Sourcing Wall or Roof Thimbles for Engine Exhaust Piping Applications

Exhaust thimble installation shown on a non-combustible wall application

Exhaust pipe thimbles are used where engine exhaust pipes penetrate through walls or roofs. The thimble provides an air gap between the hot exhaust pipe and the building structure. When exhaust pipes penetrate through combustible walls or roofs, thimbles are required by NFPA 37. Thimbles can be furnished with thermal insulation, designed to accommodate roof pitch, and may be constructed in various grades of stainless steel. offers NFPA-compliant wall and roof thimbles for engine exhaust piping applications. When sourcing an exhaust thimble, please gather the following data and contact us for a proposal.

  • Thimble application: is it for a wall or roof installation?
  • If for a roof application, is the roof pitched? If so, what is the roof pitch?
  • Is the wall or roof structure considered to be combustible, or non-combustible material?
  • What is the thickness of the wall or roof? For example, standard concrete block walls are 6″ thick.
  • What is the diameter (outside diameter) of the exhaust pipe?
  • What is the required construction material for the exhaust thimble? Stainless steel is recommended for a longer life and better building aesthetics.

With this information on hand, please submit a request for proposal here:







    Project Name:

    Exhaust Pipe Diameter (OD in inches):

    Roof or Wall Thickness (if not specified 6" thickness is assumed):


    For Roof Applications:

    *if applicable, specify roof pitch under Comments area below.

    Thimble Construction Material:

    Additional specifications or comments:

    Would you like to include supporting documents or drawings that would assist us in processing your request (6MB limit, PDF, JPG or TIFF files only):

    Our proposal will include a drawing for your review and approval prior to fabrication. We look forward to supporting your requirements!