Roof collapse investigations: Engineers Say Codes Adequate

snow collapses roof deck Following on last week’s story about green roofs, including one which collapsed under a weight of snow and ice, engineers speaking to the ENR have stated that Codes are adequate, but that they may need to be adjusted in certain situations:

[E]ngineer sources for this article say existing building codes are adequate if designers allow for a factor of safety. But Levy [Matthys Levy, chairman emeritus at Manhattan-based Weidlinger Associates]  recommends designers make proper allowances for snow accumulation such as when designing roof structures near parapet walls, especially those that are four feet or higher.

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Multi-level roofs with steps instead of roof flashing can also be problematic with snow accumulation on a first-story portion, for instance, piling up against the second story, Levy says. “It’s best to avoid stepped designs unless you design for them,” he says. While an average of 40 psf may be adequate for designing most of a roof, designers should allow 60 psf to 80 psf for the parapet wall, he says. And mountainous regions may require twice as much strength, he says.

Garrick Goldenberg, professor of structural engineering at Wentworth Institute of Technology in Boston and chief structural engineer at Chappel Engineering Associates in Marlboro, Mass., said that while state building codes address snow drifts with requirements for the shape and slope of a roof, this year’s record snowfalls and ice accumulation with little thawing has led to a greater number of collapses.  In sampling snow at Chappel Engineering in early February, Goldenberg says his group found that even two feet of freshly fallen snow or more totaling 16 to 20 lb/sf was not a danger to buildings. On average, people assume fresh fallen snow produces eight pounds of pressure on a roof per square foot.

However, invisible loads caused by accumulation of ice have been a serious problem since ice weighs 7.5 to 8 times more per cu ft than snow. “In many cases, even before reaching two-foot snow loads, we were in excess of 30 pounds because of the ice,” he claims.

For more, go to the ENR full story: Ice, Snow Take Toll on Northeast Roofs, But Engineers Say Codes Are Adequate.

What are your thoughts about current Codes, in light of the many collapses in the Northeast and Midwest?  Legally, does designing to Code, but failing to take into account likely weather events, make your design deficient?  I’ll post some of my thoughts in a subsequent post, but share yours below.

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 Photo: “Deck roof collapse”   by Derek K. Miller via Creative Commons license/Flickr

A tale of 2 green roofs

green roof

Chicago City Hall’s Green Roof

Two commercial “green” roofs have been in the news this week.   One involves a collapse; one involves energy savings.

Green Roof Collapse

The green roof at the Aquascape, Inc. warehouse in Illinois collapsed over the weekend, likely due to melting snow and ice.   A 50 foot wide section of th 256,000-square-foot roof (allegedly the largest sloping green roof in North America) collapsed on Sunday, although no injuries were reported.  A team of structural engineers from the building’s design firm is investigating the cause.  As noted in a company press release, St. Charles, IL, where Aquascape Inc’s head office is located, had been recently hit with a major snow storm where 20.6 inches of snow had fallen in less than 24 hours, followed by above freezing temperatures causing a quick thaw.  An ice damn at the base is suspected to have backed the water up over the parking structure causing its collapse.

Solar Roof goes “live”

While Aquascape’s engineers are investigating their roof collapse, there is some good green roof news closer to home.  Raleigh-based marble company David Allen Company has recently “flipped the switch” on a photovoltaic solar energy facility that  it claims is one of the largest rooftop photovoltaic systems in the Triangle, with  700 solar modules covering 23,000 square feet of the rooftop of the company’s warehouse.  The company hopes to offset at least 35% of its current electrical costs, and sell energy to Progress Energy as well, according to Triangle Business Journal.

Legal Implications related to Roof Design?

Both of these roofs bring up legal issues.  Was the Aquascape green roof designed appropriately to accommodate loads in a winter climate?

With so many roof collapses this winter (including, of course,  the Minneapolis metrodome) , is there, or should there be, a duty on the building’s owner/maintenance crew to proactively remove snow accumulations?

For new solar roofs, such as at David Allen Company, who assumes the risk if the expected cost savings are not realized?

Based on the sheer number of roof collapses this winter, and the number of green projects growing steadily, there is sure to be some litigation addressing at least some of these issues in the near future.  Stay tuned.

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Photo Courtsey Wikipedia/Creative Commons license 

Can a designer limit his liability to his fees for service?

