Party Walls

The 2010 ADA Standards and the A117.1 Standard for Accessible and Usable Buildings and Facilities require the bottom 10 inches on the push side of a door to be smooth and free from any obstructions for the full width of the door. While there are some exceptions (e.g., sliding doors or tempered glass doors without stiles), this requirement applies at the following locations:

• 2010 ADA Standards:
  • Public and Common Use Areas: All doors along the accessible route
  • Accessible Dwelling Units: The primary entry door and all doors within the unit intended for user passage
• A117.1 Standard:
  • Public and Common Use Areas: All doors along the accessible route
  • Type B Dwelling Units: The primary entry door
  • Type A and Accessible Dwelling Units: The primary entry door and all doors within the unit intended for user passage

The door surface provision is intended to ensure the safety of people with disabilities who require the use of a wheelchair, walker, cane, or other mobility aid. It is common to utilize the toe of the wheelchair or leading edge of another mobility device to push open a door while moving through it. The smooth surface allows the footrest of a wheelchair or other mobility device that comes into contact with the door to slide across the door easily without catching.

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When designing accessible parking spaces, it is important to remember that the slope of the ground surface for the entire parking space and adjacent access aisle must not exceed 2% in any direction. We frequently see noncompliant slopes at accessible spaces, especially when the ground surface is asphalt or permeable pavers.  The slope along the perimeter of spaces at curbs or gutters is frequently more than 2% at up to 5%, which requires careful detailing and planning on the part of the architect, civil engineer, and on site contractors to ensure that a compliant slope is achieved at the accessible parking spaces. At parking structures and precast garage systems, we have found that important details and coordination needed to achieve compliant ground surface slopes are often overlooked.

 

In parking structures, it is common for an area along the perimeter of the slab (adjacent to walls or parapets) to slope in excess of 2% for drainage purposes. In some cases, this slope is embedded into the precast system. As a result, accessible parking spaces must be located away from the sloped edges during the initial design phase.

In other cases, noncompliance results from the application of a cast in place (CIP) wash applied to the top of the precast slab. In the detail shown below, note the slope condition at the CIP topping. The wash is often indicated only in section details on the precast drawing set, making it easy to miss if designers are not specifically looking for how these details affect accessible parking spaces. The entire project team involved in the design and/or construction of the garage must be made aware of where accessible parking spaces are located and understand the specific slope requirements to ensure that details are properly coordinated.

Once the garage is constructed, it is nearly impossible and very costly to fix noncompliant slopes at the head of accessible parking spaces. In some garages, we have been able to solve the problem by shifting the striping at accessible parking spaces. This results in the steeply sloped ground surface being located fully outside of the parking space and access aisle. The problem is that this solution is dependent upon whether the spaces can be shifted without compromising the minimum required width of the drive aisle or obstructing access to other parking spaces.

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By Kai Starn, Sustainability Consultant

Autumn has arrived again in the Northeast and the foliage is in full splendor. Over the Canadian Thanksgiving / Columbus Day weekend, I headed up to Ontario to deliver one final truckload of building materials to my family’s property there, which is located an hour and a half across the Canadian border. While I am a Connecticut native, the land bordering the Frontenac Provincial Park has been in my family for generations. In the 1980’s, my grandfather logged the area, and subsequently built a road and a log cabin on the property, which is where my grandmother now spends time during the summer.

The main cottage is a gathering place for family reunions; as such, I had always envisioned building a small weekend cabin to accommodate extra people for the occasions when there was sure to be a full house. About a year ago, I began to design and build this structure. When completed, the tiny cabin will be a simple, un-insulated cottage of old. But, dang, if it doesn’t scream summer and lake and relaxation!

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As a resident of Washington, D.C. for nearly ten years, I’ve spent a fair amount of time frequenting the city’s burgeoning restaurant scene. Much like my fellow Accessibility Consultants at SWA, even when we’re off the clock, we notice structural violations of federal accessibility laws on a daily basis. I would love to say that DC’s restaurant industry is an exception, but unfortunately there are still many challenges facing diners with disabilities in Washington.

Accessibility regulations that apply to restaurants are outlined under Title III of the Americans with Disabilities Act (ADA). Achieving compliance with the ADA can be a substantial task, but not without significant benefit. Recent statistics show that people with disabilities spend over $35 billion in restaurants a year. This is no small change for an industry with ever-increasing competition. Compliance also mitigates risk of litigation, which is particularly important as the U.S. Department of Justice and advocacy groups continue systemic investigations across the country.

