Chamberlin LTD

Identifying Building Envelope Problems

noemail@chamberlinltd.com — Wed, 27 Dec 2006 20:00:00 GMT

By Mark K. Howell

By definition, "envelope" is an encapsulating covering, such as an outer shell or membrane. In simple building terms, it consists of the roof, above-grade wall system and the below-grade wall system. An envelope's purpose is to provide protection from external elements, which in building construction means protection from moisture, air and temperature ingress and egress.

The definition sounds simple enough, but in reality--because of the thousands of complex products and systems specified and the multiple trades involved--the chance of error is high. As complex and intricate as the building envelope seems to be, how can you tell if building envelope is going to have or is already having problems?

Proactive Investigations

In a perfect world before clients purchased a structure, they would engage a professional with building envelope knowledge to inspect the structure and determine the potential building envelope investment that may be required. Clients typically look at the roof, but rarely go into the remaining elements of the building envelope. With good information from an investigation, a client can make a prudent business decision prior to purchasing a structure. Armed with this information, he can renegotiate the price, accept the risk while being aware of the financial needs, or walk away from the deal.

Unfortunately proactive investigations are still rare, especially when the economy and real estate markets are booming and deal making is fast and furious. A large majority of calls are from clients who have recently acquired structures, new property managers, new condominium board members, new church business managers or new building engineers--each of whom has just taken over a property and found that something is leaking or falling off the building. Regardless of when and whom you get the call from, what is a good way to tell if the building envelope will have problems?

Obviously you have to see the building in person, which then brings up the question: How closely do you need to look? A good starting point is covered by the ASTM E2270 Standard Practice for Periodic Inspections of Building Facades for Unsafe Conditions, which defines the levels of facade inspections to apply to a building. These definitions can be adapted and applied to the building envelope. The ASTM guidelines define a general inspection as observation from greater than six feet and detailed inspections as a visual observation from less than six feet. Typically, the decision for a general inspection has been made because the detailed inspection is too expensive, would take too long, or a report is needed in a short amount of time.

So, we arm ourselves with a building envelope investigator's tool kit, including but not limited to: a good carry bag (I use a hiker's waist pack), a tape measure, rolling wheel, camera, notebook, several color pens, markers, duct tape, a voice recorder and, most important, personal protection equipment, including a hard hat, safety glasses and a pair of gloves.

The general inspection can be broken down into four basic steps:

Initial Walk About
Knowledge Gathering
Interior Symptoms
Exterior Signs

Initial Walk About

I like to begin with a basic tour of the structure before I really get into the details of the next three steps. I title three pages of my notebook at the top--one for the wall system, one for the roof and one for the wall system below grade. I use these pages as my initial note pages to start the documentation process and usually skip using the camera until I get into Steps 3 and 4. This step is used to get familiar with the structure so that if and when I get to see the drawings, I have a mental picture of the building.

Beginning with the wall system, I walk around the structure to get an understanding of the shape and makeup of the structure, materials used, as well as any features like balconies, cornices or ornamentation. Also, I check to see how the building is terminated at grade. I then head to the roof to see the layout--if it has a parapet, how the roof is terminated to the parapet, how the roof is accessed, and the roof system type. Finally, I head to the below grade area of the structure, looking for sump pumps, smelling for dampness and determining the foundation wall construction. Once I have made this brief walk about, I go to the building manager, property manager, business manager, etc., to start the next step: Knowledge Gathering.

Knowledge Gathering

I start this step by asking for a set of drawings. Sometimes this is a challenge. I usually let them know I am going to need thses before showing up so they can find them, organize them, unbury them, etc. It is hoped, they have drawings to review; but with older structures these may not be available. In this case, in order to access some of the history of the structure, you interview management, maintenance staff and tenants, in addition to reviewing the maintenance and project file. Also, ask for any warranties; usually you get one for the roof but also ask for manufacturer warranties for the window systems and the below-grade waterproofing system.

Being more comfortable with facades, I usually flip to sections to find details (or the lack thereof) on the wall systems. First and foremost, I try to identify the wall system as a barrier wall or a water-managed wall (see ASTM 2128 Standard Guide for Evaluating Water Leakage of Building Walls). If it's not clear or if it seems to be questionable, that jump-starts my suspicions on the design details. Next, I check out the details. If a lack of details are pulled out of the wall sections to show how to create terminations, penetrations and changes of plane for all of the particular wall system building materials, it immediately throws up a flag. Unless the project had a high level of quality field craftsmen or really good inspectors, there may be some challenges in the way field decisions were made in order to make these details work. Also, part of the drawings asked for are the shop drawings, especially for the windows if there is a curtain wall. From the window shop drawings, try to determine how the window system is managing water. A lack of wall details or the lack of shop drawings at any time makes Step 3, Interior Symptoms, more intense.

