ISSUE 2/2002 ■ VOLUME 20 ■ NUMBER 2 Journal of architectural technology published by Hoffmann Architects, specialists in the rehabilitation of building exteriors. Troubleshooting the Building Envelope: Addressing CAUSES, Not Symptoms John J. Hoffmann, FAIA and Russell M. Sanders, AIA he various components of the building and the corrosive impact of acid rain Tenvelope—façades, roofing systems, and de-icing salts. The risk associated windows—and parking structures, plazas/ with deterioration in these structures is terraces/sidewalks, etc., inevitably severe; the threat of costly and time- deteriorate over time. The culprits? Water consuming lawsuits associated with infiltration, thermal expansion and driving and/or tripping hazards, contraction, improper construction and/or unacceptable. substandard materials, structural movement or stress, and age. What To Do When Trouble Strikes Maintenance of the building envelope is critical to preserving not only the structural Water infiltration can be counted on to integrity of a building’s exterior but also to exacerbate building envelope failures. protecting a building’s interior occupied Solutions to building envelope failures spaces; it serves as a barrier from the address CAUSES, not symptoms, and external environment. can be relied upon to keep water out of building envelope components in the Critical to maintaining the building future. envelope is the ability of the facility manager, property manager or building The key to successfully managing the engineer to recognize and address early building envelope is knowing what to indicators of deterioration. Costs do when trouble strikes. Temporary or associated with deferred maintenance cosmetic measures—band-aids, if you increase exponentially over time. The will—inevitably fail. The goal is to plan return on interior investments—to lobbies, and implement lasting solutions. offices, restrooms—will significantly diminish if water infiltration disrupts tenant activities When trouble strikes, the first task is to and causes irrevocable damage to ceilings, define the scope of work by: > Water infiltration, thermal expansion/ walls, windows and floor finishes. contraction, improper construction or · accurately attributing the nature and substandard materials, structural movement or Recognizing early indicators of extent of problem; stress, and age contribute to the inevitable deterioration is no less critical for parking deterioration of building materials over time. structures, plazas, terraces and sidewalks. · developing technically/aesthetically These elements suffer the damaging appropriate, cost-effective remedial effects of pedestrian and vehicular traffic, solutions; and, (continued on page 2) John J. Hoffmann, FAIA, Principal, and Russell M. Sanders, AIA, Director of Technical Services at Hoffmann Architects, are responsible for the technical quality and integrity of all projects produced by the firm. JOURNAL (continued from page 1) · establishing probable construction cost. are intended to separate us from the elements. Periodic surveys of exterior Contract Documents are developed for walls should be conducted to detect the designated scope of work, and bids indicators of deterioration. are solicited from capable and responsible contractors. Once construction is Brick Exteriors underway, the design professional ensures that the work being performed by the Bricks have been used as building blocks contractors is consistent with the work set for centuries, for structures ranging from > Efflorescence, white stains and/or build- forth in the Contract Documents. the adobe (mud brick) homes and up of white, crystalline structures, is caused missions in the southwestern United by the dissolution and surface deposition of By following these troubleshooting States to all manner of contemporary naturally occurring salts. guidelines, a building manager can avoid buildings. Common to all brick exteriors, the costly surprises that occur when however, is the necessity for consistent inappropriate and/or poorly implemented maintenance and repairs to ensure their indicators of deterioration. repairs fail. useful life for as long as possible. Figure 2, facing page, indicates types of Troubleshooting Exterior Walls Brick exterior walls should be checked mortar joints and their effectiveness in regularly for failed/aging mortar joints. preventing water infiltration. Note Be they brick, stone, concrete, metal, glass De-bonding, cracked/spalled brick, and that the recommended joints are those or any combination of these, exterior walls efflorescence/water staining are which direct water, a leading cause of building envelope failures, off of the exterior wall, as opposed to those Fig. 1 Relieving Angle Detail at End Wall which permit