In a recent construction litigation case, there was a disagreement between two qualified engineering experts regarding the technical requirements of a masonry veneer cladding system that was installed on the exterior walls of a residential structure. The disagreement among the experts was related to the classification and function of the veneer cladding system. Specifically, the classification of the cladding system as cast stone or adhered masonry veneer directly impacted the functional requirements set forth by applicable codes and standards. Depending on this classification, the veneer system may or may not be subject to various aspects of the building code, industry standards, and code evaluation reports. The primary areas of concern included the attachment of the panels (i.e., anchored vs. adhered) to the masonry substrate, the extent of water intrusion, and the need for water management details (i.e., flashing and weep holes). Both expert witnesses relied on applicable building codes, industry standards, and manufacturer literature to form their opinions to a “reasonable degree of engineering certainty,” yet these technical differences remained. This paper presents the technical highlights of this case study and identifies the issues where building codes and applicable standards require further clarification.
Many existing unreinforced masonry (URM) structures around the world are vulnerable to failure due to out-of-plane and in-plane loading from extreme wind or earthquakes. Due to several failures of masonry structures during earthquake events (e.g. Newcastle, Australia in 1989 and Kocaeli, Turkey in 1999) the development of new techniques for strengthening or repairing masonry structures is in high demand.
Brick construction has been around for a very long time. Bricks of various forms have been used in construction for thousands of years. Early brick construction consisted of solid, load-bearing walls.
Unreinforced masonry (URM) structures comprise a considerable proportion of the building stock worldwide. However, these structures generally do not behave well under extreme wind or earthquake loading. As part of on-going research, methods of repairing or strengthening URM walls subject to out of plane loading using fiber-reinforced polymers (FRP) are being investigated. For several reasons, one method showing particular promise is the use of near-surface mounted (NSM) Carbon FRP strips.
The Exterior Insulation and Finish System (EIFS) was originally developed in West Germany in the 1960s. The original market for EIFS was introduced in the U.S. in the 1970s. U.S. manufacturers adapted EIFS for use on new construction, including wood-framed structures.
The controversy over Exterior Insulation and Finish System (EIFS) is nothing new. Over the past several years, the construction industry (as well as attorneys, homeowners, architects, engineers and anyone else who has been paying attention) has recognized the importance of waterproofing details.
I was recently given the opportunity to design a new roof for a resort property in Grand Cayman, British West Indies. My experience was pleasant, and the client is happy with the finished roof.
This article identifies design and construction practices that limit or prevent free drainage. Potential solutions are presented to mitigate ponding that contributes to serviceability issues and structural framing damage. The goal is to raise awareness in the construction industry of typical practices that may cause harm to structural members and the building enclosure.
Chapter 15 in the 2015/2018 International Building Code (IBC) contains installation guidelines that permit a design slope of 1/4 in 12 for certain types of roof covers. Specifically, the code text typically reads, “...roofs shall have a design slope of not less than one-fourth unit vertical in 12 units horizontal (2% slope) for drainage.” The stated and intended purpose of the code-specified 1/4 in 12 slope is to provide drainage; however, ponding water is often observed in these low-slope roofs. The standing water is a primary source of roof cover discoloration and deterioration that may result in framing member damage and contribute to premature failure of the structural system. Additionally, building code deflection ratios fail to consider the short- term deflection that exacerbates the potential for ponding water. Therefore, the 1/4 in 12 code-permitted slope requires further investigation by the building design professional. The focus of this article is wood framing members; however, the principles presented are applicable to framing members of any material.
Metal roofs continue to gain popularity in both residential and commercial applications. Metal roofs can provide yeam of performance with minimal maintenance required. However, as with all roof assemblies, the overall performance is dimtly related to the attention to details during installation
With so many finish options available for metal roof panels, choosing the right one can be difficult. This article is intended to guide the reader through the selection process by providing basic information on the most popular finishes.
