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Written by Shelby O. Mitchell on . Posted in Industry Articles.

Restructuring Specifications: Improving Stability and Durability of Structural Concrete With ACI 301-16

What can be done to help specifiers and contractors create the most stable, durable, and resilient concrete structures possible? This challenge inspired the industry professionals responsible for updating an American Concrete Institute (ACI) standard over the summer. (ACI 301-16 is available in print and digital formats at www.concrete.org.)

Every five years, ACI 301, Specifications for Structural Concrete, is updated to complement the newest version of ACI 318, Building Code Requirements for Structural Concrete. (ACI 318-14, Building Code Requirements for Structural Concrete, has been completely reorganized to reflect the designer’s perspective. More details are available at www.concrete.org/tools/ACI318.) During the most recent review cycle, ACI 301 Committee on Specifications for Structural Concrete not only updated technical requirements, but also created a more user-friendly reference specification for nearly all forms of structural concrete.

The committee’s approach was twofold. Specific wording was one area of focus: removing redundancies, making language more self-explanatory, and improving definitions of terms. The specification also had to maintain a broad scope, since ACI 301-16 is used across a wide range of climates, geographic areas, and social conditions around the world.

PROVIDING CLARITY

One way of encouraging specifiers and contractors to adopt a specification is to make it easier to understand.

“We spent a lot of time cleaning up the language to make it more clear for the user,” says Michelle Wilson, the committee’s chair (and director of concrete technology for the Portland Cement Association [PCA]). “This is a contract document written in mandatory language, so it’s very important to remove wording that is confusing or subject to interpretation.”

The committee clarified many commonly used terms. ‘Architectural concrete,’ for example, is defined in the specification as:

concrete that is typically exposed to view, is designated as architectural concrete in contract documents, and therefore requires care in selection of the concrete materials, forming, placing, and finishing to obtain the desired architectural appearance.

Many provisions have been spelled out to clearly indicate their intent. For example, the requirement for water used for curing concrete previously stated:

Unless otherwise specified, water complying with the requirements for ASTM C1602/C1602M [Standard Specification for Mixing Water Used in the Production of Hydraulic Cement Concrete] is acceptable as curing water.

ACI 301-16 now reads:

Unless otherwise specified, do not use seawater or water containing substances that will discolor or impair the durability of a concrete member.

Throughout the specification, consistent language differentiates between required and optional provisions. The phrase “as specified in the contract documents” indicates a mandatory checklist item and tells specifiers they must take action. “Unless specified otherwise” means something is optional. This flags items specifiers may want to review, and tells contractors alternatives may be available. This ‘trigger language’ has been reduced from around 30 different words and phrases to just five or six in the new specification.

REFLECTING REALITY

Given ACI 301 is used around the world, it is available in metric units, and a Spanish version will be published this year. However, ensuring the specification is truly applicable anywhere from Peru to Canada takes more than simple translation.

“ACI 301 is a conservative specification that covers many different applications. There are some restrictive provisions that are intended to provide structural, stable, and durable concrete in service,” says Wilson. “However, there are several contractor-friendly options that ensure we’re not restricting the builder’s ability to decide means and methods.”

In fact, many changes to ACI 301-16 are performance-based to better reflect standard industry practices. Concrete slump, for example, is no longer defined by the specifier. Contractors must choose, to a specific number of inches, the slump best-suited for their given application, then place concrete within the specified slump tolerance.

Previous versions of ACI 301 also included a checklist of submittal items, which was cumbersome for contractors and specifiers to utilize. Submittals are now defined in the body of the specification, so one does not need to jump between the body and a checklist at the back of the document.

DRAWING ON INDUSTRY EXPERTISE

As a specification rooted in actual jobsite practice, ACI 301-16 reflects the complexity of concrete construction—sometimes there is no straightforward answer.

“We took on several controversial subjects and weren’t always able to reach consensus,” says Jim Cornell, general superintendent at Beck Group (Fort Worth, Texas), and past chair of the ACI 301 Committee.

Cornell says, for example, descriptions of what may qualify as mass concrete in ACI 301-10 were “bulky, non-specific, and open for interpretation.”

After a concerted effort to refine the standard, the committee was unable to reach a better solution. In the end, the cementitious materials content—300 kg/m3 (660 lb/cy)—which had led to much debate, was simply removed.

