Snow Covered Roofs CollapseIt’s been quite a winter for Northern Alberta with an accumulation of more than 60 cm of snow in the Edmonton area alone since the New Year. The volume of snow has wreaked havoc with property owners as some roofs col-lapsed under this weight. However, it should not be assumed that the snow is excessive or that the building is not ‘up to code’ just because the roof collapses. There are other contribut-ing factors that need to be considered in order to determine liability. A structural assessment can determine whether or not snow loads are excessive, identify structural distress, and can recommend a removal process that will ensure no further structural damage occurs.

Snow loads are influenced by weather and moisture conditions, roof configuration, wind direction, slope direction and geographic loca-tion. For the Edmonton area (the Calgary area is similar), the Alberta Building Code states that the design snow load for a home or small building is106kg/m2 or 22 lb/ft2. By the end of January 2011, Edmonton's annual snow ac-cumulation was approaching the design snow load in place for the average building, making roofs more susceptible to collapse.

While the Alberta Building Code provides a minimum design requirement, a prop-erly constructed building should be able to withstand significant snowfall, often in excess of the code design. It is often other factors in combination with age, dramatic weather changes and heavy snow loads that can bring a roof to the point of collapse.

Here are some common factors that contribute to roof collapse:

Construction deficiencies

Improper modifications and inadequate maintenance can contribute to roof collapse under significant snow loads. Modifications can include: insulation without adequate roof deck ventilation, re-roofing over three or more layers of shingles, and/or modifica-tions to the structure causing weakening of the roof ’s load tolerances. A roof in an older building may also be “under-built” and more vulnerable to structural problems. These de-ficiencies, combined with excessive loading, can lead to roof collapse.

Weight and distribution of loading

The weight of the snow can be unevenly distributed with concentrated accumula-tion of snow in a particular area. This can create increased snow loading on parts of the roof. Roof pitch (3/12 pitch or less) can affect accumulation as snow is less likely to slide off flatter roofs. Also, drifting snow can accumulate against protrusions from the roof or uneven roof lines, such as rooftop equipment or walls between roof levels, in turn increasing the loading on the roof in a particular area. In addition, rain falling on accumulated snow will add more weight.

Excessive loads, uneven weight, and drifting snowfall can contribute to increased snow loads and possible roof collapse.

Ice damming

Significant snow accumulation, combined with warming weather, can result in ice damming. An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow (water) from draining off the roof. Insufficient attic insulation and/or attic ventilation can cause roof snow to melt and slide down to the eaves, where the roof surface is cooler and the melting snow freezes to the roof. Subsequent melt-ing causes water to pool behind this dam and can lead to water seeping between the shingle layers, wetting the roof deck and ingressing into the ceilings and walls. This creates favourable conditions for deteriora-tion of a roof ’s structural members, de-creasing roof fastener strength, and possible roof collapse.

Every structure is unique and the cause of a collapse can result from multiple contrib-uting factors. The weight of the snow on a roof may not be the only factor. Design, material, weather conditions, and modifica-tions all need to be examined and con-sidered. A structural engineer is uniquely positioned to assess each individual case, determine which factors contributed to the collapse, and provide technical insight to assist in the assessment of liability.

02 Fire Investigation – The First 72 Hrs.

Protecting Your Interests

03 Crash Testing Tools

Instrumentation

Spring Seminar - May 11 & 12

Sintra Launches Blog

04 Resolving Slip & Fall Liability Claims

Slip Resistance Tester

Spring 2011

www.resolvematters.ca

Fire Investigation – The First 72 HoursProtecting Your Interests

A fire starts in a section of a multi-tenant warehouse and eventually destroys the entire structure and contents. The owner of the building is not one of the tenants and all of the tenants sustained fire and smoke damage. The fire is determined by the local fire department to have started in one of the tenant’s spaces and the cause attributed as electrical.

When it comes to resolving liability in fire claims, identifying the origin and cause is a key step. Given the information gath-ered in the example above, there are many interested parties that will be looking to one another to try to recover damages from the loss. The adjuster for the tenant where the fire started might assume that their insured’s liability policy would be respon-sible for the entire loss, but rarely are losses that simple.

Back to the case above, electrically initiated fires are over-reported and this is a very generic description. What if renovations had been recently performed? What if parts of the building were improperly separated, from a fire perspective, allowing the fire to spread from one space into another? What really failed? Why? Was it a building system or a tenant’s device? What if it was found that a fire suppression system failed to activate? All of these questions could lead to information that might shift liability, but they need to be identified during the initial investigation if they are to result in success-ful subrogation.

The first 72 hours following a fire loss are critical to the engineering investigation. This is when a fire investigator is best po-

sitioned to identify the origin and cause. It is also the time when contributory compo-nents should be assessed and identified in order to preserve evidence for subrogation opportunities later on.