Architects and engineers (and the owners/contractors with whom they contract) often wonder whether limiting liability language is enforceable.  The answer, as in much of construction law, is very much dependent on what state’s court will be interpreting the contract.  Some states allow such limiting language, and others do not.  Josh Glazov’s Construction Law Today blog recently tackled the enforceability of such provisions in the context of a recent Illinois case, in which the Illinois court found such limitations perfectly acceptable, so long as they (1) are not “unconscionable” and (2) do not violate public policy.

sign: proceed at own risk
 

North Carolina takes a very similar approach to such limitations of liability.  Here, so long as the limitation of liability is not also an agreement to be liable for the other party’s negligence (which is barred as against public policy), such a limitation of liability is enforceable.  A case discussing this issue from the engineering perspective is Blaylock Grading Co., LLP v. Smith et al, 189 N.C. App. 508, 658 S.E.2d 680 (2008).  In that case, a surveying engineer limited his liability, via contract, to $50,000.  The Court, citing an earlier state Supreme Court decision, ruled that the limitation was valid and enforceable:

People should be entitled to contract on their own terms without the indulgence of paternalism by courts in the alleviation of one side or another from the effects of a bad bargain.  Also, they should be permitted to enter into contracts that actually may be unreasonable or which may lead to hardship on one side.  It is only where it turns out that one side or the other is to be penalized by the enforcement of the terms of a contract so unconscionable that no decent, fairminded person would view the ensuing result without being possessed of a profound sense of injustice, that equity will deny the use of its good offices in the enforcement of such unconscionability.  Id. at 511, 658 S.E.2d at 682.

Is this rule absolute?  Clearly not, as the above quote indicates.  Unconscionable limitations will not be enforced.  Moreover, a third party, not subject to the contractual terms, is free to sue in negligence.  But as between the contracting parties, such a limitation on damages can be a powerful tool to minimize exposure to risk.

Questions about limitations on liability?  Comment below or drop me a line.  And be sure to sign up for email delivery of blog posts directly to your inbox.

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Photo:  “Proceed at own risk” by Dave Nicoll via Flickr/Creative Commons license 

Why should a Designer worry about the Contractor’s insurance issues?

Insurance: not just for Geckos anymore

You may wonder why you, as the designer of record, should care about the insurance coverage of the contractor on your construction projects.  After all, that is an issue between the contractor and the owner, right?  Not so fast.  Recent court cases addressing whether or not commercial general liability (CGL) policies provide insurance coverage for a contractor’s poor workmanship can create problems for architects and engineers.

Since architects and engineers usually have errors & omissions policies (and you do have E&O coverage, right?), they may be the only ones with “deep pockets” should litigation arise over construction defects.   The take-away?  It *is* your business to make sure that the contractors on your projects have sufficient resources to pay for construction defects.  It is also in your best financial interest to ensure that you are only working with top-notch, quality contractors. 

The insurance folks at Victor O. Schinnerer & Company recommend:

More than ever, design professionals should use sound risk management practices when selecting new projects—especially condo projects. Design professionals should insist upon providing full construction phase services and should urge developers to retain contractors using qualifications-based selection procedures. 

I wholeheartedly concur.

Questions?  comments on how Builder CGL policy issues are relevant to your design risks?  Drop me a line.

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Photo: “Geico Gecko”  by Scott Kinmartin via Flickr/Creative Commons License.

Root canals & Lawsuits: two things to avoid (Law Note)

man flossing

 No one (with the exception of sadistic dentists)  likes root canals, and no one (except lawyers) likes lawsuits.  In the same way you can prevent (or limit) the need for root canals through proper flossing habits, you can limit the number of lawsuits you need to be involved in if you include everyone you should the first time around.  For those involved in filing construction liens, this means that when you perfect a lien by filing the lawsuit, be sure you include everyone you need to include.  A recent North Carolina Court of Appeals case demonstrates this principle in full living color.

In Lawyers Title Insurance Corp. v. Zogreo, LLC, __ N.C. App. __ (November 16, 2010), two contractors filed and perfected valid liens on a piece of property.  They did not include, in the lawsuits to perfect the liens, the banks which had given funds to the property owner after they first began work on the property.  The Court held that it was entirely proper not to include the banks (who held deeds of trust on the property to secure their loans); however, by the contractors’ failure to include them, they were forced to later litigate priority issues with the banks.  This is because “if a subsequent encumbrancer is not joined [in the underlying lien perfection lawsuit], he is not bound by the judgment in the action between the contractor and the owner.” 

In other words, even though they filed proper liens, filed the lawsuits timely, and even won final judgment in those lawsuits, because they did not include the banks, the banks were free to start a new action, which they did in this case.  The banks also obtained an injunction to stop any judicial sale of the property until priorities could be established.

Moral of the story? It is better to include all subsequent encumbrancers (i.e., the banks) when perfecting a lien.  It’s not required, but it is better practice.  (And flossing your teeth isn’t required, either).   After all, who wants a root canal, or, in this case, to re-litigate your right to be paid money in yet another expensive lawsuit?  When it comes to root canals and lawsuits, fewer is better.

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Photo: Day One Hundred Fifty-One by Eric Mesa via Flickr/Creative Commons License