Stephen Ternullo & Associates, Inc.
SteveT@STAengineering.us P: (586) 868-0220 www.STAengineering.us

THE

FORENSIC

ENGINEERING

REPORT



THE LIFE AND DEATH OF A BUILDING

It’s a familiar scenario in science fiction novels and movies: A catastrophic event of some kind occurs, and Earth’s human population is wiped out, leaving the rest of the world intact. What would happen then? Nature would get on just fine without us. Though our family pets might find it challenging to fend for themselves, wild animals would proliferate, and vegetation and forest cover would thrive and spread.

But what about the built environment? Just like the common automobile, ski slope, or nuclear reactor, buildings and infrastructure need our constant care and maintenance. Without it, the natural elements would ravage our structures, which would effectively die and be swallowed by nature completely.

Within just two to five years of neglect, most buildings would show evidence of water damage. With no one to maintain building grounds, unchecked plant and tree growth against a structure would lead to an increase in moisture levels. High moisture content means harmful growth of molds, mildew, algae and even creeping plants that can cause cracking in the building’s exterior, leading to water penetration.

Untamed vegetation wouldn’t be the only threat. Exposure to weather over time would also lead to decay. Without regular maintenance, rain, wind, sun exposure and frost could cause corrosion and cracking on the exterior of a building, leading to even more opportunities for water damage.

Within just 15 to 20 years, dramatic building envelope damage would be evident. Once a building’s envelope is compromised, the natural elements are able to work their way inside a building, causing interior walls and ceilings to swell and crack or sag, leading to eventual collapse of the structure.

Though most buildings aren’t so completely neglected as suggested in our science fiction scenario, it helps to illustrate how a little proactive building maintenance can prevent costly structural failures down the road. SMT’s Investigative Monitoring solution makes it possible and economical to monitor the health and performance of commercial and residential structures, and provide early warning detection on structural failures.

Using a variety of on-site sensors that measure factors such as moisture, differential pressure, temperature and humidity, SMT’s technology monitors a building system over time, and analyzes data online. When a problem is detected, wired or wireless electronics provide feedback in real time, with status reports sent directly to your email inbox.

Construction liability for moisture and mold is on the rise, and insurers are responding by eliminating water damage coverage from their policies. With SMT’s early warning moisture detection system, building owners and other stakeholders are made aware of their building’s moisture characteristics and accumulation locations, and can take action before moisture causes severe damage. Changes in weather and other environmental factors are automatically correlated to moisture-related events within the structure that is being monitored.

The parameters of temperature, relative humidity and direct material moisture content are of primary concern for long-term monitoring, investigation and risk mitigation. The temperature and relative humidity sensors enable the monitoring of the wall or roof cavity air space conditions including dew points, vapor pressure and condensation potential. The direct moisture content gives the amount of moisture in the external wall sheathing which can come from exterior leaks in the cladding or from condensation or moisture sources from the interior occupants.

SMT's Building Analytics on-line monitoring center provides data collection, processing, analysis, graphical display and long term storage of sensor data. Analytics tracks the state of each job and sensor to alert users promptly when issues arise. Automated reports, drawing sensor overlay status and dashboard information presentation make the Building Analytics web based software a key to understand the information coming from the sensors.

Communication from the sensors and data acquisition system internal to the Building Analytics On-line Monitoring Centre can be achieved mainly by two methods: wireless live or wireless data logging communication.

Wireless Live Communication

Wireless live communication is an excellent solution for short or long term monitoring in any type of structure with-in the approximate 300 foot wireless coverage to the Building Intelligence Gateway (BiG), pending wall types and wireless interference which are installation site specific. An extension receiver or repeater can be installed with-in the building to expand the area of coverage from the wireless system. Most common areas of wireless extension coverage are located on roof tops or through vertical risers to reach sensors and A2 data acquisition nodes on different floors.

The A2 node endpoints do not need reprogramming or configuration when entering a Wireless Point to Point (live) network from a Data logging remote data collection methodology – this feature is excellent for transition from construction monitoring to permanent long term monitoring projects at a low cost.

Wireless Data Logging Communication

Wireless Data Logging systems enable the sensors and data acquisition hardware to be installed in sparse configurations, and installed in specific areas of interest, eliminating the immediate need to install communication wires or wireless receivers permanently or semi-permanently in the building. The wireless data logging equipment can be embedded in the wall, roof or alternative areas located with-in which are hard to access or require permission to retrieve. The sensors and acquisition system can be installed on high elevations on the side of the building or located within private suites.

Simply bringing a notebook PC with a receiver into the proximity of 300 feet (pending on construction type) from the sensor location retrieves the data through wireless means. The physical access to the data logger is no longer required to retrieve data as in the case of USB data loggers. The expense of a permanently installed remote gateway and site Internet connection is eliminated.

Our real-time sensor analysis and remote data collection enable engineers and researchers to validate their designs, materials and methods, while reinforcing quality assurance throughout varied forms of construction & renovation. This creates more efficient buildings, with a lower environmental impact and monetary cost.

Building intelligence monitoring kits can be installed during or after construction, and can be tailored for each project. The monitoring systems are a costeffective way to have detailed information about a structure made available at your fingertips. This information can help you extend the life of your building.

This technology can have great value to Investigative Engineers, Insurance Carriers and Self Insured Companies in properly accessing their claims and mitigating additional building damages in the future.