Subrogation opportunities don’t always ex-ist, nor should they be frivolously pursued. However, it is important to look past the initial causation layer to determine if any third party might be responsible for the loss or any portion of it.

Contributory ComponentsOne of the challenging aspects of fire inves-tigation is the multi-disciplinary nature of the investigator's job. Fires can be caused by, or involve, multiple contributing compo-nents. Consequently, private fire investiga-tors need to understand not only the science of fire behaviour, but also have a working understanding of building construction, electrical/mechanical systems and product design.

In a fire loss, your fire investigator must be able to evaluate the components or systems related to the cause of the loss.

Evidence PreservationPhysical evidence critical to pursuing a suc-cessful subrogation claim can be destroyed during the restoration process if it is not identified during the initial investigation as being significant to the loss. Identifying the right physical evidence to preserve in fire losses can be difficult. The fire investigator needs to identify any significant physical evidence related to the cause and spread of the fire to ensure that the evidence is preserved. During the preservation process,

photographs need to be taken to ensure that the context is captured, including where the physical evidence was located and how it was found. If done properly, any issues related to spoliation of the evidence will be avoided.

Notifying Potentially Liable Third PartiesOnce the physical evidence has been identi-fied and properly preserved, it is impor-tant that potentially liable third parties be notified. While it is not the role of the fire investigator to do this, it is a critical step in protecting your interests. As potentially liable third parties are identified (manufac-turer or installers of suspect components), notice should be communicated with limited (if any) evidence alteration. When alteration of evidence (i.e. destructive and/or non-destructive testing) is required as part of the ongoing investigation, each party should be notified and invited to attend if they choose.

Many sound subrogation opportunities are compromised due to spoliation of evidence either because it was not identified as being contributory during the initial investigation, or because the evidence was altered during the investigation or in subsequent analysis. While subrogation is often pursued after the payment of a claim has been made, it is often too late to identify potentially liable third parties once the scene has been restored and the evidence is gone.

Identifying and protecting subrogation op-portunities is vital in the first 72 hours after a fire loss is critical. Involving a forensic engineering investigator at the outset of a fire claim investigation can help ensure that your interests are protected.

Crash Testing Tools – InstrumentationThe 5th wheel is literally a smaller, non weight bearing 5th wheel that gets temporar-ily mounted to one door of the test vehicle. This 5th wheel is fitted with an opti-electric rotary transducer that produces 2024 pulses per rotation. This pulse per rotation number, coupled with the diameter of the wheel, gives us a positional resolution of less than 3mm per pulse. The data acquisition hub has a built-in clock that can measure the time between pulses to accuracies of better than 0.001 seconds. These two data streams are combined to give us an accurate report of the velocity of the test vehicle, both before and after the impact, which is recorded in a spread-sheet data file.

The acceleration com-ponent of the vehicle dynamics is measured by a pair of piezo-electric accelerometers that are temporarily mounted to the floor pan of the test vehicle. One accelerometer is aligned with the longitudinal axis of the vehicle and the other the transverse axis. These transduc-ers return a voltage signal proportional to the magnitude and direction of the accelera-tion they experience, which is converted to an acceleration value using the calibration

One of the ongoing research projects that Sintra Engineering is engaged in is a study of the parameters and results of low speed automobile accidents (less than 15 kilometers per hour). The current test series we are en-gaged in consists of a variety of single vehicles impacting a solid barrier on both the front and rear bumpers, at a range of speeds up to a maximum of 15 kilometers per hour.

The test vehicles are carefully measured and photographed in their pretest condition; with particular attention being paid to the condi-tion of the front and rear bumpers, covers and structural members. We also examine the fit and alignment of the front and rear quarter panels. After each impact the vehicle is photographed again, and all of the measure-ments are repeated to quantify any damage or displacement, no matter how subtle.

In addition to the physical examination and measurements, we also record data such as velocity and acceleration, using a data acqui-sition system. The system consists of a linear position transducer called the 5th wheel, a set of perpendicularly mounted accelerometers, a floor mounted ribbon switch, and a data ac-quisition hub that connects all the individual instruments to a single computer.

number that comes with each accelerom-eter. These acceleration values are recorded as separate data streams in their own data files, just like the velocity data. To ensure the velocity and acceleration data streams are accurately synchronized the signal from the ribbon switch is recorded in all of the individual data files. That’s the technical side of things.

The real value of the results garnered from this type of testing is in the correlations that can be drawn between the measured resul-tant damage of the impact and the recorded

dynamics of a given impact. It means that our engineers are able to more accurately es-timate the changes in velocity experienced by a vehicle occupant

by measuring a vehicle’s damage following an impact. This can help answer questions about the likelihood of injury expected by an occupant involved in a low speed collision. This can be valuable information in under-standing your position in a claim involving an occupant reporting serious or sustaining injuries following a low speed impact.