For the roof, I always look at the roofing system type and check if the construction drawings of the roofing system match the existing conditions. If they don't, has there been any modifications? Also if there has been a modification, what, if anything, has been done to the parapet wall? Because parapets are exposed to weather on three sides, there is a greater chance of them having problems, especially if the modifications did not take into consideration the ordinal design intent. Identify the number of drains and whether there is an appropriate roof slope to drain. How the through wall scuppers are detailed always should be reviewed, especially if the scupper outlet is directly at the vertical expansion joint. Last, I try to locate the system specified for the below-grade waterproofing and see if any details were made on termination, penetration and changes in plane.

Interior Symptoms

At this point if the building management has any knowledge of the interior water infiltration and/or severe cracking of interior finishes, now is the time to take the observations you gathered in Step 1 and Step2 in order to identify symptoms in the interior. A brief list of symptoms to look for is:

Staining of the interior wall surfaces and/or the wall system above the ceiling tiles (Figure 1)
Water-damaged insulation above the ceiling tiles
Stained ceiling finishes
Water-damaged window soffits, jambs and sills (Figure 2)
Water stains on the floor finishes, including rust stains from excessively wet steel stud base plates
Peeling of wallpaper
Cracking of interior finishes
Stains / dirt in operable window tracks
Water stains at the perimeter of the AC units
Mold

Document the location of these interior symptoms so that during Step 4, Exterior Signs, you can potentially see if there is a direct correlation. Specifically regarding water infiltration, water does travel; and many times, symptoms are not simply on the exterior of the building. Here is where ASTM 2128 Standard Guide of Evaluating Water Leakage of Building Walls is a tremendous resource.

Exterior Signs

Once you have gathered the information from the previous three steps, you will have a better understanding of what to focus on during the inspection of the exterior signs. The obvious big three are buldging, spalling and cracking. Other than the obvious, here is a brief list of other exterior signs to look for:

When the wall system has a cavity wall but you cannot see the flashing
Weep holes are caulked shut
Weep tubes or weep wicks were used
The roof runs up the back of the parapet wall (Figure 3)
Rust marks are present at imbedded steel locations
Railing posts are set in concrete pockets
Cracks go through the masonry and the mortar
Capstones have craze cracking
Capstones have inside and outside bed joints and the cross joints caulked shut
Spalling brick
Glazed brick shattered with effloresce stains
Cracking through EIFS lamina (Figure 4)
Post-tensioning ends with rust bleed out
A white haze on a brick cavity wall
Efflorescence from cracks in concrete or masonry
Grade is sloped toward the building
Rain water conductors cut off and run out on grade
Horizontal rust limes in mortar joints
Discolored stone or masonry
Racked windows and doors
Rotted or rusted door and window frames
Signs of condensation on glass
Excessive mortar joint popping
Smeared caulking on mortar joints
Step cracking off of steel lintels
Glued down carpets on exterior horizontal concrete surfaces
Painted and/or caulked terra cotta
Glass-to-metal glazing has turned into gum or has shrunk from the window frame
Compressed building sealant at expansion joints
Face-sealed curtain walls or window systems
Surface alligatoring of the roof membrane
Roof seam splits
Roof surface applied termination bar to a cavity wall (Figure 5)
Overall roof drainage
Incomplete expansion joints (Figure 6)

If any of these signs match up with any symptoms determined in the previous steps, there is a very good chance that the building envelopes faces some challenges. The exterior signs without interior symptoms, do not mean there is not a challenge, but it's just a matter of time. In most cases, the interior symptom will occur at some point in the life of the structure, so it is important to continue to monitor these conditions.

In most cases, the obvious building envelope problems are easy to identify. In order to identify the not-so-obvious signs, especially if the interior symptoms have not occurred or have not been identified, experience in the restoration of building envelope deficiencies is priceless. Combine this with the knowledge of architectural details, engineering basics, good waterproofing practices, as well as an inspection plan as outlined above, and the client will have the best possible information about the building envelope. This information can be used as a tool to purchase a building, create capitol projects or develop a maintenance plan.

Mark K. Howell is a recognized leader in concrete and masonry maintenance repair industry and has been involved in the investigations and restoration of many comtemporary and historic structures during the past decade. He is employed with Stuctural Preservation Systems in Baltimoore, Md., and can be reached via mhowell@structural.net

This article was printed in the Summer 2005 Issue of SWRI's Applicator magazine.

27-Dec-06 2:00 PM

Sealing Stadium Expansion Joints: A New Process Yields Watertight Results

noemail@chamberlinltd.com — Thu, 15 Jun 2006 15:00:00 GMT

By Lester Hensley, President and CEO of EMSEAL Joint Systems, Ltd.