Conventional build-up roof (BUR) assemblies have lost market share in recent decades to other roofing options. While BUR can provide years of dependable service at a competitive price, concerns of the use of hot asphalt have been expressed by building owners
Can your roof withstand a wind of 110 miles per hour? How do you know? Most building owners do not know the wind speed that their roof assembly can withstand without failure. Building codes set forth minimum construction standards which include a design wind speed. Roofing manufacturers make claims regarding their products' ability to resist specific wind speeds.
Construction Science & Engineering, Inc. an architectural and engineering firm, has investigated several low slope roof applications with water stains, ponding, framing damage on the lower side of the roof span, and structural collapse. Further examination typically reveals a relative level surface when compared to other roof locations (Figure 1). A similar occurrence is often found in exterior deck applications (Figure 2). In studying this potentially problematic issue, two-building code parameters were identified that contribute to low slope roof and deck serviceability issues. This article examines susceptible bays with respect to the 1/4 in 12 design slope and code permitted deflection ratios. Part 2 will identify design and construction practices that contribute to serviceability issues.
The degradation of strength properties related to the presence of fire retardant treatment (FRT) in wood has been previously documented. The degradation process is directly associated with environmental conditions
ANSI/TPI 1-2014 requires building designers to identify in construction documents any conditions that are expected to result in high wood moisture content, sustained high temperatures or environments that have the potential to cause truss plate corrosion. Each condition requires a reduction in lumber or connector plate design values. In addition, the environment may require chemical treatment of the lumber or corrosion protection plates. Truss technicians who recognize the situations that create these conditions can implement appropriate design practices to mitigate potential serviceability issues and to ensure the trusses are designed to perform as intended by the building designer.
The author’s company, a forensic engineering and architect firm, has investigated hundreds of low-slope roof and exterior deck applications with water stains, ponding, framing damage, and structural collapse. The first article, Part 1: 1/4 in 12 Design Slope and Water Drainage (page 11), examined two building code parameters that contribute to low-slope roof and deck serviceability issues. This article identifies design and construction practices that limit or prevent free drainage. Potential solutions are presented to mitigate ponding that contributes to serviceability issues and structural framing damage. The goal is to raise awareness in the construction industry of typical practices that may cause harm to structural members and the building enclosure.
Over the past several years, the author has observed an increasing number of water intrusion claims in relatively new mid-rise wood-frame buildings. While the code requires the building envelope to provide protection from the weather, it does not provide the details necessary for designers and/or contractors to meet this requirement. More specifically, vertical and lateral movements, caused by frame compression, shrinkage, external loads and material incompatibility, can compromise the function of flashing, drainage and waterproofing details. Differential movements between the wood framing and exterior cladding components can cause physical damages to building enclosure components that increases the extent of water intrusion. Once the water reaches the wood framing components, significant damages such as decay, corrosion and mold can result. Additionally, once compromised, the effectiveness of products used to meet fire resistance requirements is unknown.
Recent changes in the building code helped fuel the current surge in mid-rise wood frame construction projects. Over the past several years, there has been an increasing number of water intrusion claims in relatively new mid-rise wood-frame buildings. While the code requires the building envelope to provide protection from the weather, it does not provide the details necessary for designers and/or contractors to meet this requirement. Typical construction details, that have had limited success on 1 to 3 story wood frame buildings, are even more problematic on taller buildings. Specifically, vertical and lateral movements, caused by frame compression, shrinkage, external loads and material incompatibility, can compromise the function of flashing and waterproofing details. Differential movements between the wood framing and exterior cladding components can cause physical damages to building enclosure components that increase the extent of water intrusion. Once the water reaches the wood framing components, significant damages such as rot, corrosion, and mold can result. Additionally, once compromised, the effectiveness of products used to meet fire resistance requirements is unknown. If our design and construction of the building enclosure do not incorporate “best practices”, mid-rise wood frame buildings may become the “black eye” of the construction industry.
The degradation of wood strength related to the presence of fire retardant treatment (FRT) has been previously documented. The degradation process referred to as "acid-catalyzed dehydration," is directly associated with environmental conditions such as temperature and humidity.
