Iano's backfill

State of the Art Glass Engineering

As Unbreakable as ... Glass? (www.nytimes.com, July 6, 2009) discusses developments in the manufacture and use of glass as a structural material.

Interesting supplemental material accompanying the article includes a video and graphic illustrations of the glass booths' construction, a slide show of noteworthy applications of structural glass in architecture, and a graphic explanation of the processes for thermal and chemical tempering of glass.

A link to a video clip on youtube.com, illustrating Prince Rupert's Drop, a simple and intriguing demonstration of heat strengthening of glass in action is also worth a look.

New Wood Preservative Treatments

Pressure-Treated Wood: The Next Generation (Journal of Light Construction, April 2009) reports on new chemical preservative treatments for wood that promise to be less corrosive than the current generation of preservatives, but that leave unanswered questions about long-term performance.

Second-Generation Preservatives
Until recently, the two most popular chemicals used to treat wood for protection from decay and insect attack were CA (copper azole) and ACQ (ammoniacal copper quaternary or alkaline copper quarternay). Both of these chemicals rely on high concentrations of dissolved copper for their resistance to attacks by fungi and and insects. But these high copper concentrations, can also cause rapid corrosion of metal fasteners and framing hardware with which the treated wood comes in contact.

For example, the article refers to tests of ACQ treated lumber with plain or galvanized steel which have shown corrosion rates 5 to 15 times that of CCA, the preservative chemical that ACQ and CA replaced but that was removed from the market in 2004 because of concerns for health hazards due to its arsenic content.

Third-Generation and Beyond Preservatives
Unlike CA and ACQ, in which the copper is in a dissolved (ionized) state and relatively free to migrate, a new family of chemicals rely on finely ground particles of copper in suspension that results in less free copper ions and less corrosion of metals. Chemical formulas, which vary with preservative manufacturer,  include uCA-C (dispersed copper azole), MCA (micronized copper azole), and MCQ (micronized copper quaternary). Manufacturers of these copper-suspension treatment chemicals claim reduced corrosion rates in comparison to copper-solution treatments. 

Preservatives which rely on boron for decay prevention are another alternative. These chemicals have no corrosive affect and no know health risks. But most are also highly water soluble, making them suitable only for applications protected from the weather such as interior wood framing for structures in areas of high termite risk. One treatment manufacturer produces a borate treatment chemically bound to the wood such that it can be used for exterior, non-ground contact applications.

The newest family of preservatives entering the market are based on organic insecticides and fungicides with no copper or other metals. These so-called "carbon-based" treatments promise much lower corrosivity than copper-based treatments. Currently available products are suitable for above-ground use only and include the chemicals EL2 (DCOI-Imidicloprid) and PTI (Propiconazole-Tebuconazole-Imidicloprid).

Performance
While new treatment chemicals must pass laboratory testing to demonstrate their effectiveness, their true long-term performance in real-world conditions won't be certain for decades. In the mean time, designers and builders must base their product selections on the results of standard testing and manufacturer certifications.

More Info
http://www.archchemicals.com/Fed/WOLW/
www.treatedwood.com
www.osmosewood.com
www.frtw.com
www.phibrowood.com

Bridge In A Backback

Maine first to use process for stronger bridges (forbes.com, 4/11/2009) describes innovative concrete bridge-forming technology developed at the University of Maine's Advanced Structures and Composites Center.

Formwork for concrete arches is made from lightweight, composite fabric tubular arches that are prefabricated off-site and then folded up for easy transport. Once on site, the arches are inflated into final shape and then filled with concrete. The fabric tubes, made of a carbon-glass fiber blend coated with resin, become an intergral part of the concrete  structure in the finished construction. Erection of formwork and pouring of the concrete arches can all be accomplished in as little as one day's time.

The Center's own web site provides information on a range of technologies in development, such as composite-reinforced structural wood panels, glulams, and more.

Mortar for Masonry part 1: Cement

Cement-lime mortar used for brick and stone masonry is made up of cement, aggregate, lime and water. Aggregate forms the structural body of the mortar, cement is the glue that binds the aggregate, lime improves the workability of the uncured mortar, and water chemically combines with the cement to cause the mortar to harden as well as contributes to the plastic consistency of the wet mortar.

PORTLAND CEMENT
Portland cement, the most common cementitious material in mortar consists primarily of calcium silicates. Common sources of calcium include limestone, marble, and other minerals, and of silica, clay, sand, shale, and marl. Lesser quantities of compounds of iron, aluminum, magnesium, and sulfur are added to improve the hydration properties of the finished cement (hydration is explained below).

