45-Degree Firestop Spacer for 4-Inch Chimney Installations

This 45-degree firestop spacer is an angled trim and spacing accessory for certain 4-inch insulated-chimney layouts where the chimney passes through a compatible opening at an angle. It is intended to help finish the penetration while keeping the chimney separated from surrounding construction as required by the approved installation plan.

Because angled wall and ceiling penetrations vary significantly by structure, this part should not be treated as a universal wall thimble or as approval to route a chimney through any wall, RV, shed, yurt, or other structure.

When an Angled Firestop Spacer May Be Used

An angled spacer can be useful when a permitted chimney route requires a 45-degree penetration and the appliance, chimney system, structure, and local authority all allow that configuration. The opening, shielding, support, and clearances must still follow the requirements for the complete chimney system.

Do not base the penetration size or wall construction on a generic rule. Combustible framing, insulation, wiring, roofing, siding, and interior finishes can all change what components are required.

Use Insulated Chimney at Building Penetrations

Where a chimney passes through a wall, ceiling, or other building assembly, use the listed insulated chimney and the penetration components required by the chimney manufacturer's instructions. Single-wall connector stovepipe should not be substituted for insulated chimney at a building penetration.

Related 4-inch chimney components include:

• 4-Inch Insulated Chimney Pipe - 36-Inch Length
• 4-Inch Insulated Chimney Pipe - 24-Inch Length
• 4-Inch Selkirk HT Firestop Spacer
• 4-Inch Wall Radiation Shield

Plan the Chimney Route Before Ordering

Read our 4-Inch Stove Pipe Guide and review the appliance and chimney-system manuals before selecting penetration parts. If your layout requires an offset, make sure the elbows, supports, chimney lengths, and penetration protection all work together as one approved system.

For Selkirk Ultra-Temp installation resources and current technical documents, see the Selkirk Ultra-Temp resource page.

Installation and Safety

Do not cut a penetration or modify a wall based solely on this product page. Confirm the final layout, opening size, required airspace, shielding, structural support, weather sealing, and firestop method against the appliance manual, chimney manufacturer instructions, and the local authority having jurisdiction.

If you are unsure whether this angled spacer is appropriate for your project, contact us with details about the appliance, chimney route, wall or roof construction, and planned angle before ordering.