In accordance with FBC 2020 (7th Edition),
the following clearance below raised roof mounted mechanical units applies inside & outside the HVHZ*:
|WIDTH** OF MECHANICAL UNIT||MINIMUM CLEARANCE ABOVE SURFACES|
|FBC 1510.10||FBC 1522.3|
|Outside HVHZ||Inside HVHZ||Height|
|< 24″||< 24″||14″|
|24″ < 36″||25″ < 36″||18″|
|36″ < 48″||37″ < 48″||24″|
|48″ < 60″||49″ < 60″||30″|
|> 60″||61″ & Wider||48″|
Important to note that in the 2015 and 2018 International Building Code, Sections 1510 and 1522 do not exist, lending the assumption that there is no roof clearance requirement in the code. We recommend using best judgement or this guide as a basis for your decision considering the rooftop maintenance requirements & other factors (vibration, noise, etc).
Also, the use of ‘sleepers’ shall not be permitted in the Florida HVHZ* zone.
* NOTE: HVHZ is defined only as Broward and Dade Counties, FL.
** While ‘width’ is not defined in either section, it is assumed by this firm to indicate the shortest horizontal dimension vs depth & supports multiple unit installation intention without raising the clearance. Width is considered our ‘depth’ in our examples and calculators.
The Authority Having Jurisdiction (AHJ) has leeway to permit lesser clearance heights than the listed table values. Always refer to the AHJ for the final determination on what minimum clearance height is required.
NON-HVHZ (FBC 1510.10) & HVHZ (FBC 1522.3.3) Exceptions: In buildings where the existing rooftop equipment, in the opinion of the building official, provides sufficient clearance to repair, recover, replace and/or maintain the roofing system or any of its components, such existing equipment need not comply with Table 1510.10.
Non-HVHZ (FBC 1510.10) Only Exception: Roof mounted mechanical units shall be mounted on curbs raised a minimum of 8 inches (203 mm) above the roof surface, or where roofing materials extend beneath the unit, on raised equipment supports providing a minimum clearance height in accordance with Table 1510.10. (For HVHZ, no such provision exists, so this firm interprets this as curbs shall comply with Table 1522.3 unless noted otherwise (U.N.O.) by the AHJ.
Last Update: April 6, 2021