Edward J. Stewart, RRC Jon F. Lindberg, PE Gale Associates, Inc, Weymouth, Massachusetts ABSTRACT A major responsibility of a facility manager is to ensure that his or her building is as watertight, energy-efficient, and safe as possible. This often means investigating and evaluating the building envelope (roof, walls, windows, waterproofing, and struc¬ ture) to define and resolve existing problems as well as to eliminate future problems, thereby extending the service life of the building. Whether an owner is investigating a leakage problem themselves or he’s hired a consultant for a larger-scale investigation, this approach can serve as a guide to determining and repairing problems with the building envelope. SPEAKER Edward J. Stewart, RRC, is an associate with Gale Associates, Inc. He is a member of RCI, NRCA, the International Concrete Restoration Institute (ICRI), of the American Society for Testing Materials (ASTM), and the U.S. Green Building Council. Contact Information: Phone – 781-335-6465; E-mail – ejs@gainc.com Stewart and Lindberg – 166 Proceedings of the RCI 23rd International Convention
A major responsibility of a facility manager is to ensure that his or her building is as water¬ tight, energy-efficient, and safe as possible. This often means inves¬ tigating and evaluating the build¬ ing envelope (roof, walls, win¬ dows, waterproofing, and struc¬ ture) to define and resolve existing problems as well as to eliminate future problems, thereby extend¬ ing the service life of the building. Whether an owner is investi¬ gating a leakage problem them¬ selves or he’s hired a consultant for a larger-scale investigation, this approach can serve as a guide to determining and repair¬ ing problems with the building envelope. RESEARCH A BUILDING’S HISTORY BEFORE DETERMINING ITS FUTURE Collect Historical Data Historical data will assist in determining the original design intent, possible construction vari¬ ations, and recurring problematic areas in the building. Historical information includes: • Design documents, speci¬ fications, plans: any infor¬ mation that helps define how the building was designed or constructed. • Codes and standards that were applicable at the time of the building’s construc¬ tion. • Test reports on any kind of materials or systems, such as window systems, ma¬ sonry components, roofing systems, etc., to compare with the original design documents. • Construction documents (i.e., change orders, in¬ spection reports, shop drawings, as-built draw¬ ings). • Local practices or what was normally installed by contractors at that time and in that region (e.g., maybe they had trouble installing an envelope sys¬ tem or component that they had little or no expe¬ rience with). Determine the Original Design Intent and Effectiveness Figuring out the original design intent is also key in deter¬ mining what could be causing problems with a building enve¬ lope. For example, investigating problems with the roof system would include reviewing the structural, thermal, drainage, and vapor drive to understand perfor¬ mance requirements. For win¬ dows, the infiltration require¬ ments, thermal-resistance levels, and the structural capabilities of the window openings necessary to keep the windows in place and under specific wind loads are nec¬ essary. When examining walls, the required thermal resistance, the structural requirements, an¬ ticipated moisture infiltration, and the drainage system are criti¬ cal to understand. In addition to the design intent, the original design effec¬ tiveness should be considered. Was this design appropriate for the location of the building? Can it perform as intended? Is the building in a high-exposure area or protected from a harsh envi¬ ronment? Examine the Building’s Service History A full understanding of how the building is serving its occu¬ pants is important to all facility managers. Occupant interviews regarding active leaks provide valuable information during a building evaluation. Maintenance reports will provide useful infor¬ mation regarding where the build¬ ing has been repaired and where the problem areas exist. All of this information helps the investigator better understand the condition of the building and determine the areas that need to be more close¬ ly reviewed. The next step is to perform a thorough leak audit of the build¬ ing to determine where leaks are occurring and under what condi¬ tions. The leaks can be affected by weather. If the leaks occur only after a wind-driven rain, then it could indicate more of a wall leak¬ age problem as opposed to a roof leakage problem. If they are affected by temperature, then it could be a condensation/ HVAC issue. PERFORM A FIELD INSPECTION One of the most important aspects of performing building envelope evaluations is the field inspection. After compiling the available design documentation and researching the building’s service history, it is necessary to examine the existing conditions. The field inspection operations will serve to complement and expand the data obtained from the previous service history and Proceedings of the RCI 23rd International Convention Stewart and Lindberg – 167 design documentation, as well as indicate variations between origi¬ nal design and construction. The scope of the field inspec¬ tion will