2.THIMBLE: An approved thimble must be used when the connection from the stove is made through a combustible wall to a masonry chimney. There are several methods you can use for connection through a combustible wall, two of which are illustrated in this manual. For additional methods, consult local building authorities or use the standards set forth in NFPA 211.
Also, listed prefabricated metal thimbles are available for use with wood stoves. The manufacturer’s installation for the thimbles must be strictly followed to assure the safety of the system. Be sure to maintain the designated clearances to combustible materials.
A. BRICK CHIMNEY THIMBLE ASSEMBLY: Construction of the brick thimble assembly requires 12” (305mm) of brick around a fire clay liner. Be sure the point of penetration allows an 18” (457mm) clearance from the connector to the ceiling. For a 6” (152mm) chimney connector, an opening of 30” (762mm) must be cut in the wall to maintain the required 12” (305mm) of brick separation from combustibles. It will be necessary to cut wall studs and install a header and sill frame to maintain proper dimensions and to hold the weight of the brick (Figure 8).
FIGURE 8
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