Most stadiums leak at expansion joints. Owners cringe at the truth and spend thousands, even millions, of dollars each year to repair leaks. The rare exceptions--stadiums completed with watertight joints--are characterized by a design and build process that involves a shift in the traditional way stakeholders relate and execute their work. This process must begin early in the stages of design and planning, and continue until construction is complete.

How can stadium owners ensure that their facility will be leak free? There are several steps tht if followed throughout the project, will ensure the stadium remains dry and free of the need for expensive refurbishment.

OWNER RESPONSIBILITIES: BUDGET APPROPRIATELY

Less than half of 1% of a typical stadium construction budget is spent on expansion joints. However, a majority of post-tenancy problems with these structures relates to water ingress. Owners must be receptive to the recommendations for superior technologies presented to them by designers and be prepared to allocate additional resources to the design contract to allow proper detailing of joints and their relationships to other structural elements. By spending slightly more of the construction budget on waterproofing, stadium owners can expect, and indeed demand, trouble-free, dry and lasting joint seals.

DESIGNER RESPONSIBILITIES: DESIGN FOR JOINT SEALING TECHNOLOGIES FROM THE BEGINNING

Even the best waterproofing system is going to fail if there are holes in the membrane. Structural expansion joints represent a planned hole in the waterproofing membrane. It is wise to begin with consideration of how these major holes will be addressed and work with the membrane materials out from there.

Designing out expansion joint problems begins with consideration of the following:

ACKNOWLEDGE THE NEED FOR EXPANSION JOINTS:

Structural materials have limitations. Extreme weather conditions can cause damage over time. Cracks as a result of overstressed materials are nearly impossible to seal and can result in dangerous structural weaknesses. Properly designed expansion joints will prevent cracking, while carefully chosed sealant systems will withstand weather conditions and keep the facility dry.

CHOOSE EXPANSION JOINT LOCATION CAREFULLY:

Away from corners -- Corners are a bad place for expansion joints. Do not cast, or use the joints between precast corner units as the place for the structural expansion joints. Corners are impossible to set while creating a consistent expansion joint gap size. Furthermore, the angles created in the corner make awkward geometries for the attachement of sealant systems. Instead, cast the corners solid, or weld these precast connections and make them non-moving. Make the structural expansion joint in a single line just off the corners.

Not through planters -- Never try to waterproof structural expansion joints inside planters. If the joint runs through areas where planters are designed, detail the planters with back-to-back walls, leaving the expansion joint sealable.

Away from obvious water sources -- Keep scruppers away from joints and don't slope drainage across joints. Instead, for example, locate joints at the top of a ramp. Do not expect a deck to drain down a ramp and over, under or through the joint.

Think about interiors -- Joints cut completely through the whole structure. Therefore, think about the interior layouts in relation to expansion joints. Considered early enough, it is even possible to hide some joints between back-to-back interior walls thereby eliminating their aesthetic impact, as well as the need to bridge them. Make sure the interior subcontractors know where joints are, and the effect the joints may have on location of mechanical or plumbing fixtures. Finally, select and specify all-metal, high-point-load expansion joints capable of handling small-wheeled catering, cleaning and other traffic that typically destroys "rubber and rail" joint systems.

SELECT STRUCTURAL SUPPORTS WISELY:

Choose split columns rather than single columns with slide bearing pads. A single-column structure results in hard-to-seal conditions around the column caps that create shear conditions for which most watertight joint systems are not designed. Split columns ensure that a system's sealing integrity can be maintained.

SIZE JOINTS PROPERLY:

There are four main facets related to sizing joints properly - expected movement, functional and installation temperature range, tolerance build-up, and movement capability. Architectural teams must also take the lead for sizing in joint design. Often, the structural team will make recommendations without considering a material and its movement capability and other effects on joint design. This can be avoided if the architectural team selects a technology and takes it to the structural team with the question: "What size joint do we need if we seal the joint with THIS specific technology?" The resulting joint size calculation can then take into account the movement capability if the product or technology type to be used.

TAKE TIME TO FIND THE RIGHT TECHNOLOGY:

Limit specifications to manufacturers that continually demonstrate a commitment to joint treatment, have sound technology, the ability to ensure and guarantee watertightness in plane and direction changes, and a commitment to quality. A trend in the specialty products industry is the tendency of suppliers to commoditize products, thereby removing much of the value essential to proper performance. The ability and willingness of manufacturers to offer solutions and to fabricate watertight transitions in plane and direction, such as up and down treads and risers, remain rare differentiators.

Features in purpose-designed joint systems include integral heat-weldable, thermoplastic rubber flashing sheets for "sandwiching" into deck waterproofing materials on split-slab decks. This ensures total water-tightness over occupied space below, while heavy-duty aluminum or steel side rails and stainless steel retaining capping strips allow long-term maintenance access to the sealing insert which in turn is designed to handle cyclical movements.

