Inspecting Monopole Structures
A monopole is a single pole structure that supports or is capable of supporting a sign. A monopole may reach 50 feet to 120 feet in height but may be higher or lower, and is bolted to or embedded in a concrete foundation sufficiently sized to resist the code required imposed loads of the structure. The top of the monopole may be comprised of a circular steel tube or arm affixed to the top of the vertical steel pole horizontally or it may be partially of fully cantilevered on one side only.
A monopole includes secondary steel beams, channels, angles, or similar components mounted upon the horizontal steel arm. The secondary steel beams, channels, and angles form a framework, or armature, upon which vertical panels are affixed. The foundation, vertical pole, horizontal arm, steel frame, and vertical panels are all parts of the permanent monopole installation.
The signage displayed on a monopole, which may include fabric, paper, or illuminated LED panels, is typically mounted to the vertical steel frames and may be replaced routinely. Monopoles are sometimes altered for telecommunication, utility, security, or similar use.
B. Applicable Codes
Monopole structures designed, filed, permitted, and constructed pursuant to the 2008 NYC Construction Codes shall be subject to the requirements of such codes. Monopole structures designed, filed, permitted, and constructed pursuant to the 1968 Code or with laws in effect prior to the effective date of the 1968 Code shall be subject to the requirements of the 1968 Code and 2008 NYC Construction Codes as specified in section AC 28-101.4.
The installation of any monopole structure on a building or on ground shall be engineered by a registered design professional, and the design shall take the following into account:
- Codes. The installation of the monopole shall be in accordance with all applicable laws and regulations
- The foundation and free-standing monopole structure shall be engineered and the foundation subgrade and or piles used to support the monopole shall be designed in accordance with BC Chapter 18.
- The installation design shall be in accordance with the manufacturer’s recommendations.
- The monopole structure shall be filed and constructed in compliance with the NYC Zoning Resolution, including height requirements.
- The products shall be installed to conform to the design criteria as set for the in the 1968 Administrative Code of New York, and Chapters 16, 19, 20, and 22 of the 2008 NYC Building Code.
D. Construction Documents and Permits
The monopole structure installation shall be filed with the Department as an Alteration Type 2 or 3 application and shall require associated electrical and signage filings and permits. The application shall include, at a minimum:
- Site Plan. The site plan shall identify buildings and other physical features in relation to the property boundaries. It must identify existing buildings, structures, and features on the property, including a general overview of the project’s proposed changes to the property.
- Architectural drawings. The architectural drawings shall include the floor plan, elevation(s), section(s), construction details, structural drawings and/or other drawings sufficient to show and describe the monopole system elements, their arrangement and operation. Structural drawings shall show all the foundation elements and/or anchorage details of the monopole assembly and related equipment.
For detail requirements for drawings submission, refer to the Department’s Plan Examination Guidelines
Where a monopole structure designed to support a sign is to be altered for telecommunication, utility, security use, such monopole structure shall be filed with the Department as an Alteration Type 2 application and shall require associated electrical filings and permits. Monopoles supporting cellular antennas and related equipment shall be subject to applicable provisions of the Code, including but not limited to BC Chapters 15 and 16 of the 2008 NYC Building Code, and the New York City Zoning Resolution.
E. Special Inspections
The installation of signs and sign structures shall be subject to the requirements of BC Chapter 17 of the 2008 NYC Building Code for special inspection for the materials and methods of construction employed. Required special inspections shall be indicated on the construction documents, and on forms filed with the Department.
F. Annual Inspection
In accordance with section BC H105.2 of the 2008 NYC Building Code (formerly AC 27-508 (b)), signs and sign structures are required to be inspected annually. Such annual inspection should include visual inspection, and engineering and materials testing evaluations of all the components of the monopole structure and foundation. Such inspection records should be maintained and should be made available for review by the Department upon request.
The inspections and evaluations should be conducted by a New York State licensed professional engineer. The inspections and evaluations should include, at a minimum, the following:
- Visual inspection of welds, anchor rods, bolted connections, and materials for structural fatigue and metal corrosion, including corrosion related to salt, fog, or other environmental conditions. Visual inspection of welds and bolts, in particular anchor bolts, should be accompanied by physical sounding, ultrasonic tests, X-rays, porosity, etc. to detect any fractures, fatigue, or defects in the concealed portions of the anchorage.
- Close-up, hands-on visual and laboratory inspection of structural steel posts, horizontal arms, and all armatures supporting signage panels, etc. to ensure continued stability of connection systems, and well-maintained site conditions.
- Conformance between the field conditions at the time of inspection and testing, to those conditions noted on the Department approved and permitted construction documents.
- Other evaluations: In addition to the recommended inspections and testing by a professional engineer, the following evaluations are also recommended to be performed by a professional engineer:
- General wear and tear
- Log of repairs, adjustments, replacements, and maintenance
- Report of peak wind speeds encountered, and dates of wind speeds exceeding 110% of those permitted for the location by the 2008 New York City Construction Codes
- Other inspections as the manufacturer may recommend.
In the event that the owner and/or engineer, during the performance of their evaluation, identifies a defect in the monopole structure, including but not limited to:
- bolted base connections that have been embedded or buried in concrete or soil
- fractured anchor rods
- failed welds
- vertical pole out of alignment
- loose signage panels
In accordance with section AC 28-301.1, the owner and the engineer are required to immediately notify the Department of an unsafe condition by calling 311 and by written notification to the Department. The owner shall be responsible at all times to maintain the monopole structure in a safe and Code-compliant manner.
G. Department Requests for Reports
The Department has authority to require tests as evidence of compliance with the Codes in accordance with recognized test standards at no expense to the City. A response to a Department order shall provide site-specific criteria for material and engineering evaluations for the size, location, and installation of a monopole structure.