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,

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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

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· 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.

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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)

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(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 · 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 plaza’s useful lifespan. Ponding, water stains, cracks, spalls and Successful design solutions for roofing heaved pavers (which create tripping systems allow for differential hazards) are the indicators of trouble. > An historic mansard roof (having on movement, properly integrate/curb Protection of the waterproofing each side a steeper lower part and a rooftop equipment, and provide for membrane and sufficient drainage are the shallower upper part) with terra cotta tiles. foot traffic. solutions.

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Fig. 3 Plaza Drain Drain Cover Plaza Paver

Pedestal

Underlayment Mat

Rigid Board Insulation

Drainage Composite

Waterproofing Membrane

Water should be allowed to drain both land is at a premium, parking structures at the wearing surface and beneath the are an integral part of the commercial plaza surface at the membrane. landscape. They can be constructed of Drainage may occur at varying degrees pre-cast concrete, cast-in-place concrete, or of slope: paved surfaces with tables and steel with a concrete deck. chairs should be more level, while it is generally recommended that drainage at Parking structures deteriorate more the membrane should occur at 1/4” per rapidly than other built structures as they foot. In order for drainage systems to suffer the damaging effects of vehicular remain effective, drains must be traffic and the corrosive impact of acid rain > Plazas/terraces often incorporate seating, consistently maintained. They should be and de-icing salts. This is in addition to planters, and lighting design, all of which must periodically checked and cleared of water infiltration, thermal expansion and be considered when planning maintenance debris. contraction, improper construction and/or and repairs. substandard materials. The bi-level plaza drain assembly in Figure 3 above shows a loose laid Symptoms of water infiltration in parking assembly, but the same results are structures include efflorescence, cracks and achievable with pavers in a mortar spalls.Building managers should beware of setting. Typical trench drains are not cracks on surface slabs that permit water manufactured as bi-level drains, causing to enter the concrete. But it should be water to stand at the membrane level. remembered that deterioration begins within the slab, out of view. Damage > Debris should be cleared of drains to visible from the deck is often only the tip Troubleshooting Parking Structures ensure their effectiveness. Note cracks which of the iceberg. permit water entry.

In a society where drivers abound and (continued on page 6)

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(continued from page 5) Case in point: when cracks (which can instrumental in developing appropriate develop on the top surface for any repairs that go beyond surface damage number of reasons) permit water to and correct deterioration at its core. enter the concrete, the steel reinforcing bars that are embedded within the Troubleshooting Historic & Landmark concrete for stength begin to rust. As Structures the steel rusts, it pushes the concrete away, causing it to chip and spall—risking Historic/landmark building exteriors are damage to vehicles and injuries to often constructed with materials and > Large, stainless steel replicas of automobile people. techniques uncommon to contemporary hood ornaments adorn the landmarked construction and can present . Over the years, roofing maintenance/rehabilitation challenges. It is mastic, sealant and other incompatible often essential to develop a concise materials were used to make repairs, all of approach to address maintenance needs, which exacerbated negative conditions. remedial repairs, and modifications or restoration work to the building envelope.

> Spalls, laminations that break off due to Other considerations for the successful corrosion of reinforcement/embedded management of historic/landmark items, are among the indicators of failure in structures include: parking structures.

> · landmark status (national or local) and related rehabilitation guidelines/ Pro-active Maintenance Is Key restrictions;

Parking structures require consistent · local building codes; maintenance. Conducting regular visual examinations to identify potential · primary building function and tenant problem areas goes a long way toward requirements; and, preventing the development of negative conditions. And, preventative · budget. maintenance techniques, such as the > Intricate patterns and decorative application of an appropriate coating or A tremendous financial burden can be elements can present challenges when sealer to protect new decks from placed on the building owner of a rehabilitating historic structures. corrosion, can be effective. historic/landmark structure. The proper remediation or restoration of the exterior Conclusion When repairs become necessary, the may cost two to three times the value of extent of the damage must be the building. Failure to identify and address building determined and the area properly envelope “hot spots”—portents of quantified to effect lasting solutions. This Unique Materials & Techniques deterioration—will ultimately result in can be accomplished using simple significant expense to building owners. methods such as chain dragging or Construction materials that are more People, the power of nature, and the sound tapping the surface to identify prevalent in historic structures than in passage of time can be relied upon to delamination. More extensive testing of contemporary structures include terra adversely impact the building envelope. concrete may be needed to determine cotta, tile (mosaic, clay, ceramic), and Early detection, however, can be a its integrity and the true nature and decorative/ornamental grating (iron, powerful weapon in the fight against extent of deterioration. Tests that aluminum, stainless steel). Construction building envelope deterioration; it allows measure compressive strength, depth of techniques include intricate patterns for the development of pro-active carbonation (which reduces the natural within brick, stone, terra cotta, and tile; maintenance and repair programs that ability of concrete to protect embedded narrow joint widths among brick and minimize tenant disruption and maximize reinforcement steel), and chloride ion stone; and obsolete structural/anchor a building owner’s return on investment. content (from road salts) can be systems.

