This article provides an introductory lesson on building enclosures, including the components of the enclosure, common defects, and how forensic experts investigate these issues.
Building Enclosure Defects
At its most basic, a building is a shelter, an enclosure to separate the indoor environment from the natural elements. This fundamental purpose is compromised when a failure of the enclosure allows transmission of unwanted water, moisture, heat, air, light, or sounds between the indoor and outdoor environments. When a building enclosure failure occurs, an expert is needed to determine:
- Where are the defects which caused the failures?
- What are the causes of the defects?
- Why did these defects occur?
- Who are the responsible parties?
The Building Enclosure The building enclosure, also called the building envelope, is the system composed of the foundation, exterior wall, window, door, roof, and skylight assemblies. Bringing these assemblies together to create a dry, conditioned interior is the most fundamental task in building design. Energy-efficiency has become a driving force in building design and performance expectations for the building enclosure system have increased. Even so, the basic components of each assembly are not complicated:
- The Exterior Finish or Cladding is the visible surface.
- The Drainage Plane keeps the rain out.
- The Air Barrier keeps the wind out.
- The Vapor Control Layer regulates water vapor flow and condensation.
- The Thermal Insulation keeps heat in or out.
- The Structure supports the assembly.
One component may perform more than one of these functions. For example, roofing shingles function as both the exterior finish and the drainage plane for the roof assembly. Common Failures of Building Enclosure Assemblies General indications of enclosure failures include roof and wall damage, water damage, condensation, mold, drafts, “telegraphing” of wall framing members (vertical lines on the interior surface of exterior wall), and higher than expected energy usage. These can usually be traced to defects in the various assemblies or a defect known as thermal bridging:
- The most apparent roofing failure is water infiltration. A leaking roof can damage the building’s contents, finishes, and structure, as well as decrease the insulation value of the roof. Leaks can be caused by design or construction errors, improper maintenance, external damage, or the age of the roofing.
- Ice damming is another defect which can cause damage to the roofing, insulation, interior finishes, and even the structure of a building. Ice dams are masses of ice that build-up at the roof edge, restricting proper drainage and often causing water infiltration. Ice damming is most commonly caused by design or construction errors.
- Design and construction errors in roofing ventilation and water vapor management are additional defects which may result in finish, structure, and insulation damage.
- Cracked masonry walls and warped wooden siding are examples of easily seen wall failures. Behind the exterior finishes, failures of the air barrier, water barrier, or water vapor management systems can result in visible and concealed damage to the wall assembly, drafts, and decreased energy efficiency.
- Compromised acoustical performance can also result from exterior wall defects. Building owners often have requirements for their spaces to be acoustically isolated from environmental sounds such as air traffic, highway traffic, or nearby railroad lines. Should a newly-constructed building not provide the sound isolation for which the owner contracted, design or construction errors are likely to blame.
- Glazing (Windows and Skylights)
- Failed seals between the inner and outer lites of glass in insulated glazing units will cause fogging between the panes and a reduction of insulation value. Failed seals between the glazing and window frame can result in water and air infiltration. Defective window frame drainage systems can result in water infiltration.
- Glazing failures are often the result of manufacturing defects and can be a product liability issue.
- Flashing is an essential component of roof, wall, and glazing assemblies. Properly designed, installed, and maintained flashing directs water away and out: away from openings, material transitions, and material discontinuities, and out of the building envelope. Flashing failures can result in water and air infiltration, often in areas concealed by finish materials.
- Failed joints, such as caulking around windows and movement (control, expansion, construction) joints in walls and roofs, can allow water and air infiltration. Visible and concealed damage, as well as loss of energy efficiency, can result.
- The building enclosure’s primary function is to separate the interior from the exterior environment. Even when water, air, and water vapor transmission are controlled, thermal bridges can severely impact the energy efficiency of the building enclosure.
- A thermal bridge is a direct path through the building envelope through which heat can travel, “short circuiting” elements such as well-insulated walls and energy efficient windows. Thermal bridges can result from defects in individual assemblies, construction errors, or improper design of the building enclosure system as a whole. In addition to energy loss, damage to finishes, insulation, and structural elements may result from thermal bridging.
- Thermal bridges are not easily identified by the layperson.
Building enclosure defects can result in nuisance items requiring regular maintenance, costly defects requiring extensive remediation, or catastrophic failures endangering the building, its occupants, and the general public. It should be mentioned that even “nuisance” items can have a significant economic impact due to increased maintenance and/or energy costs. Why Should Building Enclosure Investigations Be Performed? Building leaks, water damage, wall damage or deterioration, drafts, condensation, and poor energy performance are serious concerns for building owners. When an owner incurs damages from these defects, a building enclosure investigation is needed to determine the responsibility for the damages. The goals of the investigation include: Establishment of the Defects Causing Failures and Performance Issues
- Consider the case of water infiltration in a building at the ceiling below the roof.
- Where did the water come from? Has the damage been caused by a roof leak? Failed sealants? Failed skylight glazing? Condensation? Other component?
- Properly identifying the specific defects which have caused the damage is essential to proving your claim.
Establishment of the Causes of the Defects
- Continuing with the water infiltration example, assume that a failed sealant joint was identified as the responsible defect.
- Was the defect the result of improper maintenance by the owner, or is another party at fault? Were appropriate materials used? Were incompatible materials used together? Was the sealant joint assembly properly designed and constructed?
- It is not enough to establish that a certain caulk joint failed. The actual cause of the failure must be established.
Establishment of the Reasons for the Defects
- In the example, assume the wrong type of sealant was used, and the joint was not properly constructed.
- Why was the wrong material used? Was the wrong material specified? Did the contractor substitute materials without approval?