New to ACI 301-16 are specification provisions addressing alkali-silica reactivity (ASR). ACI Committee 301 expended considerable effort on writing requirements providing for the long-term durability of structures, using the best, most current knowledge of test methods and mechanisms of failure. The committee focused on developing requirements usable across many geographic locations, despite the set of challenges each region presents to providing ASR-resistant materials for concrete. The published specifications provide clear direction for the testing of aggregates, as well as a choice of performance and prescriptive approaches for reducing the risk of ASR.

In other instances, committee members referred to specifications generated by industry associations outside of ACI.New to ACI 301-16 are specification provisions addressing alkali-silica reactivity (ASR). ACI Committee 301 expended considerable effort on writing requirements providing for the long-term durability of structures, using the best, most current knowledge of test methods and mechanisms of failure. The committee focused on developing requirements usable across many geographic locations, despite the set of challenges each region presents to providing ASR-resistant materials for concrete. The published specifications provide clear direction for the testing of aggregates, as well as a choice of performance and prescriptive approaches for reducing the risk of ASR.

“Certain topics may not have been covered in-depth by ACI 301 or other ACI specifications before, but other industry experts have developed comprehensive mandatory-language reference documents,” says Cornell.

ACI 301-16 now includes external references for topics such as reinforcement and post-tensioned concrete.

The specification refers contractors to a new document from the Concrete Reinforcing Steel Institute (CRSI) to determine proper support for welded wire reinforcement (CRSI RB4.1 [2014], Supports for Reinforcement Used in Concrete, covers the design, use, and material requirements of various reinforcement supports used in concrete. For more information, visit www.crsi.org.), as well as a specification published by the Post Tensioning Institute (PTI) for grouting of bonded tendons. (PTI M55.1-12, Specification for Grouting of Post-Tensioned Structures, provides minimum requirements for the selection, design, and installation of cementitious grouts and ducts for post-tensioning systems used in concrete construction. Additional information can be found at www.post-tensioning.org.)

MANDATORY VERSUS OPTIONAL PROVISIONS

ACI 301-16 is organized into two parts, distinguishing basic items always required for structural concrete construction from those that may be required on particular projects. When an architect or engineer cites ACI 301-16, the document is intended to be adopted in its entirety into the contract documents. However, specifiers have the latitude to change some of its provisions.

The first five sections cover general construction requirements for contractors performing cast-in-place structural concrete work and placing slabs on-ground. These include requirements relating to formwork, reinforcement, concrete materials, and means and methods for placement and transportation.

The remaining nine sections are devoted to other structural concrete applications, which may or may not pertain to specific projects:

  • architectural concrete;
  • post-tensioned concrete;
  • mass concrete;
  • lightweight concrete;
  • industrial floor slabs;
  • shrinkage-compensating concrete;
  • tilt-up construction; and
  • both architectural and structural precast concrete.

These specialty provisions have been expanded in ACI 301-10, so each is discussed in a similar level of detail. Specifiers are required to indicate where any of these applications are used in a project.

At the end of the document, specifiers will find two checklists spelling out which provisions within each section are mandatory and which are optional.

“As a designer prepares contract documents referencing ACI 301, he or she can run through the checklists to ensure the right provisions are incorporated into the project,” according to Cornell.

The list of optional provisions serves as both a reference and a reminder.

“When designers review the optional checklist items, they may consider enhancements to the project that they hadn’t thought of before,” says Cornell. “It also lets contractors see potential avenues of accomplishing the work differently, and changes or improvements that could be made via substitution or a substitution request.”

CONCLUSION

With clarified language and structure, ACI’s newly updated standard, Specifications for Structural Concrete, provides a straightforward, contractor-accessible reference architects and engineers can apply to any project involving structural concrete. In addition to being cited in project specifications, ACI 301-16 requires contractors to keep a copy of the ACI Field Reference Manual—which includes the most recent structural concrete specifications—in the field office of any project where ACI 301 is specified. (The ACI Field Reference Manual is a compilation of documents incorporating ACI 301-16 and additional ACI documents on measuring, mixing, transporting, and placing concrete, concrete pumping methods, hot- and cold-weather concreting, consolidation, and concrete formwork.)

This year, ACI will also be publishing updated specifications designed to improve concrete testing and inspection services.