establish the types of field procedures that will be required to obtain the necessary information for a complete build¬ ing envelope evaluation. Based on the information compiled to this point, the areas for inspection can be carefully selected to obtain a sample of potential building defi¬ ciencies. Access Methods There are several access methods that may be utilized to reach difficult wall /building areas to gather data: • Two-Man Ground Lifts – Two-man ground or rolling lifts can double as obser¬ vation and testing plat¬ forms with the ability to relocate quickly and con¬ form to irregular building geometry. Accessible land directly adjacent to the building is necessary for rolling lifts. • Swing Staging – Swing staging, like the two-man ground lift, offers a suit able platform for observa¬ tion and testing but is more suitable for straight vertical drops with a flat building geometry. Roof access is required to set up and move the swing staging. • Rappelling – Rappelling, or industrial rope access, is a method borrowed from mountain climbers that allows the investigator to safely access structures by descending and ascending suspended ropes. It is an inexpensive, useful method of vertical building access to perform evalua¬ tion and light test proce¬ dures, with the ability to Figure 1 – Inspection of wall using swing stag¬ ing. relocate quickly. • Ground Observation – Ground observation with the use of binoculars is useful to spot potential problematic areas, or sim¬ ply to verify or acquire quantities of components. High-powered binoculars and vantage points such as adjacent buildings or roof levels will help to improve the field data col¬ lected. Identifying the Defects Proper defect identification will help to determine the re¬ quired types of repair, aid in prop¬ er repair material selection, and reveal the influences that are con¬ tributing to the deterioration. It is important to acknowledge which factors have caused degradation of the building and its compo¬ nents and how one deficiency and its intended repair may influence or amplify another. Careful and thorough defect identification is critical to obtain long-lasting, quality repairs. It is necessary to eliminate the cause of the defect and not solely treat the symptom. Correlating the interior leak audit with exterior defects assists in determining the cause and ori¬ gin of various problems because it narrows down the exterior testing areas. It also helps managers pri¬ oritize repairs and a replacement sequence of work. Quite often, due to budget limitations, man¬ agers cannot rectify all of the building’s problems. Knowing the cause and origin of the problems and the extent of moisture infil¬ tration can assist in prioritizing the repairs to fit a particular bud¬ get. TESTING METHODS The objective of field testing is to correlate paths of moisture infiltration with the observed damages. Anyone can observe moisture coming into a building during harsh weather events, but the most reliable way to test is to actually recreate the leakage in a controlled manner so that the path of the leaks may be traced. Stewart and Lindberg – 168 Proceedings of the RCI 23rd International Convention Testing also allows verification of the hypothesis for the cause of leakage. There are many different types of testing that can be used during the investigation to suit a particu¬ lar building’s needs. These testing categories include: • Non-destructive testing • Destructive testing • Laboratory testing NON-DESTRUCTIVE TESTING Non-destructive testing uses a variety of non-invasive tools. This type of testing requires little to no damage or interference to the building envelope. The various methods of non-destructive test¬ ing include: • RILEM Tube – This cali¬ brated device is adhered to exterior masonry walls to determine the porosity and condition of various components, including brick masonry units, mor¬ tar joints, head joints, and embedment joints. • Water Spray Rack (ASTM El 105) – This test simu¬ lates a wind-driven rain condition on a facility. It can assist in determining the specific cause and ori¬ gin of moisture infiltration when it is used to test independent components of the envelope. Water spraying a large area in an uncontrolled fashion will not reveal specific causes of moisture infiltration. • Hose Spray Test (AAMA 501.2) – This test method also simulates wind-driven rain in small, segmented areas using a standard garden hose that has a calibrated nozzle with a pressure gauge attached. The spray is directed at a specific joint, crack, or defect to reveal potential Figure 2 – Performing a RILEM tube test to determine porosity of a masonry wall. moisture intrusion. • Differential Pressure Test (ASTM Ell 05) – A pressure chamber is typically con¬ structed on the interior of the facility at a specific location to test moisture drive through an assembly or component. The assem¬ bly or component is sub¬ jected to a negative force while a spray rack test is directed simultaneously at the assembly to draw the moisture into the facility simulating a negative pressure under a winddriven rain condition. • Infrared Thermography – Infrared thermography photographs the building exterior to determine the locations of wet compo¬ nents. Components such as insulation and sheath