30Step 9. FinishingFigure 33 shows the minimum vertical and correspondingmaximum horizontal dimensions of fireplace mantels or othercombustible projections above the top front edge of thefireplace. See Figures 3 and 4 for other fireplace clearances.Only non-combustible materials may be used to cover theblack fireplace front.WARNING: WHEN FINISHING THE FIREPLACE,NEVER OBSTRUCT OR MODIFY THE AIR IN-LET/OUTLET GRILLES IN ANY MANNER.!Figure 33.Minimum Vertical and Maximum HorizontalDimensions of Combustibles above FireplaceCAUTION: IF JOINTS BETWEEN THE FINISHED WALLSAND THE FIREPLACE SURROUND (TOP AND SIDES)ARE SEALED, A 300° F. MINIMUM SEALANT MATE-RIAL MUST BE USED. THESE JOINTS ARE NOT RE-QUIRED TO BE SEALED. ONLY NON-COMBUSTIBLEMATERIAL (USING 300° F. MINIMUM ADHESIVE, IFNEEDED) CAN BE APPLIED AS FACING TO THE FIRE-PLACE SURROUND. SEE THE DIAGRAM BELOW.NOTE: Sheetrock or other combustible material such aswood can be placed on the top edge of the fireplace. A 1/2-inch gap along the side must be maintained.Hearth ExtensionsA hearth extension may be desirable for aesthetic reasons.However, ANSI or CAN/CGA testing standards do not requirehearth extensions for gas fireplace appliances.Figure 34. Sealant MaterialTOP EDGE OF FIREPLACE1/2"12"CEILING31”NOTE: SHEETROCK OR WOOD CAN BE PLACED ONTHE TOP EDGE OF THE FIREPLACE. A 1/2-INCH GAPALONG THE SIDE MUST BE MAINTAINED.TOP EDGESIDE EDGE1/2” GAPTOP EDGESIDE EDGE1/2” GAPQV-STQV-PIER