This includes:

  • ACI 311.6, Specification for Ready Mixed Concrete Testing Services; and
  • ACI 311.7, Inspection Services Specification for Cast-in-place Concrete Construction.

Shelby O. Mitchell is a freelance writer for the construction industry, and former editor of The Concrete Producer magazine. She is based in Berwyn, Illinois. Mitchell can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

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Written by Mike Christy on . Posted in Industry Articles.

UA Architecture Students Do Their Level Best

University of Arizona architecture students, from left, Lucy Nielsen and Jared Spear congratulate each other after successfully leveling a block. On Tuesday, groups of students in Ray Barnes’ Building Technology Materials and Methods course designed and constructed their own masonry walls at Superlite Block, 2200 W. Gardner Lane. The groups of four students completed the walls, limited to 32 square feet, with volunteer help from employees of Sun Valley Masonry. The program and partnership with Superlite Block is in its 16th year.

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Written by Steve Janoski on . Posted in Industry Articles.

Tedesco Demands Fire Code Changes In State of The County Speech

HACKENSACK — Bergen County Executive James J. Tedesco III had a straightforward message for state officials Monday: Change the building codes regarding lightweight wood construction, the use of which has been blamed for two massive residential fires in the last three years, including one in Maplewood this month.

Do it, Tedesco said. And do it now.

“We cannot wait any longer, because people are going to die, and buildings will continue to burn to the ground,” said Tedesco, a 41-year Paramus firefighter. “By simply changing a few words and a few sentences, officials can dramatically improve the safety of all those that will occupy units constructed with lightweight wood — and save lives.”

Tedesco made the remarks to a packed house at 2 Bergen County Plaza during his annual State of the County address, his third since taking office, which the Democratic executive otherwise used to review county efforts to improve education, encourage cultural acceptance, and create a parks master plan. The master plan, still in development, would guide the evolution of the park system through 2040, he said.

He also urged the state to finally fund a long-planned extension of the Hudson-Bergen Light Rail into Bergen County. This, he said, would improve commuters’ lives and revitalize municipalities along the proposed route. The estimated $900 million extension of the line that runs from Hoboken to North Bergen would add stops in Ridgefield, Palisades Park and Leonia before ending in Englewood.

Bergen residents are eager to see the same development that has occurred along the Hudson County sections of track, he said.

But the executive saved his most fervent rhetoric for the ongoing fire code issue.

Latest AvalonBay fire raises questions, concerns

Maplewood fire raises call for change to building codes

Tedesco proposed a coding change that would mandate the installation of sprinklers in concealed spaces. This, he said, would have helped suppress the enormous January 2015 apartment building fire at the Avalon at Edgewater. The blaze destroyed a 240-unit building, displacing 1,000 people and leaving about 500 homeless.

He also called for the installation of masonry fire walls that extend to the roof, which would compartmentalize the building and prevent fires from burning through common attics or floors.

Tedesco is not alone in his crusade — there were calls statewide to revise fire codes after the Edgewater disaster. But progress stalled, and despite the introduction of six bills by state legislators from both sides of the aisle, no code changes have been made. None of the committees given the task of overseeing the bills has even given them a hearing.

But the chorus has grown again in the wake of the Feb. 4 Maplewood blaze, which destroyed an under-construction apartment complex being developed by AvalonBay Companies Inc. The same company built the Edgewater complex.

Despite Tedesco's passion for code revisions, it is unclear how much he can do at the county level. The state's building code can be amended through administrative review by the Department of Community Affairs, or changed through the legislative process. Both are well beyond Tedesco's reach.

AvalonBay voluntarily increased fire safety measures after the Edgewater blaze, adding more sprinklers and fire walls to new projects. But Tedesco said government mandates are necessary nonetheless. In the speech he demanded immediate action and said the legislative delay is indicative that something is “terribly wrong.”

“We can’t wait anymore. Thank God we haven’t lost any lives, but time is running out,” he said afterward. “This is very doable, very quickly.”

Tedesco’s biggest cheerleader in his fire code fight might be Michael McPartland, the Democratic mayor of Edgewater, who was three weeks into his first term when an unlicensed maintenance worker accidentally sparked the Avalon fire with a blowtorch.

McPartland called Tedesco’s speech “powerful” and enthusiastically agreed with his proposals.