- Why was the assembly improperly constructed? Did the contractor take a shortcut? Did the architects not detail it properly? Was there inadequate supervision?
- The reasons the defects occurred must be determined in order to establish responsibility.
Establishment of Responsibility for the Defects
- Assume that in the example it was established that the contractor installed the wrong type of sealant without approval, and no specific architectural detail was drawn for the area of the failure.
- Did the architects sufficiently detail their construction documents? Would the leak still have occurred had the proper sealant material been installed according to manufacturer’s instructions, without a specific architectural detail? Did the contractor properly supervise the crew installing the sealant? Should the architect have reasonably detected the errors during a site inspection? Did the architect and contractor meet their respective Standards of Care?
- There may seem to be many parties which are to blame for a defect, but not all may actually be held responsible. The Standard of Care for each party must be established, and each party’s actions must be viewed in light of their Standard of Care. It is this analysis which establishes the responsible parties for building envelope failures.
Design or construction defects can be costly. Water damage can reoccur if the root causes are not identified. Decreases in energy efficiency due to defects will increase operating costs for the life of the building. The defects must not only be identified and repaired, but the specific defects, the causes of the defects, the reasons for the defects, and the parties responsible for defects must be established in order to recover economic losses. Types of Building Enclosure Investigations Review of the Building History
- Building history investigations can include discussions with the building owner, users, contractors, and maintenance personnel, as well as reviews of maintenance records. Your expert may prepare pre-survey questionnaires for the owner and other parties, as recommended in American national standard ASTM E2018 Standard Guide for Property Condition Assessments: Baseline Property Condition Assessment Process, as part of their building history research.
- The building history investigation must be the first step of all enclosure investigations, in order to define the issues at hand.
- Architectural, structural, and mechanical design drawings and specifications, if available, should be reviewed prior to any work in the field for all enclosure investigations. If applicable, construction contracts, change orders, requests for information (RFIs), shop drawings, as-built drawings, meeting minutes, construction progress photographs, commissioning reports, and building department records may also be reviewed.
- Visual inspections occur from a distance, whether at street level, from nearby buildings, at the roof, or from the interior. Binoculars may be employed. Additionally, infrared photography may be used to identify areas of wet insulation or heat loss through the building envelope.
- Hands-on inspections may be from the ground or from a scaffold, lift, or swing stage. In addition to observations, some field testing methods may be employed, such as sounding of concrete or masonry with a hammer, pull testing of sealants, or other non-destructive testing and evaluation methods, such as those described in American national standard ASTM E2270 Standard Practice for Periodic Inspection of Building Facades.
- Intrusive inspections will often include a contractor as well as the Forensic Architect. The Architect will direct the contractor to make openings in exterior or interior walls or to make test cuts in the roofing. The inspector will then be able to observe the underlying conditions and the actual construction of the subject assemblies.
- If structural deficiencies of the materials are suspected, samples may be taken for laboratory testing of the material’s structural properties. The standard SEI/ASCE 11 Guidelines for Structural Condition Assessment of Existing Buildings, published by the Structural Engineering Institute of the American Society of Civil Engineers, includes recommended evaluation procedures and testing for the material samples taken.
- All openings are repaired by the contractor immediately after the inspection.
In Situ Testing
- After Visual, Hands-on, and/or Intrusive Inspections, your Forensic Architect may recommend engaging a testing agency be brought in to perform in situ (“on site”) testing of the building enclosure performance. The testing agency would bring laboratory-type testing equipment and procedures to the building, to test performance criteria such as air leakage, water penetration, or sound transmission.
- Thermal and hygrothermal computer models can be used to simulate the expected heat flow (thermal) or heat and moisture flow (hygrothermal) characteristics expected of the building enclosure. In addition to this baseline model, defects identified during the exterior enclosure investigation can be included to model the existing conditions. Comparison of the actual energy performance to the baseline model and existing condition model provides a basis for quantifying energy loss damages.
In addition to a building enclosure evaluation, additional investigations and procedures by other experts, such as mechanical engineers may be required to address energy performance issues. What to Expect From A Building Enclosure Evaluations When your expert is engaged, the purpose of the evaluation must be fully defined so that your expectations and the expert’s expectations are aligned. The expert will develop an evaluation and testing program appropriate to evaluate the defects. Some scope items may be optional, depending on the results of initial evaluations. The evaluation report should:
- Identify scope and extent of the investigation.
- Identify areas which were inspected and by what means.
- Identify any areas that were not reviewed.
- Identify information the expert relied upon which was provided by others.
- Include observation, analysis, conclusions, and recommendations presented separately.
- Include photographic documentation.
- Include repair cost estimates and economic loss calculations, if appropriate.
- Be peer-reviewed by another qualified expert.
Who Should Perform Building Enclosure Investigations Building enclosure inspections should be performed by an experienced Architect familiar with building enclosure design, construction, and rehabilitation. Should in situ testing or computer modeling be required, an Architect well-versed in building science and building envelope commissioning should be engaged to direct the testing agency and interpret the testing results. For construction claims investigations, the Architect should also be experienced in identifying liability, quantifying damages, and assisting in resolving disputes. Building enclosure investigations may be part of an interdisciplinary approach to identifying and resolving building performance issues which may include investigations into the building’s structural, mechanical heating, ventilation, air conditioning, and controls systems design, operation, and maintenance.
Construction Claims Investigations
There is nearly infinite diversity to the scope of our construction claims investigations. The structure of our firm allows us to meet our clients’ needs by way of our breadth and depth. Among our construction professionals you can find architects with decades of project experience and a broad variety of engineers specializing in the niche disciplines specific to your investigation. Submit an inquiry or visit our Construction practice page for more information.