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Building Envelope Rehabilitation Trinity College Fairfield, Hartford, Connecticut Facade, Roof & Parking Garage Hoffmann Architects has developed and Rehabilitation Master Plan Rehabilitation implemented building envelope rehabilita- tion solutions for a number of its One Beacon Street United Nations Complex corporate, industrial, academic, municipal, Boston, Massachusetts , New York and ecclesiastical clients, including: Parking Garage Repair & Plaza Dome & Roof Rehabilitation Rehabilitation United States Capitol Complex* New York, New York The Bank of New York Washington, District of Columbia Facade & Roof Rehabilitation New York, New York Restoration Roof & Facade Rehabilitation The Goodwin Hotel* Xerox Corporation Headquarters Hartford, Connecticut 25 Sigourney Street Stamford, Connecticut Facade & Roof Restoration Hartford, Connecticut Facade Rehabilitation (State of Connecticut) (continued on page 8) Verizon Communications Building Envelope Rehabilitation & New York, New York Re-Roofing > Verizon Communications Headquarters Facade & Roof Rehabilitation New York, New York. Smithsonian Institution Washington, District of Columbia New York, New York Copper Roof Restoration Roof & Facade Rehabilitation National Museum of American Art, National Portrait Gallery & J.P... Morgan Chase & Co., Incorporated Archives of American Art New York, New York Building Envelope Survey & Facade Chrysler Building* Restoration New York, New York 23 Complex Spire & Facade Restoration 15 Pfizer,,, Inc... World Headquarters New York, New York 43 Exchange Place Facade & Roof Rehabilitation

IBM Corporation School Construction Poughkeepsie, New York Authority Roof & Masonry Rehabilitation New York, New York Building Envelope Rehabilitation Complex New York, New York General Electric Company Exterior Restoration Corporate Headquarters

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JOURNAL is a publication of Hoffmann Architects, specialists in the rehabilitation of building exteriors. The firm’s work includes investigative and rehabilitative architecture/engineering services for the analysis and resolution of problems within roofs, facades, glazing, and structural systems of existing buildings, plazas/ terraces, and parking garages. Please send news, technical information, address changes, or requests for free subscriptions to Editor, Hoffmann Architects JOURNAL, 432 Washington Avenue, North Haven, Connecticut 06473. For answers to specific questions or for information on the services Hoffmann Architects offers, please contact Sandra Matheny at

> Hoffmann Architects designed an award-winning program to restore the Queen Anne-style (203) 239-6660. Goodwin Hotel, originally constructed in the 1880s. 432 Washington Avenue North Haven CT 06473 (continued from page 7) 203 239-6660 Foxwoods Resort Casino The Hartford 500 Fifth Avenue, Suite 830 Mashantucket, Connecticut Corporate Headquarters New York NY 10110 Rehabilitation Hartford, Connecticut 212 789-9915 Grand Pequot Parking Garage Building Envelope Rehabilitation, Master 1001 Connecticut Avenue NW, Suite 825 Great Cedar Parking Garage Plan, Facade Restoration & Roof Washington DC 20036 Replacements 202 530-1100 Prudential Insurance Company For more information on the Eastern Operations Office Lincoln Center for the Performing Arts topics discussed in this article, King of Prussia, Pennsylvania New York, New York visit us on the web at Building Envelope Rehabilitation Roof & Facade Restoration www.hoffmannarchitects.com, Metropolitan Opera House or contact us at 1166 Avenue of the Americas Avery Fisher Hall [email protected]. New York, New York Vivian Beaumont Theatre Editor & Graphic Services: (Marsh & McLennan Headquarters) Maryellen Apelquist Plaza, Facade & Roof Rehabilitation * Denotes an award-winning project.

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