The raw materials are ground to a small particle size, blended, chemically combined in a large, high-temperature kiln, finely ground again, and mixed with a controlled amount of gypsum to produce portland cement. In its finished state, the cement particles are very small, ranging in size from 0.0004 to 0.0006 inches in diameter.

Portland cement is an hydraulic cement: It hardens by chemically combining with water, a process called hydration. The small size of the cement particles is important to ensuring the fullest possible hydration of the cement during the curing process.

OTHER CEMENT TYPES
Blended hydraulic cement is a mixture of portland cement with other cementitious materials such as blast furnace slag (itself an hydraulic cement), or any of a number of pozzolans (materials that react with the calcium hydroxide in wet portland cement to form other cementing compounds) such as fly ash, silica fume, or natural pozzolans derived from shales or clays.

The use of blended hydraulic cements reduces the quantity of portland cement in the mortar, reducing the energy required to manufacture the cement. Depending on their formulation, blended hydraulic cements can produce mortars with increased strength, lesser permeability, and other favorable properties in comparison to portland cement-lime mortars.

Masonry cements and mortar cements are proprietary blends of various cementitious materials, lime, and other ingredients. Unlike mortar made from portland cement or blended hydraulic cement (cement-lime mortars), mortar made from either masonry cement or mortar cement does not need the addition of lime as a separate ingredient. Both of these cement types offer the convenience and consistent quality of factory mixing, and can produce mortars with improved workability when wet, less shrinkage while drying, and other benefits. Masonry cements, which rely, in part, on air entraining (the generation of very small air bubbles within the mortar mix) for their workability, have a lower bond strength than cement-lime mortars, and may not be suitable for some applications, such as masonry subject to high wind or seismic forces. Mortar cements are produced to a different standard that produces mortars with bond strength comparable to cement-lime mortars.

Lime mortar is made with just lime, aggregate, and water--in this type of mortar, lime itself acts as the aggregate binder. In the absence of any hydraulic ingredients, lime mortar cures as atmospheric carbon dioxide gradually combines chemically with the mortar, a process called carbonation. Lime mortars are primarily used in the restoration of historic masonry where it is important that new materials used to repair such structures have physical properties close to those of the the original materials. Lime mortars with varying degrees of hydraulic properties and greater compressive strength can also be produced by adding varying amounts of other cementitious materials to the mortar mix.

	Hydraulic cement	Lime and other workability agents	Aggregate
Portland cement-lime mortar	portland cement	lime	sand
Mortar with blended hydraulic cement	blended hydraulic cement	lime	sand
Mortar with masonry cement	masonry cement		sand
Mortar with mortar cement	mortar cement		sand
Lime mortar	(none)	lime	sand

Animated Constructions

  Theo Jansen's web site documents his fascinating animated constructions that seem to fall somewhere at the intersection of construction, art, and biology. To fully appreciate the concepts involved, including the programmed survival instincts of the constructions, see the TEDTalks clip on the film page.

What's In a Green Highrise?

 MetroTower III aims to reach new heights for green building (Journal of Commerce, December 4, 2008) describes this 25-story tower, USGBC's first Canadian pre-certified LEED Platinum core and shell commercial building structure.

Attaining LEED certification will purportedly add $1.5 million to the $170 million project and is expected to reduce annual operating costs by $75,000.

Among the building's green attributes are:

• Large windows, light sensors, heat exchangers, and reliance on renewable energy sources, contributing to energy conservation
• A curved southwest facade to maximize daylight in a nearby outdoor plaza
• Low-e glass that admits more daylight, but less heat
• Collection of rainwater for landscape irrigation and flushing of toilets
• Drought-resistant landscaping and restoration of native habitat
• Replacement of trees removed for construction
• Access to public transportation
• Regional materials and materials with recycled content
• Recycling of construction waste
• Certified woods for finish carpentry
• Shower and lock-up facilities for bicycle commuters

The developers claim a 35% reduction in the building's carbon footprint.

Fundamentals of Building Construction, 5th Edition

Authors Edward Allen and Joseph Iano are pleased to announce the release of Fundamentals of Building Construction, Materials and Methods, Fifth Edition.

Thoroughly revised, this new edition of Fundamentals provides the most up-to-date survey available from any source of the materials and methods used in modern building construction. Using the latest building codes, standards, and developments in materials and technologies as its basis, this book covers the complete range of construction activities—from excavating and foundations to cladding and interior finishes—and examines common construction systems such as light wood frame, masonry, steel, and reinforced concrete.

