When building a fireplace mantel, you need to ensure the proper fit for your mantel surround and your fireplace mantel shelf. To build your fireplace mantel/fireplace mantel shelf, use the following guidelines to measure your fireplace.

Our fireplace mantel kits are designed to surround your facing material (brick, tile, etc.). You will notice that we allow our fireplace mantels to overlap your facing material in three areas. 1) Mantel Opening Height, 2) Mantel Opening Width, and Mantel Return Depth. In most cases this overlap should be a minimum of 1/2". To build your fireplace mantel, you should start by determining if a standard size mantel surround will work, if not provide us with the B,C and G dimensions from below for a custom size.


The key B, C and G dimensions influence A, D, and E. All other dimensions are fixed depending upon the style of the fireplace mantel kits. See standard dimensions. Note: Exceptions can be made (i.e. - Reduce leg width (X) or reduce breast height (Z). Call 888-493-8898 for details.
Mantel Dimension Diagram
A - Overall Height
B = Opening Height
C = Opening Width
D = Overall Fireplace Mantel Shelf Length
E = Body Width
F = Fireplace Mantel Shelf Depth
G = Return Depth (Cavity Behind Mantel)
X = Leg Width
Y = Leg & Shelf Overhand
Z = Breast Height
Mantel Shelf Length Restrictions
B: Facing Height minus 1/2 inch
C: Facing Width minus 1 inch
G: Return Depth Equals Facing Thickness plus 1/4 inch

Determining the Mantel Opening Height "B" (Based on Facing Height)

To determine the opening height "B" of any fireplace mantels, measure the height of the fireplace facing material (facing height) and subtract 1/2 inch to allow our fireplace mantels to overlap the facing material. (You can overlap the facing material up to two inches less than the breast "Z" if desired.)

Determining the Fireplace Mantel Width "C" (Based on Facing Width)

To determine the width "C" of the fireplace surround, measure the width of the facing material and subtract 1 inch. This allows the fireplace mantels to overlap the facing material 1/2 inch on each side. (You can overlap the facing material up to one inch less than the width of each mantel leg if needed.) *If ordering the Fremont, Sheridan, Anniston or Hawthorne mantel you can overlap the facing material up to two inches less than the width of each mantel leg if needed.)

Determining the Mantel Surround Return Depth "G" (Based on Facing Thickness)

All fireplaces have a front or face made of non-combustible material such as brick, tile, marble or slate. This facing material may be installed flush with the wall of the fireplace or it may protrude in front of the wall. The distance the facing material sticks out in front of the wall is the Facing Thickness. The return dimension "G" is calculated by adding a minimum of 1/4 inch to the thickness of the facing material protrusion. If you are building the fireplace mantel over 3/4 inch thick marble, you should specify a return depth of at least G=1 inch. Click here for an example of a G dimension graphic.

NOTE: If you select a G that is more than 1/2" deeper than your facing material thickness (e.g., for a deeper top shelf or for a "shadow box" look to your mantel) you must advise us so that we will know to send "extra deep" scribe molding.

Please note your:

  • Fireplace Mantel Shelf Length Restriction: Make sure that it is greater than "D" in the Mantel Dimension Diagram.
  • Hearth Length: If it is smaller than the "E" in the Mantel Dimension Diagram the legs of the fireplace mantels will not completely fit on top of the hearth. Email us for suggestions or click here for special situations.



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