Connection Types Wiki · Gas, venting & HVAC

Chimney Storm-Collar Clamp

A circular inner opening formed by wrapping a conical sheet-metal storm collar around an outer chimney pipe or flue, clamped shut and sealed against weather.

Illustration of a Chimney Storm-Collar Clamp
Gender
female
Connects by
clamp, friction, adhesive
Standards
UL 103; UL 103HT
Regions
North America, worldwide

How it connects

Wraps tightly around the chimney pipe outer casing via a clamping band, tab/slot, or bolt tab, sealed with non-hardening waterproof silicone or mastic along the top lip.

Male and female halves

Female opening formed by the collar ring encircling the male outer cylinder of the chimney pipe.

Usually connects to

  • chimney outer casing
  • insulated chimney pipe outer wall
  • vent pipe male surface

Common sizes

  • 6 in to 14 in inner opening diameter (typically matching standard 6, 7, 8 in inner diameter double/triple-wall chimney pipes with 8 to 12 in outer diameters)

Where it is used

residential chimney ventingwood stove and fireplace chimney flashingHVAC and exhaust roof penetrations

Variations

  • worm-drive hose clamp closure
  • tab and slot interlock
  • welded flange bolt closure

How to recognise it

Recognizable as a frustoconical sheet metal umbrella wrapped around a cylindrical flue with a circular top rim sealed with silicone, held closed by an integral clamp or fastener.

Often confused with

Confused withHow to tell them apart
roof flashing coneThe roof flashing cone penetrates and mounts to the roof deck, whereas the storm collar mounts directly onto the pipe just above the cone to divert runoff.
locking bandA locking band joins two stacked chimney pipe sections mechanically; a storm collar only provides weather counter-flashing.

Also called

chimney storm collar femalesplit storm collar interfacewraparound storm collar ID

Good to know

The collar is split so it can be installed or retrofitted around an existing flue pipe rather than slid all the way down from the pipe terminus.

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