The Fifth Edition adds a host of updated and completely new information on such current topics as:

• The role of the construction contractor in the process of making buildings
• Construction management and methods of project delivery
• Controlling the movement of heat, air and moisture through the building enclosure
• Pre-engineered building components
• Sustainability and green building techniques
• Innovations in glass, concrete, wood and other construction materials
• The 2006 International Building and Residential Codes, 2004 MasterFormat, and the latest ASTM references, and LEED standards

Supplemented by Exercises in Building Construction 5E, available separately, Fundamentals of Building Construction, Fifth Edition lays the foundation every architect and builder needs to build a successful career.

Codes, Standards, & Specs

What are the differences between Codes, Standards, and Specifications, and how are they related?, from the Portland Cement Association's Concrete Technology FAQ, is a succinct description of how these three types of information interrelate. In short:

Codes:

Codes are legal requirements for building that are enforced by the local jurisdiction, such as city, county, or state. In the U.S., most building codes are based on the model codes published by the International Code Council, a private, not for profit, codes and standards development organization.

Standards

Standards are voluntary recommendations for good building practice that are usually developed and published by organizations with an interest in the construction industry. For example, AAMA/WDMA/CSA 101/I.S.2/A440-08, NAFS, North American Standard/Specification for windows, doors and skylights is a performance standard developed by a group of window and door industry trade associations. On its own, this particular standard is voluntary. But since it has become adopted by reference into the model building codes, its requirements have also become legally mandatory.

Specifications

Specifications are written documents that detail quality of materials and methods of construction. Specifications may be written by the design team and become enforceable as part of the construction documents for a construction project. Or, like standards, they may be written by any number of private parties and remain either voluntary, or, if adopted into the codes, become legally mandated.

ASTM Standards
ASTM is one of the leading publisher of construction standards. The executive summary of any ASTM standard can be found on the ASTM web site. From the home page, click on the Standards Search link--don't click on the Site Search link. Next, in the Search Standards box, enter the standard designation, such as "C150" and click Search. The first result listed is typically the current standard. Full copies of the standards are also available for purchase either in hardcopy or digital format.

Specifications Numbering
Most construction specifications are organized with a numbering system called MasterForamt, published by the Construction Specifications Institiute. For more information on this system, Need help with Masterformat specification numbering? From the Construction Specification Institute home page, follow links to Standards and Formats and look for links to MasterForma Numbers & Titles. The complete MasterFormat documentation is also available (for a fee) at www.masterformat.com.

Complexities of Sustainability

LEED as the Definition of Sustainability
Can LEED Survive the Carbon-Neutral Era (Metropolis, November 2007) discusses the growing acceptance of the US Green Building Council LEED rating system while also considering future challenges to its relevance:

• USGBC claims 40,000 LEED-accredited professionals. The organization has certified only roughly 1000 buildings since its inception.
• A recent study by construction consultant Davis Langdon claims that LEED-certified buildings, at least up to the Gold certification level, need not cost more than conventionally designed buildings. Fiona Cousins of ARUP New York estimates it can cost $100,000 in service fees to document building performance for LEED.
• Until June of this year, buildings could achieve LEED certification without receiving any energy performance points associated with reductions in carbon emissions.
• ASHRAE, in conjunction with USGBC and others, is promoting its Advanced Energy Design Guides which target energy savings of 30% over current national  standards. ASHRAE intends to introduce similar mandatory standards by the year 2012. ASHRAE and the AIA are proposing national legislation that would require new buildings to be fully climate-neutral by the year 2020.

The article also discusses the pros and cons of the LEED "checklist" methodology for defining sustainability, in contrast to more ntegrated approaches to sustainable building design. And the article speculates on the possibility of LEED's broad definition of sustainability, which includes considerations of site and community development, materials and resources, and indoor air quality, being preempted in the future by the need to focus more narrowly on the conservation of water and energy.

Separately, The Battle for Green Building (Springfield Business Journal, 12/11/20067) discusses the Green Building Initiative's Green Globes sustainable building certification program, an alternative to the better know LEED. Though there are many similarities between these two programs, Green Globes is reportedly distinguished by its pending certification by the American National Standards Institute, and its lower implementation cost than LEED.

PVC as a Sustainable Material
The USGBC's February 2007 Assessment of the Technical Basis for a PVC-Related Materials Credit for LEED is the that organization's final report on the contentious issue of the use of PVC materials in building construction.

