Really? OSB Sheathing Blamed in Building Collapse Due to 86 mph Wind!
You may recall the Brier Creek Multifamily building collapse (video below) due to a straight line wind gust of approximately 86 mph that went viral in early 2014. This generated significant media attention, which you can relive via the links found at the end of this article.
It goes without saying any natural disaster, like a tornado or hurricane, causes severe stress on buildings. Hence, to state in an article or even imply that OSB is the cause of a collapse is disingenuous at best (sensationalizing for promotional gain), and unprofessional at worst.
Some of the questions that need to be honestly addressed follow, but certainly are not limited to:
- Was the building built to code?
- If not, what were the as built conditions?
- Which aspects of the structure were built to code?
- Which were not?
- What is the cause/effect analysis for each code compliant and each non-code compliant condition?
- Is there any possibility of being able to benchmark performance? For example:
- Does one building built identically to another perform differently?
- Why did it perform differently?
- Different winds?
- Different methods of connections?
- Different building orientation?
- Different window and door conditions?
There will be many reports on high wind event damage in the forthcoming years. Some will be credible, others may use sensationalism to denigrate one product or application to promote a negative bias in the market. Most of the time if one looks at who the author of the article or report is one can quickly discern if there is an evident conflict of interest.
The articles below could certainly say that OSB sheathing was the bad actor. That would be completely sensational because, while it may look that way on the surface, in-depth analysis immediately suggests something else went very wrong here.
As one can see in the video, it is difficult to learn much, if anything, from a building that is partially or totally destroyed. For this reason, damage assessment and any assessment from a damaged building must be limited. In most cases, engineers can point to one of several common weak links as the cause of structural failure and damage. Observations of adverse building performance in high wind events typically find that any structural failure is often due to a lack of adequate connections. A continuous load path, the flow of forces through a structure and the connections from the roof coverings and siding (exterior cladding) to the framing and to the foundation, must be provided for reliable building performance.
Typically, there are several commonly observed reasons for failure: these included using toenails without metal connectors for the roof-to-wall connection, using pins without anchor bolts to attach walls to the foundation, poor fastening and the use of the wrong nail type and poor edge distance connections for exterior wall and roof sheathing products like OSB, and breaches due to failure of windows, garage doors, or cladding/wall systems that result in catastrophic failure.
It is obvious that construction implementation is the key to satisfactory building material performance – i.e. not following the requirement to use an 8d common nail at a 3/8” edge distance in a 6” o.c./12” o.c. pattern may cause structural performance issues. Obviously, using more nails and providing close attention to all connecting systems that make up the load path is essential.
The most important outcome of poor building performance in a high wind or seismic event is that no one gets hurt, the construction industry continues to learn and evolve; and design and installation best practices improve. The entire construction industry will greatly benefit from not believing anything those who wish to be sensational choose to say. The goal should be to help those that have a positive focus on innovation and best practice improvement.
Additional Thoughts from Evaluating Media Reporting and Videos
The following are a series of reports that describe the media and a University of Florida assessment. It is pretty clear from watching how the building collapses that it is highly likely that the OSB sheathing was not fully attached. It is also likely that more complete fastening was going to be done at the time of building wrap application, which had not completely happened yet for the building in question. If this is not the case, why are the other buildings standing? It seems to make common sense that if all buildings were performing under the same installed condition they would react to the same wind in the same manner. University professors can make assessments which are merely opinions that may be quite incorrect (see item #7 below). There may also be professors that “consult” to undertake testing and yet do not use a science based methodology to provide common apples-to-apples benchmark comparisons and then show distorted pictures in the hope that lay people are not critically discerning. Clearly, their hope is to generate sensational conclusions that benefit the folks paying for the consulting.
- Builder starting over on storm-damaged condos in Brier Creek -- Toll Brothers, the Pennsylvania-based company that is building the project, known as the Cottages at Brier Creek, said in a statement that the building was not far enough along in its construction to withstand the extreme winds that knocked it down. Windows, metal framing and other structural supports were not yet in place in the building. By contrast, an adjacent building that did have those features is still standing.
- OSB SHEATHED/BRACED CONDO COLLAPSE VIDEO GOES VIRAL ... A video (posted below) of a condo building in the Brier Creek area of Raleigh, NC collapsing has gone viral.
- Building under construction collapses in Brier Creek - YouTube https://www.youtube.com/watch?v=5t9MpNTSbYg
- North Carolina Condo Building Collapses During Storm ... www.thestructuralengineer.info/.../88-north-carolina-condo-building-collapses-during...Jan 16, 2014 - Strong winds cause North Carolina condo to collapse Source: ... Toll Brothers, the company constructing the Brier Creek condominium building, ...
- Engineer: Brier Creek building collapsed while awaiting Raleigh ... www.wral.com/engineer-brier-creek-building-collapsed.../13325762/ Raleigh, N.C. — A condominium building in Raleigh's Brier Creek neighborhood collapsed during a Jan. 11 storm because crews were waiting ...
- Must see video: Buildings under construction collapse in Raleigh, NC ... www.statter911.com/.../must-see-video-buildings-under-construction-collapse-in-ralei...This is video captured by professional wildlife photographer Ed Braz of apartments under construction at The Exchange at Brier Creek in ...
- Horror as building collapses into North Carolina backyard during ...www.dailymail.co.uk/.../Horror-building-collapses-North-Carolina-backyar... Braz, of Brier Creek, took video of an entire section of a ... No injuries: Thankfully no one was inside the collapsing buildings, and no one ...
- Wind Damage to Brier Creek Condos - Wind Hazard Damage ... windhazard.davidoprevatt.com/.../11-January-2014-Brier-Creek-NC-Condos-Colla.pd...This report focuses on the wind damage to the Brier Creek Condominiums near .... The collapsed buildings appeared to consist of two, 3-story ...