Toe-nailing is often used to attach corner and end jack trusses to the corner and hip girder trusses, respectively. The relatively short spans and light end reactions associated with most jack trusses make toe-nailing an efficient and effective attachment method. The International Building Code (IBC), International Residential Code (IRC), and ANSI/TPI 1-2002 require that truss-to-truss girder connection information be included on the truss design drawing. Because of this, it is not uncommon for building code officials and building designers to request "certification" of this connection. The challenge is to address these connections in a timely manner and to know what documentation is available or can be provided.
An engineer's perspective on a previously written column about second-story wall girders.
A primary focus of truss design is ensuring each truss component has sufficient capacity or strength to safely support design loads. The serviceability issues rarely affect life-safety and are sometimes marginalized by strength design. However, the vast majority of truss complaints received by component manufacturers relate to serviceability performance. An awareness of the typical serviceability issues that can adversely affect truss performance is crucial. Many potential complaints and problems can be mitigated by an astute truss technician during the design phase.
It doesn't take long in this industry to discover that designing trusses to meet code-permitted deflection ratios does not guarantee satisfactory performance. This article addresses the movement of adjacent trusses in a floor or roof system, as measured against each other, also known as relative or differential deflection.
The purpose of this article series is to identify truss-related structural issues sometimes missed due to the day-in and day-out demands of truss design/production and the fragmented building design review and approval process. This series will explore issues in the building market that are not normally focused upon, and provide recommended best-practice guidance. The objective is to raise awareness of these issues and, ultimately, improve the overall quality of truss roof and floor system construction.
The first two articles discussed deferred submittals and truss-to-truss connections. This article explores truss minimum required bearing width issues from the perspective of the design community. The purpose of this series is to identify truss-related structural issues sometimes missed due to the day-in and day-out demands of truss design/production and the fragmented building design review and approval process. This series explores issues in the building market that are not normally focused upon, and provide recommended best-practice guidance. As with the previous articles, the objective is to raise awareness of these issues and, ultimately, improve the overall quality of truss roof and floor system construction.
The truss industry standard of care items is contained throughout ANSI/TPI 1, The National Standard for Metal Plate Connected Wood Truss Construction. The focus of this article is ANSI/TPI 1 Chapter 2, Section 220.127.116.11 and companion Section 18.104.22.168, which requires a truss designer to prepare truss design drawings (TDD) based on design criteria and requirements set forth in the construction documents. The purpose of this series is to identify truss-related structural issues sometimes missed due to the day-in and day-out demands of truss design/production and the fragmented building design review and approval process. This series explores issues in the building market that are not normally focused upon, and provide recommended best-practice guidance. As with the previous articles, the objective is to raise awareness of these issues and, ultimately, improve the overall quality of truss roof and floor system construction.
Production builders and developers began to encourage building material supply (BMS) companies to deliver a "dried-in" framing package in the late 1990s. This presented an opportunity for a BMS to sell manufactured and/or inventoried products and the labor to install them. Many BMSs began to offer "installed sales" as an avenue to capture large-volume customers and increase company revenue. Additionally, many BMSs have a truss and/or wall panel division or resell truss and wall components that become part of the installed-sale framing package. It is judicious for BMSs that coordinate building framing and install building components to be knowledgeable of applicable code sections, industry standards, and manufacturer instructions. The purpose of this series is to identify truss-related structural issues sometimes missed due to the day-in and day-out demands of truss design/production and the fragmented building design review and approval process. This series explores issues in the building market that are not normally focused upon, and provide recommended best-practice guidance. As with the previous articles, the objective is to raise awareness of these issues and, ultimately, improve the overall quality of truss roof and floor system construction.
While mid-rise wood frame construction has its own set of unique challenges, the student housing version of this relatively new product represents the "perfect storm" where the risk of performance issues is drastically increased. This opinion is based on the extent of problems that the author has investigated over the past few years, as well as personal knowledge and observation of multiple student housing projects during construction. The frequency of student housing cases (e.g. structural failure, water damage, etc.) seems to be increasing, as more of these buildings spend time in service and begin to show signs of distress. The author felt strongly enough about this issue to send a letter to two prominent national newspapers in early 2018.