By: Jason Teetaert, P.E., Structural Monitoring Technology

WATER, WATER EVERYWHERE?

As the rainfall continues to mount at various locations around the country, it is not just water levels that are rising, but the number of claims centered on its effects. Approximately 40% of all claims involve water damage. High winds coupled with the saturated soil can substantially increase damage to underground structures, especially foundations and basements.

The typical approach to investigations such as these is to have an engineer go to the site, and note the condition of the concrete slab, the wall/concrete slab interface, to investigate the cause of the water and/or moisture intrusion. While there are many conventional approaches to investigating the reasons for storm-related damage and/or excessive water infiltration into buildings and homes, new technologies exist to allow a more detailed investigation of the building environment to be ascertained based on moisture and humidity monitoring. This allows for the investigative engineer to accurately ascertain the origin and cause. These new technologies are also preventative measures which can save insurers and insureds billions of dollars.

The use of fiber optic moisture sensors have been shown to accurately measure the level of moisture and relative humidity RH within a building envelope. Based on a shift in wave length of the light based on the make-up of the gel/polymer used on the sensing device, this wavelength shift can be used to correlate with moisture level. The optical fiber-based sensors have found wide spread use, due to their unique advantages; including low weight, small footprint, insensitivity to electro-magnetic interference, and most especially, their remote sensing capability. Coupled with fiber optic temperature measurement, the relative humidity within a building space can be measured and monitored to nail down where the problems are occurring. The accurate monitoring of the building with the use of fiber optic networks, allows the building to be accurately monitored over the course of a week or a month.

Increasingly, permanent fiber optic installations are installed as part of the new “smart” buildings as building intelligence systems. Fiber optic humidity sensors continue to attract a lot of research interest.

If you are suddenly dealing with a number of substantial claims related to the record rainfalls and need an accurate assessment, over and above the normal investigation, give us a call.

And, if you are a risk manager or self-insured company looking at ways to minimize potential damage, the building intelligence features described in this newsletter are products/services you can speak about with your local I-ENG-A member.

The bottom line is if we can work together to prevent water damage, we could save billions.

By: Steve Feeney, P.E.


THE PURPOSE OF THE GREEN WIRE IN POWER CIRCUITS FOR THE NON-ENGINEER

The drummer in my band hands me one of our outlet strips and says, "Be careful, it won’t work right, the ground plug is snipped off." He was sober.

What is the purpose of the ground stab on a plug and the green wire, why do so many misunderstand? His statement has some truth and some error. Was he in error because he is a drummer or because generally most people really don’t understand the ground plug?

The answer is because he is a drummer, and, he is member of the group "most people." His statement "Be careful" is entirely true with the ground plug. Many understand the ground is for safety, many even realize the ground plug stab is connected to the "green" wire. The next part, "It won’t work right" is somewhat true, but, for another reason. Without the ground plug, when I touch a shorted, but otherwise functional, sound board and my teeth chatter, true, something isn’t working right but it is me not working right; my equipment is working fine.

Let’s define a technical term: equipotential--means equal potential. Two or more items are at the same voltage potential. There would be no reading on a voltmeter between items of equipotential. When all electrical items are interconnected with a green wire, everything stays at equipotential. Since the green wire is also interconnected with building steel, concrete, and the earth; a barefoot person standing on concrete is at the same potential, and may safely touch the frame of a freezer, for example.

Current is the parameter that kills, not voltage. It takes voltage, overcoming resistance, to create current. It is also the current that creates the useful purpose for electricity. Humans cannot take much current and live, 10 milliamps (.01 amps) begins to hurt, and most people begin to have cardiac problems at that level.

The National Electrical Code (NEC) requires the green (or bare) wire shall not carry any current and be attached to non-current carrying parts of the equipment. If it does carry current, the NEC requires it to be sized and properly connected to cause the feeding breaker, or fuse, to trip.

When would it carry current? It occurs during a short circuit, this is when the black wire, the voltage source wire, accidentally touches those non-current carrying parts of the equipment. The black wire in a circuit attaches to the breaker or fuse. The wire is normally insulated from the parts of the equipment people touch. When this wire touches the metal parts of equipment, such as a sound board, it raises the equipment voltage to wall receptacle voltage of 120volts. The green wire, attached to the metal sound board and to the low side of the building power transformer, will now short to the 120 volts supply and create enough high current to trip the feeding breaker. The power, of course, is now off but the risk of electrocution is also safely gone.

The question is what about older homes not having that third ground socket in the receptacle? The green wire doesn’t exist and if the black wire happens to accidentally touch the metal chassis, the equipment will be at wall voltage and the breaker will not trip. If the equipment is built to UL standards, neither the black or white wires will touch the metal chassis. Since older plugs can be turned either way when plugged in, the shorted equipment chassis would be hot sometimes and not hot at other times. What is provided by the electrical industry to be the equivalent, in safety, to the green wire? It is the Ground Fault Interrupter (GFI) receptacle. You will find them typically in kitchens, bathrooms, and outdoor receptacles. It trips out the receptacle when the current on one of the plug stabs does not equal the current in the other. The industry assumes the difference in current is going through a human.

Always verify the green wire is well connected to its intended location. Provide GFI’s as alternates for additional safety in older homes.

My drummer, soberly read this explanation and I thought he understood it, but he handed me a green extension cord looking strangely confused.

By: Mike Surratt, P.E.