Figure 3 – Water spray test used to locate source of leak. ing, will act as heat sinks if they are contaminated with high levels of mois¬ ture. During the day, moist and dry components absorb heat. At night, the moist areas release the heat much slower than the dry areas. By reading the heat signature, infrared thermography will help expose the moist problem areas. Small test cuts are required to verify mois¬ ture-contaminated areas. Soundings (ASTM D4580) – There are different ways to perform sounding tests, including the hammer tap test. In this test, a 16-oz hammer is tapped against concrete for sound. A hol¬ low sound indicates areas in which the concrete has separated from the rein¬ forcing steel, typically due to exfoliation or corrosion of the steel. Another method of sounding is chain dragging a heavy 15-ft link chain along a concrete surface to listen for hollow sounds, indicat¬ ing defective concrete. This method is commonly used on parking garages and loading docks to cover larger areas effectively. Pachometer Survey – A magnetic device used to locate embedded steel reinforcement and help determine the concrete cover over the reinforce¬ ment. Generally, the pachometer is fairly accu¬ rate when measuring 1/4- in to 3-in thick concrete cover and when reinforc¬ ing placement is not too congested. Polysheet Tapedown – This test determines the pres¬ ence of moisture coming through a concrete sur¬ face, typically a slab-on- Proceclin^s of the RCI 23rd International Convention Stewart and Lindberg – 169 Figure 4 – Air infiltration test. face of a window to ob¬ serve the smoke and dust particles for air infiltration through the assembly. Moisture Meter – A Delm horst meter is a simple digital device that detects the presence of moisture in various building compo¬ nents. This test is typically accompanied by a gravi¬ metric analysis (oven dry ing of samples), which is used to confirm the re¬ observe concealed condi¬ tions. DESTRUCTIVE TESTING When the main objective is to determine the existing composi¬ tion and configuration of con¬ cealed assembly conditions, destructive testing is warranted. The most common methods of destructive testing are test cuts and borings. Roofs grade type of assembly where the typical problem is tile or membrane sepa¬ ration from the floor. A 2-ft x 2-ft section of polyethyl ene is sealed to the con¬ crete with duct tape and removed 24 hours later. If there is moisture beneath the polyethylene, it is a good indication that there is a vapor drive through the concrete section. • Glass-Slide Epoxy or Crackometer – This device is sealed in place over a crack and periodically checked to determine if any movement has occurred. If it has, the glass will crack or the meter will record move¬ ment. • Optical Illuminated Boro¬ scope – A boroscope requires a 5/8-in diameter pilot hole through an exte¬ rior wall system to allow the cavity walls of brick veneer, stud wall backup of exterior insulated finish systems (EIFS), or other types of constructions to be observed without largescale destructive testing. • Smoke/Dust Tracer – A simple and useful test, the smoke/ dust tracer helps to find air infiltration. It is moved across the interior suits of the Delmhorst meter. Test cuts in the roof assembly are necessary to determine the • Flashlight and mirror – These everyday, simple tools can be very useful. Placing the mirror into the plenum or behind diffi¬ cult-to-access areas with the flashlight will help Figure 5 – Performing a boro¬ scope analysis to view wall cavity and related back-up wall components. condition of the underlying insu¬ lation and substrate. Cutting into the system will help to verify if roofing problems are causing a corroded steel deck, or a spalled and cracked concrete deck, etc. Test cuts will also expose the asbuilt configurations of flashing components, roof-to-wall loca¬ tions, curb locations, etc. This information is critical to the appropriate remedial design in order to specify appropriate flash¬ ing details. Exterior Walls Test cuts on exterior walls are a useful tool when trying to iden¬ tify the origin of moisture infiltra¬ tion. For masonry walls, it is most effective to make test cuts at win¬ dow heads and sills, and at any through -wall flashing locations that may be suspected of allowing moisture intrusion . Masonry test cuts can ex¬ pose defec¬ tive throughwall flashing that is al¬ lowing mois¬ ture intru¬ sion. Test Figure 6 – Using a smoke/dust tracer to find air infiltration. cuts will also help deter¬ Stewart and Lindberg – 1 /0 Proceedings of the RCI 23rd Internationa/ Convention mine the underlying conditions of the steel components in wall sys¬ tems, which include wall ties, re¬ inforcing steel, sub-steel columns, etc. Gathering Samples for Laboratory Testing Destructive testing is also used to obtain sampling for lab analysis. Sample sealants, coat¬ ings, painted finishes, roofing materials, etc. can be sent to a laboratory to determine the pres¬ ence of lead or asbestos. Samples of masonry or concrete can also be used for different laboratory analyses to help identify causes of moisture/air infiltration (descrip¬ tions of these analyses follow). LABORATORY TESTING Laboratory testing will help obtain a better understanding of existing material types, presence of