As licensed design professionals, we have a legal duty to design and construct buildings to meet minimum building code requirements. This article, however, attempts to highlight positions taken in the context of litigation where minor technical deviations from the code (which have little to no consequences on the overall performance and/or safety of the building) are used to minimize or expand repair scopes in order to influence the "value" of the case.
No matter how tough times get, the business of construction litigation seems to go full steam ahead. Each claim typically has at least one real problem that serves as the mode of discovery for the building owner. However, when this problem is investigated, the investigator (typically a professional engineer or licensed architect) is asked to provide a list of any other issues that may represent deviations from the project plans and specifications, applicable building codes, accepted industry standards, or manufacturer instructions (collectively referred to as contractor's instructions).1 After all, the plaintiff only gets one opportunity to provide a list of alleged defects to which the defendants will respond. This scenario often causes unsuspecting building owners (who may have thought they only had a leaky patio door-the one real problem that initiated the process) to face a myriad of alleged defects that essentially require the building to be reconstructed from the framing out. It has become common for plaintiff reports and their associated repair scopes to require complete removal and replacement of roof coverings, the exterior cladding (e.g., brick veneer, siding, stucco, etc.), windows, doors, balcony waterproofing systems; and even the reconstruction of concrete driveways, patios, and sidewalks. Could the construction of new buildings really be that bad? With so much "wrong" with these buildings, it is surprising that they ever passed inspection or were sold to discriminating buyers and represented as quality construction. The fact is (and anyone who provides an honest evaluation of constructed buildings should agree), many of the alleged defects simply represent deviations from the contractor's instructions. Some deviations actually have a consequence such that a repair is warranted, while many do not. This paper will discuss the first element of a typical construction litigation case, the identification of defects, and will provide commentary based on direct involvement in numerous cases in which the authors have provided expert services to both plaintiffs and defendants. Parts II, III, and IV (to be published in subsequent issues of HBEC Interface) will discuss the expert report, repair scope, and testimony aspects of construction litigation, respectively.
Based on recent experience in construction litigation, it appears that much confusion exists regarding written instructions used by contractors during the course of a project.
There are six sides to a building that engineers, architects, and consultants must consider during the design phase of a project. A key element is the design and installation of the exterior wall cladding on four of those six sides. Over the years, the construction industry has been introduced to several types of exterior cladding. Cementitious horizontal lap siding (also known as fiber cement board siding) is one of the most popular choices for higher-end single-family and multifamily wood-framed residential buildings. There has been an increase in the installation of fiber cement board siding in coastal environments, where wind pressures are typically higher. Criticisms of the installation of the fiber cement siding attachment have become common in the context of construction litigation, with some expert witnesses opining that complete removal and replacement of the siding is required when not installed in accordance with manufacturers' installation instructions. In addition to relying on the applicable building codes, accepted industry standards, and manufacturer literature, expert witnesses should utilize engineering judgment and experience to formulate opinions. Expert witnesses should evaluate, analyze and suggest reasonable repairs based on the as-built attachment conditions of the fiber cement board siding for each case, and avoid generalizations that replacement is required if manufacturers' installation instructions are not followed exactly. Over the past several years, leading industry groups and manufacturers have provided supplemental information that has allowed expert witnesses to further analyze and formulate reasonable repairs that may not require removal and replacement of the siding system. This article is intended to provide a basic understanding of siding attachment issues that are frequently discussed during construction litigation cases involving fiber cement board siding.
If you are a building envelope consultant or are familiar with exterior wall design, you have likely heard of the Four Ds of exterior wall design, Each "D" stands for an important feature of the design that is needed to reduce problems with elevated moisture and to improve durability. When one or more of the Ds are not provided, failure of the exterior wall assembly can result. Failure could range from corroded fasteners and stained wall sheathing to rotten framing and structural collapse, with many variations between. Based on many years of forensic experience, it has been observed that in every wall failure, not only is one of the Four Ds of wall design not accomplished, but an opposite and harmful "D" may exist in its place. Specifically, for every one of the Four Ds of good wall design, there exists an opposing "D" that can cause or contribute to wall failure.
Depending on installation details, exterior trim can be a critical element of the building envelope, particularly on single- and multi-family residential construction.