resistant properties. This recommendation from a nationally known insurance board contributed to a boost in sales and, by the 1940s, hundreds of thousands of homes in the U.S. had been constructed using asbestos cement siding.

During the late 1960s and early ‘70s, however, the news media began to report on the health hazards associated with asbestos. As reports increased, concern grew, so the federal government took action and, in 1973, the EPA banned the use of asbestos in the manufacture of building products.

Health Risks Associated with Asbestos Cement

Asbestos fibers are a proven health hazard if inhaled. Asbestos dust is a known cause of a type of lung cancer called asbestosis. Mesothelioma, another deadly form of cancer that attacks internal organs, can also be caused by exposure to asbestos. However, asbestos cement siding that has been properly installed and is not in a state of decay presents no health risks as long as it remains undisturbed. This is because the cement binds the asbestos fibers and prevents their release into the air, under normal use and maintenance.

The EPA deems asbestos to be hazardous when it is in a friable state, meaning that it can be crumbled, crushed or pulverized by hand pressure. Crushed asbestos in a powdery form can allow its particles to become airborne and inhaled, causing potential health problems. Asbestos cement products that are not in a friable state are not considered hazardous. The only potential danger is when the cement is disturbed in a way that causes the asbestos fibers to become airborne.

If mechanical activities performed on the siding, such as chipping, sawing, grinding or sanding, allow particles to become airborne, then the cement is considered in a friable state and, consequently, hazardous. Deterioration can also lead to particles becoming airborne and potentially dangerous.

Advantages

• Asbestos cement siding is highly fire-resistant and will not burn or melt the way vinyl and wood siding will.
• It resists termite damage.
• It resists rotting.
• It has been manufactured with textures intended to simulate the look of other cladding materials, such as wood grain.
• It is fairly easy to clean and maintain.
• Unlike more porous siding materials, such as wood clapboard, asbestos cement siding will not quickly soak up paint, which allows it to be painted more easily.

Disadvantages

• Asbestos cement siding is very brittle and can be easily chipped, cracked or broken.
• The use of a pressure washer for maintenance can crack the siding and lead to moisture intrusion, if the pressure setting is high enough.
• Asbestos cement can be dangerous if pulverized by sawing, sanding, breaking, etc.
• It is difficult to find replacement siding for repairs.
• This product cannot be refurbished, unlike other forms of siding.  Wood clapboard, for example, can be sanded and re-painted, and cedar shake siding can be sand-blasted and re-stained.  Either of these methods can restore wood close to its original state.  But this is not possible with asbestos cement siding.
• It is no longer considered aesthetically desirable.

Maintenance

Damage and deterioration can lead to structural and health issues, so proper maintenance of asbestos cement building materials is a primary concern.  Keeping the siding clean and performing any minor repairs as soon as they become necessary are both important.

Asbestos cement siding is fairly brittle and has little resistance to cracking, chipping and damage from impact, which can cause asbestos particles to become airborne.  Damage to the siding can also lead to other damage related to moisture intrusion.  Damaged areas that cannot be fixed can be replaced with non-asbestos fiber cement by a professional.  Specific fiber cement materials have been manufactured for repairs that are intended to mimic the look of asbestos cement siding.

Landscaping features, such as a row of shrubs, can be incorporated around the home to help protect the siding from impact damage.

Inspection Tips

Here are some common problems associated with asbestos cement siding that inspectors are likely to encounter:

• Chipping and cracking often occur with this brittle material.
• Fasteners used to hold the siding in place may deteriorate at a faster rate than the siding.
• Discoloration and staining may occur from corrosion or runoff from an adjacent material.  The discoloration may be normal, but it could also indicate a chemical reaction that has decreased the durability of the material.
• Like many other cement products, efflorescence may appear on asbestos cement siding.  This crystalline growth can indicate that water is passing through the material, promoting deterioration of the cement.
• Biological growth, such as moss and algae, can occur if conditions are favorable.  This growth may stimulate surface deterioration and staining.