contaminants, possibility of hazardous components, and pro¬ vide valuable information con¬ cerning proper surface prepara¬ tion, material selection, and implementation of repairs. The following laboratory tests are some of the more useful when performing building envelope evaluations: • Gravimetric Analysis – This is basically a mois¬ ture content test. After weighing and recording the in-situ existing sample, completely dry it in an oven and re-weigh it. The weight difference indicates moisture content and is particularly useful for insulating materials. Testing moisture contents of samples is critical to verify results from non¬ destructive moisture scans. • Asbestos and Lead – Test the paint, sealants, plas¬ ters, roofing materials, etc. to determine if asbestos or lead is a component of existing materials. This is helpful to provide an accu¬ rate cost estimate for re¬ mediation of hazardous materials. This simple test is inexpensive at any test¬ ing lab and allows the proper remediation meth¬ ods to be specified to avoid costly change orders. Petrography – Petrography determines the “make-up” of concrete. This test will indicate the size and type of aggregate, air/ void ratio, type of cement, and general mix design data of the concrete. Any materi¬ als testing lab will perform this test; however, it is expensive and time con¬ suming. Compression/ Tension – By determining the actual compressive strength and modulus of rupture for the concrete, a similar strength characteristic of new repair material may be selected to maintain appropriate section behav¬ ior and extend repair life. Air Entrainment – Provides an indication of the exist¬ ing concrete’s durability and freeze-thaw resis¬ tance. Air entrainment is generally indicated by petrography. Presence of Carbon¬ ization – This is com¬ pleted by spraying a solution of phenothe lene on the concrete substrate and record ing the depth of the solution’s color change. This will indi¬ cate to what depth carbon dioxide has progressed into the concrete. Carbon di¬ oxide will degrade the cement matrix of the concrete and lower the pH level of the concrete. The passivation layer sur¬ rounding the reinforce¬ ment is then destroyed, allowing corrosion of the reinforcing steel. Corro¬ sion of reinforcement by carbonization usually occurs over a broad area. Chloride Ion Content – Chlorides from marine atmospheres or mists from road salts entering the concrete substrate, and salts originally introduced to the concrete via admix¬ tures or aggregates will allow an accelerated corro¬ sion of reinforcing steel, usually at concentrated or specific locations. The chlorides are not con¬ sumed in the corrosion process, but rather act as catalysts in the corrosion process. The corrosion will progress along the rein¬ forcing bars, causing con¬ crete debonding, cracking, and spalling. Reinforcement Placement, Depth, Quantity, and Type – This information may be established with the use of a pachometer or similar electronic metal detector. It is useful in determining required steel replacement Figure 7 – Steel reinforcement cor¬ rosion resulting from high chlo¬ rides and presence of carboniza¬ tion. Proceedings of the RCI 23rd International Convention Stewart and Lindberg – 171 and structural capacities during engineering analy¬ sis phases. ENGINEERING ANALYSIS Using field-obtained informa¬ tion, laboratory results, and col¬ lected data from service history and the original documentation, a comprehensive engineering analy¬ sis should be performed. The engineering analysis should include an assessment of field and laboratory data, structural analysis, and the following: • Thermal analysis • Drainage analysis • Vapor drive analysis • Fire rating requirements • Cost estimating (often the most important compo¬ nent of engineering analy¬ sis for the building manag¬ er) General considerations for the repair of defects and replacement of components should include the following: • Determine the effect, if any, the repairs have on the structure, surround¬ ings, and operations of the building. • Ensure proper preparation of surfaces to be repaired, and provide chemical and mechanical bonds for new materials. • Material selection should include an understanding of performance limitations and should rely on the products’ past acceptable performance. Material selections should include consideration of the fol¬ lowing: • Compatibility • Maintenance • Life cycle A THOROUGH EVALUATION = LONG-TERM COST SAVINGS An in-depth evaluation of the building envelope enables the architect/engineer to develop accurate specifications for con¬ tractor bidding, which will also be used during construction. The quality of the initial field evalua¬ tion reflects directly on the quali¬ ty and performance of repairs as outlined in the specification docu¬ ments. A thorough investigation also promotes an efficient design specification, thereby reducing the possibility of increased costs via change orders, due to unfore¬ seen conditions. The time and expense to per¬ form an initial, well-focused eval¬ uation will save the building owner/manager money in the long run and result in repairs that extend the service life of an impor¬ tant asset: the building. Stewart and Lindberg – 172 Proceedings of the RCI 23rd International Convention
