By: Jose Santos
July 28, 2020
The building codes mandated by the New York City (NYC) Department of Buildings are perpetually evolving. Under the current code, parapet walls at main roofs must maintain a minimum height of 42” above the finished roof membrane system or pedestrian surface. The most common parapet wall construction in the city is brick masonry. Code compliant buildings from 70-100 years are subject to updates when there is a requirement for replacement. For the purposes of this article we will specifically focus on buildings that are required to have cyclical inspections under the Façade Inspection and Safety Program (FISP; formerly Local Law 11/98); there are universal principles that can be applied to other parapet wall construction as well.
In order to maintain code compliance and prevent violations and penalty fines, the building Owner must address this issue before the next (FISP; LL 11/98) cycle. As discussed in our article Parapet Wall Height, Requirements & Recommendations, there are only a handful of solutions to remediate inadequate parapet height and fall protection:
Installing a mounted railing system or installing additional courses of brick to the existing parapet wall are two common solutions. If neither of these options are viable, a full parapet replacement may be required.
If installing a side-mounted railing is considered to meet, this method requires consulting with a qualified Engineer/Architect. An Engineer/Architect must review the conditions of the existing parapet wall to ensure that it can withstand the extra weight and additional wind load pressures. The base, width, and overall size of an existing parapet are constructed to withstand a calculated amount of wind-induced stress, so increasing the stress placed on the parapet can lead to potential failure if improperly performed.
During the review and design process of a railing system attachment and/or additional masonry, a pull test should be performed to evaluate the strength of the parapet wall. The pull test on a masonry wall typically consists of a configuration that would prove the wall can withstand a force of at least 200 pounds per square foot. Once the dimensions and strength of the parapet are confirmed, an Engineer will determine the railing composition and attachment to meet the load requirements. A contiguous mounted railing system can be installed in one elevation and split at each return or corner.
Another way that brick parapet walls may be upgraded to comply with the NYC DOB parapet height requirements, is by adding courses of brick or other approved materials atop the existing structure. Much like the mounted railings, an Engineer must evaluate the parapet wall to verify that it is structurally sound and that additional courses of brick can be supported and properly anchored into the existing wall. Structural reinforcement is required.
Unfortunately, parapet wall repair is not always a viable option for a building, and a full parapet replacement is required. If a parapet has failure due to deterioration of its components, including shifting masonry, vertical and horizontal cracks and other related structural failures, then selective restoration may not be an option.
The new parapet wall must not only meet the 42” height requirement, but also account for the new energy code that was implemented on May 12, 2020 for roof systems; this new R-value is R-33, which is an increase in insulation thickness. Options to comply with the building code requirement outside of adding additional insulation to the top surface of the roof deck are quite limited, but proper insulation and code compliance ensure the building is energy efficient and cost effective for the Building Owner. The increase in insulation thickness does impact the height of the existing parapet, and is likely to require modifications to meet code.
Typically, mounted railing installation is less expensive than parapet wall replacement. Although the options to make a parapet wall code compliant are limited, there are a number of associated variables to consider. Parapets are only one of the commonly addressed component parts of restoration efforts on aging buildings. A professional building envelope consultant is well suited to assist a building owner with the evaluation of a parapet wall; they can help determine whether a restoration effort or parapet replacement is required and incorporate best industry practices in a capital improvement plan.