“They’re not draconian moves that need to be done. It’s very easy, and very economically feasible,” McPartland said. “Jimmy [Tedesco] is going to be on a mission to do it, and I’ll go with him. Trenton, Washington. Wherever.”

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Written by Ed Davenport on . Posted in Industry Articles.

Cheaper, Faster, Better

Zaragon Place - A Prime Example

 

“If it’s not cheaper, faster, better, don’t come to the table” has been the construction industry credo as long as I have been in the masonry business, some 35 years now. And “everyone knows that you can never have all three.” Only two are possible. But, for the last 35 years and long before that, loadbearing masonry has exceeded the cheaper, faster, better to be the cheapest, fastest, best solution to many building types. Yes, all three. And Zaragon Place, a 100,000 sf, 10 story residential building adjacent to U of M with 248 bedrooms and 66 living units above ground floor retail and underground parking demonstrates this.

Zaragon Place, Ann Arbor

ARCHITECT Neumann/Smith Architecture, Southfield
ENGINEER Desai/Nasr Consulting Engineers, West Bloomfield
CONSTRUCTION MANAGER O’Neal Construction, Ann Arbor
TESTING ENGINEER SME, Plymouth
QUALITY CONSULTANT Mariano “Skip” DiGiovanni, IMI
MASON CONTRACTOR Davenport Masonry, Holt
MASONRY MATERIALS Advanced Building Products, Dow Cavitymate, Glass Block Sales, Grace Construction Products, Grand Blanc Cement Products, Masonpro, St Marys Cement, Solomon Colors, Superior Materials, Superior Precast Products, Williams Products, Wire-Bond
MASONRY EQUIPMENT TNT Equipment

Masonry has forever been the façade of choice. Steel and concrete production ramped up during WWII to meet increasing demand. After the war, the increased production flooded the construction market.

CHEAPER

Today, with the ever increasing costs of steel and delays of up to 14 weeks in procuring it, the paradigm shift is clearly back to loadbearing masonry. Loadbearing masonry is cheaper, roughly only $30/sf of exterior wall surface. Whereas steel systems run $40/sf. The foundation cost is also greater with steel. It is minimized with masonry. Masonry inherently brings a fire rating of up to four hours. Steel needs to be fire proofed. Masonry is a finished product. Steel needs metal stud/ drywall to be installed and painted.

FASTER

Concrete masonry units (CMU) are readily available from 28 block manufacturing plants throughout Michigan. There is NO wait for loadbearing CMU. Construction on your project can begin immediately. Schedule is enhanced when trades are minimized. We laid the brick façade up floor by floor right behind the block. When steel is involved, the ironworkers, carpenters and fire proofers need to be sequenced.

We could lay up CMU 10 for each story — all bearing walls — in just four days. Precast plank took 3 days. Every seven days another 10 of loadbearing masonry and precast plank floor went up.

Exposed raw CMU was the finish on the inside juxtaposed against high-end furnishings for a crisp, durable, modern take on student housing.

BETTER

Loadbearing masonry is likely the most cost effective, schedule sensitive, fire proof system to use for a building greater than twostories in which people sleep.

Loadbearing masonry may not lend itself to retail with an open floor plan. So the art of the mixed-use facility is using concrete frame to the height of the second floor and loadbearing masonry to the top of the building. For the residential portion, the repetitious floorplan, story upon story, lends itself to the loadbearing masonry with hollow core precast plank flooring. The Excalibur Hotel in Las Vegas is a prime example — 240 tall and all loadbearing masonry.

Brick and block insulated cavity wall brings a high performance R-Value of 23.85, which equates to energy savings exceeding 200% of the ASHRAE standard. This energy efficient cavity wall consisted of 8˝ CMU, 21⁄8˝ Dow CavityMate Ultra with an R-Value of 7.5 per inch, airfilm, 2˝ air space and 4˝ exterior brick. With the current oil crisis, putting buildings and cars in competition for available energy, we need to address the shortage and begin producing walls with higher R-Values. The owner requested that the energy efficiency of the building be maximized. Masonry met the challenge.

MASONRY ALTERNATE DESIGN

Zaragon Place was originally designed as a steel frame/metal stud backup structure. We saw a potential opportunity for loadbearing masonry to be used as the structure and back-up walls, so we put together a voluntary alternate. Tim Stout, project estimator from construction manager O’Neal Construction, saw the possibilities with our voluntary alternate and pursued its merits to give the owner a more durable building that will last forever, with increased energy efficiency and decreased sound transmission.