Join us for an informative half-day seminar where we will be delving into the different technological advances that have changed the way motor vehicle collision claims can be investigated.

We will be focusing on the various vehicle control modules that record information and what kind of information can be obtained from them. Also, we will be taking a close look at after-market global positioning sys-tems that track vehicle motion and position. Furthermore, the advent of social networking sites has changed the technological landscape and opened the door to a stream of informa-tion that can be used to track people, their whereabouts and activities. This information can be used to corroborate the activities of a party before, during, and after a collision.

Sintra Engineering has launched a company blog on our website www.resolvematters.ca. The blog is intended to provide insight, expertise, and report on newsworthy stories and issues that matter most to our clients. It’s a chance for us to connect, interact and communicate with our clients. Cli-ents are able to share and/or comment on all of our blog posts and subscribe to our blog feed.

Watch out for a consistent stream of posts and feel free to comment on and share information that is important to you. We appreciate the opportunity to provide you with technical insight and look forward to your feedback.

NEW BLog SPRINg SEMINaR May 11 &12

The legal implications of obtaining and using this information as part of the claims resolu-tion process will be discussed.

• ThisfourhourAlbertaInsuranceCoun-cilaccreditedseminarisidealforadjust-ers,lawyers,andriskmanagersdealingwithAutoandBodilyInjuryClaims.

• SpeakerswillincludeengineersfromSintraEngineeringandlawyersfromFieldLaw.

• May11th|CalgaryMay12th|Edmonton

• Costis$85.00.Fullbreakfastandre-freshmentsincluded.

To register for the seminar, visit our website at www.resolvematters.ca and download our brochure.

This can help answer questions

about the likelihood of injury

expected by an occupant

involved in a low speed collision.

Return Undeliverable

Canadian addresses to:

Sintra Engineering Inc.

10620 - 105 avenue

Edmonton, aB T5H 0L2

PM41444017

Resolving Slip and Fall Liability ClaimsSlip Resistance TesterSlips, trips, and falls result in some of the most common and costly liability claims against business owners. (Source: Insurance Bureau of Canada). If you are handling a claim involving a slip and fall, we have a tool that can provide insight into the factors that contributed to the incident and can assist you in resolving liability.

What is the key element in most slip and fall situations?

The key element in most slip and fall situations is the slip resis-tance between the ground surface and the claimant’s footwear. It is an unexpected decrease or increase in traction that causes instability in an individual’s gait which can then lead to the oc-currence of a slip.

What are the main factors that influence traction or slip resistance?

The main factors that influence traction, or slip resistance, are the ground surface, environmental conditions, and footwear. Char-acteristics related to all three of these factors must be considered when assessing a surface's slip resistance. Some characteristics in-clude the ground slope, ground geometry, surface texture, surface finish, ambient temperature, precipitation (when outdoors), sur-face contamination (e.g. water, grease, etching agent), footwear material, and/or contamination of the footwear sole.

How can slip resistance of a surface be measured?There are various standards that outline methodologies to measure the slip resistance of a floor material or ground surface. Typically, these test methods require a weighted block to be pulled across the test surface to assess a friction or slip resistance. Even though tests can be conducted in this manner to assess the slip resistance of a particular surface, the resulting measure-

ments typically do not provide an accurate indication of the increased or decreased traction experienced by an individual in a particular incident. In order to gain better insight for a specific case, Sintra Engineering utilizes a slip resistance tester.

What is a slip resistance tester?

A slip resistance tester is designed for testing walkway trac-tion. The tester is portable, which allows for easy travel and site use. We can test the actual incident surface with different shoe materials and under different environmental conditions (e.g. wet, dry, chemical application). The tester functions by contacting the test surface with a footwear sample in a man-ner similar to how an individual steps down onto the ground. This procedure produces slip resistance values that more ac-curately represent what an individual experiences as he or she steps on the surface.

What are the benefits of a slip tester?

The benefit of using the slip resistance tester is that compari-sons of slip resistance can be made on site. Also, the influ-ence of ground contaminants on the available traction can be measured. The test results can demonstrate objectively what corresponding increase or decrease in traction would have been experienced by the claimant. This can then help answer questions about liability and whether or not a slip and fall oc-curred due to occupiers’ negligence or because of something inherent to the injured party.

Sintra Engineering has been retained to investigate many slip, trip and fall incidents, most commonly pertaining to the con-dition of the ground surface and issues related to a surface's slip resistance. If you are handling a file that involves a slip, trip or fall incident, or if you have further questions regard-ing slip resistance testers, please contact Sintra Engineering at 1.877.244.6251.