THINK AND DESIGN IN 3-D:

Develop isometric, line-sketch schematics to show all the joints throughout the stadium. Include all changes in plane, direction, and intersection with other materials. This will put the design team on the same page, allowing all participants to identify and design out many problems before construction begins. Cross-reference the material selection for each joint in the schematic with a cross-section detail. In addition, show axonometric details of each transition in plane and direction, especially when illustrating transitions between different material technologies, e.g. between a concourse deck joint and a wall joint. Manufacturers publish on their Web sites most of the axonometric details needed to detail and specify watertight transitions within the same product, as well as between different technologies. This makes detailing these conditions as simple as cutting and pasting.

COMMUNICATE JOINT LOCATIONS TO ALL INVOLVED:

Make sure to show expansion joints on all drawings, including structural, architectural, mechanical and landscape. In the specifications, include a specific reference for responsibility of all trades to appropriate treatment of their work at expansion joints.

WRITE PROJECT-SPECIFIC SPECIFICATIONS:

Stadiums are not the place to use a "cookie-cutter" approach to expansion joint design. The specifications for each job must match the specific performance demands of each venue. Research available technologies, implement them into the design and write specifications that reflect the choice. Make sure to stick with the plan throughout the project to ensure technology continuity and continuity of seal.

HAVE COURAGE:

Joint systems are a tiny percentage of the stadium construction jobs. Having engaged in the aforementioned expansion joint design-emphasis process, designers should have the courage to defend proprietary specifications of superior joint system, and hold to them even under pressure for substitutions of cheaper, less-effective alternatives.

CONTRACT EXECUTION: GENERAL CONTRACTOR, OWNER RESPONSIBILITIES LIMIT WORK TO CAREFULLY SELECTED CONTRACTORS

Limiting work to a select group of contractors, often those recommended by the expansion joint system manufacturer, can be a huge factor in ensuring watertight joint seals. These contractors have been properly trained to install the chosen systems and can address substrate conditions that help ensure watertightness. Because they work closely with manufacturers, these contractors are not likely to underbid the job, keeping change-order cost increases to a minimum, and are likely to be versed in, and willing to remain committed to, a communication process involving the designer, owner representative, manufacturer and general contractor.

COMMUNICATE CLEARLY AND OFTEN:

Hold a pre-construction meeting with all parties involved in the treatment of work at and around expansion joints. This meeting should take place prior to pouring concrete that will define the expansion joints. Make sure all superintendents and forepersons with responsibility for casting activities attend the meeting to review such issues as:

Forming joint-gaps in relation to temperature changes
Ensuring solid form construction to prevent collapsed and misaligned joint forming
Proper consolidation and through vibration, of slab edges and blockouts
Zero tolerance on blockout formation
Finesse concrete work for final blockout preparation
Location, elevation and configuration of joint curbs
Execution of concrete work to handle transitions to vertical plane
Protection of joints and traffic routing until decks are opened to normal use

EMPHASIZE EXPANSION JOINTS DURING ALL CONSTRUCTION PHASES:

Continue to place expansion joints on meeting agendas throughout the construction process. Many subcontractors, including electrical, HVAC, masonry, flooring façade panel, waterproofing and caulking, work in close proximity to expansion joint locations and they must be aware their work cannot impede structural movement that will occur at expansion joints or compromise the achievement of watertightness at expansion joints in any way. As the construction progresses, the general contractor must emphasize expansion joints during each stage. Expansion joints must be considered a critical path item, rather than an added piece at the end of the project. Failure to emphasize expansion joints during construction is a significant contributor to delays, cost overruns and the reworking that characterizes preparation of joints to receive the expansion joint system.

IN CONCLUSION:

Sky boxes that won't heat or cool; damage to high-dollar corporate boxes; lost concession-vendor revenue; and icy slip hazards are among the numerous complaints stadium owners and managers have endured as a result of leaking expansion joints. Furthermore, most retrofit expansion joint contracts far exceed the cost of doing it right the first time. Yes, stadium construction is a complex process. Nevertheless, with notable new construction successes, including Phillies Ballpark and Keyspan Park, and numerous retrofit successes, including FedEx Field, Fenway Park and American Airlines Arena, have demonstrated that a new paradigm for expansion joint treatment is not only possible but also practical.

Lester Hensley is President and CEO of EMSEAL Joint Systems Ltd. Having first joined the company in 1990, Hensley is credited with using EMSEAL's base product offering as a springboard for market-driven product innovation and for securing a solid reputation among architects, engineers, contractors and distributors, as well as the company's network of independent manufacturers' representatives.

15-Jun-06 10:00 AM