Elevator shaft and stairwells were originally designed as loadbearing CMU; lintels and building structure were converted to CMU. It is never an easy/seamless task to convert one design to another. I could tell from the first time we met with the team from O’Neal Construction, Neumann/Smith Architecture and Desai/Nasr Consulting Engineers that the conversion was possible. They had a “can do” attitude. Neumann/Smith and Desai/ Nasr are well versed in loadbearing masonry; they have designed this system in numerous types of buildings.

Both Neumann/Smith and the partners of Zaragon Corp, developers from Chicago who are both alumni of U of M, were thrilled with the possibility of a masonry building that came in net net, saving both dollars and construction time. Joel Smith, president of Neumann/Smith Architecture, complimented Desai/Nasr on their heroic effort to redesign the engineering within 30 days prior to construction. “The incredible turnaround was quite impressive. With the loadbearing masonry design, we were able to give our client a better building with better dimensioning. There are no columns. We have the aesthetic of block and sound isolation between rooms.”

“We converted this project with masonry design completed in just about two weeks and delivered a preliminary masonry bid package,” mentioned Jay Desai, President of Desai/Nasr Consulting Engineers, “then followed up with remaining details a week after. Today, with the new total building Ram Advanse loadbearing masonry software we are using, we can shorten this time frame for redesign. Major advantages in the new design were the elimination of columns freeing up space for furniture and living within the units and reducing the size of the partition walls because masonry inherently absorbs sound and we did not have to add another material to do that task. Add to that the budget and time savings. Bearing walls also served as shear walls for both wind and seismic lateral loads in the East-West direction. Shear walls in the North-South direction were not symmetrically located, resulting in torsion in the floor diaphragms. These forces were transferred to the EastWest walls through shear forces in the floor diaphragms. We checked all the grout keys between the hollow core planks to make sure that the in-plane shear stresses were within the allowable limits. Also, because of the parking underneath, all the walls could not be extended to the foundations, requiring concrete transfer beams at the second level spanning between concrete columns,” said Desai.

“This project was such a success in large part because of the close communication and cooperation of the architect, engineer, testing engineer, construction manager, quality assurance consultant and mason contractor. At the preproduction meeting, an agenda was created. The crew followed everything agreed to in achieving good quality construction. The masons took great pride in the quality of their work.”

Kudos go to this team — especially Mark Steinhobel, PE, of Desai/Nasr, Pat Macoska, RA, of Neumann/Smith Architecture and Tim Stout of O’Neal who had the willingness to work together and try a new system.

LESSONS LEARNED

Many lessons were learned in constructing this building. There is always a learning curve whenever you do something for the first time.

Minimizing the quantity of subcontractors and trade disciplines creates a distinct advantage, especially when job site space restrictions exist as in the heart of Ann Arbor. It may make sense to include façade steel, precast hollow core plank and perhaps other precast concrete elements in the mason contractor’s package for optimum seamless schedule efficiency.

Training, certifying and counseling made available through Bricklayers and Allied Craftworkers (BAC) 9 and International Masonry Institute (IMI) was another very critical element to the success of this project. Without their support, this project would have been much more difficult.

Skip DiGiovanni, as quality assurance advisor with BAC-1 Detroit, implemented the hands-on technical reinforced masonry training with the assistance of Pete Loughney, CPC, AIC, Michigan Director of the International Masonry Institute. Tradespeople benefit from refresher training in loadbearing masonry. It may not be the wall system they are most used to. But it will become much more common with the paradigm shift.

Once they understand how this engineered wall system is structurally designed, it makes more sense. Productivity and speed increase. Costs go down. Execution becomes more perfect.

A team attitude prevailed with the special masonry inspector, the structural engineer and representatives from the construction manager and architect, all in attendance. Special accolades need to go to Hayder Al Ailal, EIT, of Soils and Materials Engineers (SME). He was the special masonry inspector and critical member of the team. He worked with the crew to assure compliance. His proactive behavior and no “Monday morning quarterbacking” produced amazing results.

Loadbearing masonry should prove to be the fastest system to construct housing type structures. There is much we can, as an industry, do to improve speed at construction and reduce costs.