USGBC has been considering this issue since at least the year 2000. The Assessment looks at four common PVC applications: siding, drain/waste/vent piping, resilient flooring, and window frames. Each is compared with common alternatives, for example in the case of siding, with aluminum, wood, and fiber-cement. Materials are evaluated on a number of bases:

• Conventional life-cycle assessment in which all the resource and pollution inputs and outputs associated with the material-- beginning with its harvesting or extraction and ending with its reuse or disposal at the end of its service life--are considered. Impacts on both human health and the environment are included.
• Extended end-of-life analysis in which potential PVC dioxin emissions from backyard burning and accidental landfill fires are considered. Given the large uncertainties in the data for this scenario, upper, middle, and lower range estimates were evaluated.
• Risk assessments of the adverse human health effects due to exposure to toxic compounds generated throughout the life cycle of the materials.

The conclusion: No single material shows up as the best across all human health and environmental impact categories, nor as the worst.

The assessment's results resist simplistic conclusions. Material rankings vary depending on how environmental and human health impacts are prioritized. In other words, a choice of one material over another may benefit human health while increasing adverse effects for the environment, or vice-versa. Rankings also vary with the product category. Only in the resilient flooring category do PVC products rank consistently higher in both adverse human health and environmental effects than alternative materials (linoleum and cork).

Meanwhile, Schwarzenegger Bans PVC Additive In Toys (Healthy Building Network, October 25, 2007) reports that, despite claims made by the Vinyl Institute regarding the safety of PVC in children's toys, the state of California has passed legislation prohibiting the use of phthalates, a PVC plasticizer, in products intended for babies and children under three years of age. The article goes on to state:

Like the human carcinogens vinyl chloride and dioxin, phthalates are uniquely associated with PVC. It is this triple threat from PVC that distinguishes it as the worst plastic for environmental health and green building. Regrettably, there are still few restrictions on the use of vinyl in green buildings.

Evolving Measures of Material Sustainability
Shedding Light On The Pharos Project (Eco-Structure, December 2007) describes the Pharos Project, an ambitious building products rating program under development by the Healthy Building Network.

The Pharos Project is touted as a database of building materials intended to allow a more comprehensive and sophisticated evaluation of the sustainable attributes of materials than is currently offered by other rating systems. Its unique framework covers a broad range of health, environmental sustainability, and social justice criteria.The Project will also host a Wiki and online forums.

A visit to the Project's web site leaves one questioning whether the Project is alive and well. The most recently dated content appears to be from November of 2006. According to Eco-Structure, the next working version of the Project is scheduled for release in the spring of 2008.

Measures of Sustainable Buildings
Energy Performance Data Largely Lacking (ENR, November 12, 2007) reports that, despite the attention being given to green building design, there is a lack of standards for collecting and analyzing building energy performance data, and, though newer buildings may be designed to be more energy efficient than older buildings, building energy use overall continues to climb:

• According to the U.S. Department of Energy, commercial buildings consumed 18 quads (18 quadrillion BTUs) in 2004, and are projected to consume 25 quads--almost a 40 percent increase--by the year 2030. The largest part of this jump is attributed to increased use of electrical equipment and the increased cooling loads that result.
• Between 1980 and 2000, energy use per square foot in commercial buildings increased by roughly 25 percent.

LEED certification does not necessarily correlate with reduced building energy consumption. On the one hand, Seattle's LEED-Silver Alley24 mixed-used development, completed in 2006, is reportedly close to achieving a 50 percent targeted reduction in CO² emissions. On the other hand, Seattle's new City Hall, also LEED-Silver, completed in 2003, is separately reported as consuming significantly more energy than the larger, older building that it replaced.

Storm-Resistant Home Design

Home Shapes And Roofs That Hold Up Best In Hurricanes (ScienceDaily, Jun. 21, 2007) reports on a research report from New Jersey Institute of Technology identifying design strategies for homes resistant to high winds and storm-driven funding. Among the findings:

• Hipped roofs with a 30-degree slope are the most resistant to wind uplift.
• Homes thats are roughly square in plan are more wind-resistant that those that are more rectangular.
• Roof overhangs should be limited to 20 inches deep.
• An elevated structure is less at risk from storm-driven flooding.

The Delivery of Design and Construction Services

AGC-AIA Dispute Represents Deeper AEC/O Rifts (Cadalyst, Oct 25, 2007) discusses how changes in methods of project delivery, such as building information modeling, are leading to changes in the traditional roles of the designer and builder--changes that do not always come easily.

