Offset Block for Masonry Fireplaces

Offset Blocks

Use FireRock Offset Blocks when design paramerers do not allow for a vertical chimney installation. Offset Blocks allow you to move the chimney path so that objects, such as another fireplace, may be positioned above the firebox.

A non-combustible column under every fifth block must support the Offset Blocks in a series. Offset blocks are stacked in series with each one providing a maximum offset 2 5/8″. Offset direction may be left, right, back, or in a spiral pattern for “twisting” flues.

  • Offset Block Height:4"
  • Additional Measurements: 24" (W) x 28" (L)
  • Maximum Horizontal Distance (or max offset): 40"
  • Clearances: 1" clearance to combustibles
  • Each block has an angled flue hole that provides a 30 degree vertical passageway for flue gases
  • Good for moving the chimney outside the wall of the home to avoid interference with the upstairs floor plan


Important: Please consult local building codes for specifics regarding all masonry fireplace applications.

Masonry Fireplace Accessories - Offset Blocks

Click to View Other Masonry Fireplace Accessories:

Installation Kits  |  Firebrick & Mortar  |  Outside Air Kit  |   Solid Chimney Block   |  Chimney Pots

Metal Chimney System   |   Bricking Flange  |   Height Extension Kit

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