The masonry industry is in the process of developing a series of standard details. As example, “what is the simplest, least expensive, fastest way to install relief steel shelf angles to a loadbearing masonry structure?”

Another way to reduce costs and improve speed of construction is for the mason contractors and their tradespeople to win the respect of the engineer. When engineers believe in us, the quantity of reinforcing need not be overdesigned. Special masonry inspection and training are ways to improve the engineer’s confidence. CMU is reinforced in grouted cores. The centers of the reinforcement typically are spaced further apart as the building rises taller.

In the last 30 plus years, many multi-story buildings were constructed with a frame of structural steel or structural castin-place concrete. Exterior backup used metal studs and gypsum drywall. With the structural frame costing $8–10 per exterior surface sf and the metal stud/gypsum wall cost being comparable to masonry backup, it is logical and quite cost effective to use the masonry wall as the structure and enclosure, eliminating the additional cost of $10/wall sf.

All lead time for structural steel can be eliminated, as masonry units for a loadbearing system are readily available. Depending on the size of the building, it is feasible to cycle a floor of loadbearing masonry construction in just 7 working days.

BEST

Loadbearing masonry is one material with inherent qualities enabling it to play lots of roles bringing great added value to every project.

  1. High performance wall systems offer single-source accountability.
  2. Structurally, it carries both gravity and lateral loads.
  3. Thermally, as one or more components of the insulated masonry cavity wall system, it can contribute up to an R-34, 350% of ASHRAE requirements, saving nearly 70% of energy costs year after year after year for the building’s entire life span — and for masonry that easily exceeds 100 years.
  4. Thermal mass efficiency.
  5. Acoustically, when CMU cores are filled with sand, grout, foam insulation or dried and processed slag, it dampens sound. CMU mass absorbs the lower frequency. When chiseled-, rock- or split-face, sound waves are reflected enhancing acoustical performance.
  6. Masonry stops fire cold with a fire resistance rating of up to 4 hours, allowing those contained in the building safe egress.
  7. Masonry is inorganic, therefore providing no food source for mold growth, contributing to cleaner air and a healthier indoor environment.
  8. Masonry is finished on all sides and needs no paint, coating or sealant. If one is desired, low VOC options are available. Again, contributing to cleaner air and a healthier environment.
  9. Masonry is durable, withstanding abuse of equipment, vehicles and occupants.
  10. Masonry wall system is more effective for anchoring stone.
  11. Masonry is strong, surviving severe weather conditions and intentional acts of violence. It can be washed down and disinfected after a flood. Often the only part of a home left standing after a hurricane or tornado is the masonry part of the house, the fireplace and chimney. Even the masonry Pentagon with its inherent arching action survived the Boeing 757 jet crash impact without collapse. It merely left a hole, while the remainder of the building remained in tact. That is structural redundancy!
  12. Initial cost for masonry, the premier wall system, is lower than other systems.
  13. Because masonry stands up to fire and to severe weather, vandalism and acts of violence, its survival rate is higher and its insurance premiums are lower. A big benefit to the owner over the life of the building.
  14. Net operating income of a real estate investment trust is greater when the expenses of insurance, maintenance, energy are minimized.
  15. Masonry requires little maintenance over its lifetime — maybe a little tuckpointing after 30–50 years. And a cleaning after 50–100 years. Greatly reducing its life cycle costs, a huge benefit to the owner.
  16. Masonry is sustainable. In other parts of the world, masonry remains standing after thousands of years. In Michigan, it dates to the mid 19TH century. Today, adaptive reuse is prevalent for masonry buildings that have outlived their original use. 
  17. Masonry is green, environmentally friendly, LEED compliant. Besides all of its attributes noted above, block and brick often use recycled content keeping it from landfills and conserving precious natural resources. Masonry materials, in turn, are 100% recyclable. Materials manufactured within 500 miles of the job site may be specified, saving fossil fuels and transportation costs.

Use Masonry for ALL Its Worth and apply for an Innovation in Design LEED point. Four innovation points are allowed per project for greatly exceeding LEED requirements.

They say, “the only constant in life is change.” Maybe they should add taxes. The masonry industry is at the fledgling beginnings of one of those changes. This paradigm shift is driven by the high price of steel and oil. I believe, at present, the Arabs and the Chinese may be the masonry industry’s best friends. Their great demand for steel is driving prices up and cause for extending lead times.

