How much clearance (height in inches) does your roof curb and collar need? The answer depends on the climate your home or building is in.
Roof curbs are only intended for low slope or flat roofs. For a roof pitch 2/12 Pitch or lower, refer to the chart under the map below.
You can use taller roof curbs and collars for additional clearance in warmer climate zones, but you can't use shorter ones in colder zones.