Following are a few general rules of thumb to remember when providing equal access to guests with disabilities:

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BACKGROUND

The multifamily building industry has adopted a best practice long touted by the building science community: continuous insulation at the exterior of the building. However, even in this ideal circumstance in which the insulation is installed flush and without gaps against the exterior substrate (concrete block or sheathing) with an air barrier applied to this substrate beforehand, the overall performance of the insulation will be vastly reduced by the installation of shelf angles.

Shelf angles (also know as relieving angles) are designed to support the expansion and contraction of the brick coursing; however, this presents a direct challenge to the continuity of exterior insulation. Standard design details interrupt the exterior insulation at every shelf angle, typically at every floor in line with window lintels. Since the shelf angle is made of steel, a highly conductive material, this interruption impacts not only the effectiveness of the insulation in general, it provides a considerable thermal bridge over the entire horizontal band of the building at every occurrence.

A recent article by Urban Green Council, “State Energy Code Clarification Will Stem Heat Loss through Walls,” made it clear that a continuous shelf angle has “about the same poor thermal performance as [an] exposed slab edge.” The full article can be read here.

 

SWA RECOMMENDATION #1: LIMITING SHELF ANGLES

Not all buildings require relieving angles. Building owners, architects, and structural engineers should first ask themselves whether relieving angles are necessary at all for the building being designed. If it is determined that these angles will be necessary, the next question the structural engineer should ask himself is what the minimum frequency necessary is to support the brick course. Generally speaking, buildings do not need one shelf angle per floor—despite this being common practice.

In addition to the aforementioned energy implications involved in specifying shelf angles, there are other benefits to eliminating these steel members when possible. The most obvious impact is on upfront costs. At approximately $25/foot of angle iron (via Union Iron Works), shelf angles for multifamily buildings in New York City can cost tens of thousands of dollars.

Upfront and operating (i.e. energy) costs aside, there is also the embodied energy of the material to consider. Not only does the manufacture of the steel angle contribute to its embodied energy, but also all of the energy used to transport these pieces to the project site. By reducing the need for the production of these angles, the overall energy expended to construct a new building decreases.

One additional consideration for owners is the maintenance required for shelf angles. The introduction of brick lintels creates an inherent and inevitable need for future maintenance. Since the cost of this upkeep is often considerable, owners may wish to use the opportunity to limit shelf angles during design to reduce long-term maintenance costs.

 

SWA RECOMMENDATION #2: OFFSETTING SHELF ANGLES

In addition to limiting their frequency, consider a shelf angle offset to further reduce thermal bridging. One such system that allows for this is manufactured by FERO called FAST (FERO Angle Support Technology).

FAST is designed to offset the shelf angle from the structural backing, allowing the insulation and air barrier installations to be more continuous. More information about this product can be found on their website.

SWA welcomes the input of design teams for other possible solutions to achieve a more continuously insulated wall. By accomplishing this, the building will have a truly continuous thermal envelope. As a result, thermal bridging will be eliminated along with the associated energy losses.

 

 

CONCLUSION

To implement best building practices, fulfill the continuous insulation requirements of certification programs, and comply with NYC Energy Conservation and Construction Code, SWA recommends limiting the number of shelf angles in the construction of the envelope. This will help limit upfront material and long-term maintenance costs.

SWA also recommends off-setting the shelf angle to reduce the thermal bridging these steel elements create. Fewer shelf angles means that there are less obstacles imposed on exterior insulation, resulting in less thermal bridging. Limiting the impact of shelf angles produces a more robust and insulated envelope that will, in turn, positively impact the energy performance of the building and comfort of its occupants.

SWA would like to thank Robert Murray for his assistance with this article.

Robert J. Murray, P.E., LEED AP, Principal
Murray Engineering, PC
307 Seventh Avenue, Suite 1001
New York, NY 10001
Telephone: 212.741.1102
Email: rmurray@murray-engineering.com

 

REFERENCES

1. Anderson, J., D’Aloisio, J. DeLong, D., Miller-Johnson, R., Oberdorf, K., Ranieri, R., Stine, T., and Weisenberger, G. “Thermal Bridging Solutions: Minimizing Structural Steel’s Impact on Building Envelope Energy Transfer.” American Institute of Steel Construction. Modern Steel Construction, 1 Mar. 2012. Web. <http://msc.aisc.org/globalassets/modern-steel/archives/2012/03/2012v03_thermal_bridging.pdf>.

2. FERO: Engineered Construction Technologies. Product Catalogue. Edmonton: FERO: Engineered Construction Technologies, 2014. Web. <http://www.ferocorp.com/pages/fast/fast.html>