Ed Davenport is CEO of Davenport Masonry, Inc, mason contractor specializing in new construction, restoration, preservation and building maintenance headquartered in Holt. Davenport is a trustee on the MIM board, Mason Contractors’ Association (MCA) board, Michigan Mason Contractors Association (MMCA) board, president of Michigan Council of Employers (MCE) and regional vice president of Mason Contractors Association of America (MCAA). He has worked over 35 years in the construction industry, beginning as a laborer at the age of 17. He was recognized as Masonry Construction Magazine’s 2006 Industry Leader of the Year. Davenport Masonry was founded in 1993 with strong business practices, emphasis on training, safety and innovation. He encourages every employee to think and keep his/her mind open to new ideas, technology and processes. This email address is being protected from spambots. You need JavaScript enabled to view it., 517-699-6153

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Written by Martha Quillin on . Posted in Industry Articles.

After Raleigh Apartment Fire, Safety of Wood Construction Questioned

As flames chewed through hundreds of thousands of board feet of exposed lumber and plywood in a spectacular fire at an under-construction apartment building in downtown Raleigh Thursday night, a question swirled like smoke. Why build an apartment out of wood?

It may seem counter intuitive to see a full-scale return in 2017 to the same building materials colonists hewed from the forests when they first landed in the New World. But all over Raleigh, and especially downtown, along Hillsborough Street and around Cameron Village, wood-frame apartment buildings have proliferated in the post-recession housing-market rebirth because they’re an economical way to build highly demanded high-density housing.

“There is a trend around the country to build these types of buildings all over the place,” said Barry Gupton, secretary to the N.C. Building Code Council, the 17-member board that oversees the state’s voluminous building regulations. “They’re all over Raleigh, Charlotte, Greensboro, and other parts of the country too.”

The Metropolitan, which burned as people watched from nearby streets and over internet feeds, was one of the most common types of modern wood-frame buildings. Known as a pedestal or podium building, it’s actually two structures: a poured-concrete first level – the pedestal – with four stories of wood-frame construction on top. Another popular form is wood framing directly on a concrete slab.

A change in the national building code in 2009, adopted by North Carolina, increased the number of wood-frame stories that can be built on a pedestal or slab from four to five.

International, national and state building codes allow this type of structure and The Metropolitan passed more than four dozen city inspections, including one just a few days before the fire. Those who build them say these mid-rise light wood buildings are economical to build because of savings in labor and materials compared with concrete and steel; that they are more “green” because wood is a renewable resource; and, once the frame is enclosed in fire-resistant materials and sprinkler systems are installed, the buildings are as safe as any other type of structure.

Firefighting groups, however, have expressed concern over the growth of multi-family wood structures, saying that when a fire does occur, it can spread quickly in the right conditions and create special hazards for firefighters. Proponents of competing building materials, such as masonry, say builders who use wood for mid-rise buildings emphasize cost savings over durability and safety.

One thing they all agree on is that whatever sparked the Metropolitan fire sometime before 10 p.m. Thursday, it came at a most opportune time.

“The most vulnerable time in the life span of any building is when it’s under construction,” said Steve Schuster, a Raleigh architect with nearly 40 years’ experience. Schuster mostly repurposes older buildings, but does new construction and has built some wood frame buildings smaller than The Metropolitan. That building’s designer is JDavis Architects of Raleigh. Construction firm Clancy & Theys in Raleigh is building it.

“Anything that is partially done doesn’t have all the components that a finished structure is going to have,” Schuster said. “The very things that make a building like this safe when it’s completed weren’t there yet.”

NO MATERIAL FAIL-SAFE

The five-story, 241-unit, $51 million Metropolitan on North Harrington Street is a project of Banner Development, a Chicago-based company whose specialties are multi-family and senior-living developments, and self-storage structures. The company plans to rebuild on the site as soon as it is able, said Banner’s president, William Henry.

 

“Everything was in place,” he said. “It was just bad luck.” He estimated Friday evening that the building, which was scheduled to open this fall, was 40 percent complete.

“Whatever happened, whether it was set or it was an accident, it was exactly at the right time to maximize damage,” said Jim Anthony, CEO of Collier’s International in Raleigh, another developer of multi-family housing that uses wood-frame construction.