water to rest in the joints. Anatomy of an Exterior Brick Wall Flashing The basic components of brick veneer wall construction (refer to Figure 1) include the exterior face, the structure or “back-up,” and the cavity between the two; the flashing (which prevents the Brick passage of water into the structure from the joint); and the support angle. Typical causes of failure in this system include: · absent or inadequate flashing; Weeps · blocked water exit at flashing (blocked weep holes); · failed or inadequate soft joints at relieving angles; and, Sealant · failed mortar or expansion joints. Compressible Joint Stone & Pre-cast Concrete Exteriors Filler The proper care and preservation of sealant joints is key to preserving the Support Angle useful life of concrete and stone exteriors. 2 VOLUME 20 ■ NUMBER 2 How exterior joints are sealed, the consideration should be given to joint selection of sealant materials, and width limitations, preparation of surfaces installation considerations all play to improve bond, and exterior important roles in determining the temperature. Lastly, it is important to lifespan of a stone or concrete exterior evaluate/ensure the integrity of anchor wall. systems when conducting inspections of concrete and stone exteriors. Exterior joints must be properly sealed between: (Glass) Curtain Walls & Window Systems > Sealant failure between aluminum panels. · individual panels; When caring for (glass) curtain wall and window systems, a building manager · windows, frames and exterior walls; and, should: · any two or more building envelope · routinely examine window gaskets or components. sealant for splits, breaks or openings; Sealant materials should accommodate · replace failed gaskets or sealants that differential movement in various building have dried, cracked, shrunken or systems and bond properly to different otherwise exceeded their useful life; and, building materials. At installation, (continued on page 4) > Cohesive joint failure. Fig. 2 Types of Mortar Joints (In Profile) Concave/Rodded “V” Shaped Weathered Extruded Struck (Recommended) (Recommended) (Recommended) (Not Acceptable) (Not Acceptable) Flush/Plain Cut Flush & Rodded Ruled Raked Beaded (Acceptable) (Acceptable) (Acceptable) (Not Acceptable) (Not Acceptable) 3 JOURNAL (continued from page 3) Indicators of failure differ with the various types of roofing systems. They include: · in low slope systems: ponding, cracks, blisters, holes or splits; · in metal systems: pitting, corrosion, open seams/solder joint failure; and, > Ponding (water retention on the roof · in clay tile and slate roof systems: loose membrane) can occur in low slope roofing tile, broken tile, failed/deteriorated systems. fasteners. The most prevalent roofing application and repair errors are the results of > Glass curtain wall and window systems inattention to detail, the use of at a suburban corporate office park. incompatible or inappropriate materials, and improper installation. · inspect mullions for deterioration. Troubleshooting Plazas/Terraces Glass that appears “fogged” should > Note cracks in these damaged ballast not be neglected. It may be Plazas/Terraces often serve as popular pavers (in a low slope system). symptomatic of a compromised gathering places, for both building tenants thermal seal. and area pedestrians. These heavily trafficked areas may incorporate Troubleshooting Roofing Systems landscaping and lighting design, reflecting pools and fountains, and may even Whether low slope or steep slope, showcase the work of area sculptors. At regardless of materials and/or the hands of Mother Nature, plazas/ construction, all roofing systems terraces are continuously exposed to the inevitably deteriorate over time. full force of the elements. > Open seams/solder joint failure are indicators of deterioration in metal systems. During a roof inspection, problem What about plazas will plague you? Proper care during application of roofing areas should be examined to detect materials is critical to preserving a roof’s the root causes of deterioration and Plazas over occupied spaces are part of useful life. to determine the most effective repair the building envelope. While water is solutions. Deterioration increases clearly the enemy of any part of the exponentially over time. To put it building envelope, it is particularly harmful simply, the longer it sits, the more to horizontal surfaces. Standing water on damage it will do to the structure. horizontal surfaces, on plazas and terraces, Early detection and pro-active accelerates deterioration. maintenance and repairs enable a building manager to avoid more costly Inadequate drainage and prematurely roof repairs and/or replacements in failed waterproofing membranes are the future. detrimental to a