The upcoming 5th Edition of Fundamentals of Building Construction (due Fall of 2008) will have an expanded discussion of the roles of the building and construction manager in the construction of buildings.

More Info
Building Futures Council
The AGC's BIM Initiatives and the Contractor's Guide to BIM (AEC Bytes)

Roofing Lessons Learned from Hurricane Katrina

Roofing Industry Committee on Weather Issues, Inc's. Hurricane Katrina Wind Investigation Report, prepared in conjunction with Oak Ridge National Laboratory, assesses damage to roofing caused by  Hurricane Katrina in August of 2005. 

One major finding: Peak gust speeds in the inspected areas were estimated at 120 - 130 mph, below the 130 - 150 mph basic design wind speeds required by current codes. As hoped, roofs constructed to current code requirements faired relatively well. Most failures of such roofs were attributable to improper installation or deterioration rather than flaws in the design methodology.

Carbon Neutral Building Design

Green Building Studio Inc. has launched version 3 of their Green Building Studio web-based software for analyzing the energy impacts of alternative building designs. According to GBS, in less than 3 hours you can register your project, submit your BIM building model, review results with your consultants, and tune building parameters to optimize the whole building energy use. The software addresses carbon neutral building, US EPA Energy Star scores, water usage, daylighting, natural ventilation, and other factors.

The BuildCarbonNeutral calculator estimates the C02 emissions of a proposed building based on its size, method of construction, and location. Jointly developed by Mithun Architects and the Lady Bird Johnson Wildflower Center, the tool purportedly:

estimates the embodied energy and subsequent carbon amounts released during construction. The measurements account for building materials, processes and carbon released due to ecosystem degradation or sequestered through landscape installation or restoration.

Accessibility and the IBC

The June 2007 Building Safety Journal is devoted mostly to accessibility regulations and the International Building Code, including discussion of:

• The 2006 IBC and 2003 ICC/ANSI A117.1 accessibility standard have been accepted by the US Department of Housing and Urban Development as a safe harbor for meeting HUD's Fair Housing Act design and construction accessibility guidelines.
• The US Access Board Committee's Courthouse Access Advisory Committee has issued a written report providing guidelines for accessible design in courthouses.
• The US Access Boards ADA and ABA standard continues to move toward adoption by the DOJ. (But the discussion of the application of various Federal agency guidelines leaves this author scratching his head.)
• Accessible design for new stadiums
• Elevators and accessible egress in tall buildings discussed, including ongoing study of elevator-assisted egress
• Theater accessibility
• Accessibility of sinks within work areas
• Differences among adoption of accessibility at the state level

For those dealing with these design issues, this issue of Building Safety Journal is worth a look.

Standards: New (costly?), New (better?), and Needed(?)

ENR's Third Exit Stair Could Make Highrises Too Costly to Build (June 4, 2007) reports on the adoption of more stringent life safety requirements for tall buildings in the 2007 Supplement to the International Building Code. Both the Building Owners and Managers Association International and the American Institute of Architects oppose as too costly a new requirement for buildings taller than 420 feet to have at least 3 independent exit stairs. Other changes to tall building requirements in the 2007 Supplement, all coming in the aftermath of the 9/11 attacks on the World Trade Center Buildings in New York City, include:

• protected fire service elevators and lobbies
• photoluminescent pathway markings in exit stairwells
• inspection and greater strength requirements for spray-applied fireproofing.

Proposals for progressive collapse resistance, increased  exit stairway enclosure integrity, and requirements for a a building's ability to burn without collapse were rejected. See the ICC's Code Development page for more information about that organization's code development process and the adoption of these new requirements.

In the same issue, Energy-Efficiency Guidelines Would Be National Model reports on the American Society of Heating, Refrigerating and Air Conditioning Engineer's (ASHRAE) ongoing development of Standard 89, an enhanced building energy efficiency guideline. Standard 89, now open for comments, is intended to reduce building energy consumption by 30% in comparison to ASHRAE's long-recognized Standard 90, and is being touted as a national standard for achieving LEED certified optimized energy performance. See ASHRAE's Advanced Energy Design Guides page for more about this organization's enhanced energy performance guidelines.

Lastly, Innovative Mix with Fly Ash is Still Not Widely Used describes a concrete mix composed of lime, portland cement, and fly ash developed by Nai C. Yang of the New Port Authority 38 years ago for use in airport runway construction. The mix is claimed to provide superior concrete and a reduction in environmental impact (due to reduction in cement content and, consequently, reductions in C02 emissions). However its broader use in airport construction has been hampered by unfamiliarity and a lack of standards for its production.