Whether it’s in Raleigh, Charlotte or Los Angeles, a building like this would go up in similar fashion, starting with a concrete slab. If the building includes a pedestal, which might house a parking structure or ground-floor retail or other commercial use, that’s built next, with reinforced concrete walls and top. Concrete or block is used also for stairwells and elevator shafts. One by one, the wood-frame stories go up next, most often with concrete between floors to increase fire resistance, add stability and insulate sound between units. Once the frame is up, the outside walls and roof are added to close the building off to the elements. Plumbing, heating, cooling, electrical systems and sprinklers are roughed in. Flooring is installed, along with drywall, which covers the wood and protects it from fire. As the building nears completion, heads are installed on the sprinkler system that melt when exposed to heat, releasing water directly where a fire is detected to suppress flames and give residents time to get out.

Kirk Grundahl, an engineer and executive director of the Structural Building Components Association, a trade group that represents the producers of wood framing elements, said that once completed, wood-frame buildings are no more fire-prone than structures with steel or concrete frames.

“It’s not about the wood frame,” Grundahl said. “Wood frame has been used in constructing buildings very well for society for over 200 years.”

No construction material is fail-safe in a fire, Grundahl said; at high temperatures, concrete explodes, steel buckles and glass shatters.

“It’s not the building’s fault. It not the wood’s fault,” Grundahl said. “The wood didn’t spontaneously combust. Something started the fire, and it happened at the building’s most vulnerable stage. It’s like when a baby is born, and it has no protective mechanism at all. If somebody drops the baby, what happens? It’s the same deal here.”

Lt. Shawn Burns, who has spent 21 years in the Raleigh Fire Department and is president of the fire union, agreed that wood-frame buildings are safe once finished and have sprinklers installed. State law has required sprinklers in apartments since 2006.

“The problem is when they’re going up, they’re a four-story lumber yard,” he said.

Fire Engineering, which publishes a magazine for fire service workers, has articles on its website explaining the construction of mid-rise wood-frame buildings and describing hazards it says firefighters should be aware of. In a video on the site, a New Jersey fire marshal points out avenues where fire can travel horizontally or vertically, and cautions that when a wood-frame building is engulfed, firefighters should not get over or under wood trusses.

Notable fires in modern wood-frame buildings include two in New Jersey; one in 2000 at an apartment building that was under construction and another in 2016 in a building that was finished and occupied. New Jersey is considering toughening its building codes.

A wood-frame townhome building in Raleigh caught fire in 2007 after someone tossed a cigarette onto landscaping materials. The ensuing blaze leveled more than 20 units when it traveled through the building’s soffits, and resulted in changes in the building code regarding soffit construction and landscaping materials.

A COST-EFFECTIVE ALTERNATIVE

Builders say it’s difficult to compare the costs of wood-frame construction for apartment buildings to steel or concrete because of all the variables, including building type and size and where it’s built. One trade publication says that in certain applications, up-front costs using wood can be as much as 40 percent less than with other materials. Savings come in the cost of raw materials, the speed of construction and the availability of workers trained to handle different materials. In a setting where land costs are high, developers may find a mid-rise wood-frame building an affordable way to get higher density at lower cost.

Jeff Buczkiewicz (pronounced “BUCK-uh-witz”) president and CEO of the Mason Contractors Association of America, which promotes the use of brick, block, tile, terra cotta and stone, argues that while up-front costs may be lower on a wood-frame building, masonry is more durable.

“There is economical concrete block and alternative materials that are used in low-income housing that are very competitive with wood,” Buczkiewicz said. “And in 30 years, they’re going to be in a whole lot better shape.”

Looking at photos from the fire, Buczkiewicz couldn’t help pointing out, “You see what’s still standing. It’s the block walls for the stairwells.”

The photos also show significant damage from The Metropolitan fire to its neighbor, the Link Apartments. That, too, is a multi-story wood frame building. It opened last year and is about 94 percent occupied, said Emily Ethridge, spokewoman for Grubb Properties, its developer.

The Link building did not catch fire but has heat and smoke damage on the side that faced the conflagration, and interior water damage from fire hoses and sprinklers.

Ethridge said what happened at the Link is a testament to the integrity of a wood-frame apartment building.

“The fire alarms went off, the sprinklers went off, everyone did what they were supposed to and evacuated the building,” Ethridge said. “Everything worked the way it was supposed to.”


To view the originally published article, click here.

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