Custom Mantels
Most of my adult life has been spent building furniture and cabinetry. I've built a few homes and contracted a number of additions and remodels. I currently spend my days crafting newels and balusters, kitchen island legs, etc. Saw dust surely runs through my veins. One project that always had my interest was creating custom mantels shelves and surrounds.
Mantels are a wonderful way to make a design statement. They are a focal point of sorts. Typically sofas and other accompanying pieces are situated around a fireplace to create a cozy area for conversation, reading or just relaxation. The mantel helps to frame the fireplace "in style". Other than being a way to show off your creativity, mantels provide a place to shelve your keepsakes and special pictures of family and friends. How many masterpiece paintings adorn the space above the world's mantels.
This is my first of several articles dealing with creating a masterpiece mantel. Let me begin by distinguishing between a mantel shelf and a mantel surround. The shelf sits above the fireplace only while the mantel surround wraps "surrounds" the fireplace. The difference are the "legs" of the surround that touch the floor unlike the shelf that is above. Pretty simple I know. Below is an image with the basic parts of a mantel surround.

The very first design consideration when contemplating your mantel is clearance. The wood that you are going to burn in the fireplace is not unlike the wood used to create your mantel. It will burn just as well so clearances are in order. If you purchasing a metal fireplace, your manufacturer will undoubtedly specify minimum clearances top and sides of the fireplace. If on the other hand, you having a mason custom build your fireplace, you or your builder should be aware of the local codes. A schematic will certainly be available from your local permit office. It will probably be based on the National Fire Protection Agency or NFPA.
The specifications will include the minimum depth of the hearth and the distance from the "firebox" to the edge of the hearth. These distances will probably vary depending on the square footage of the firebox.

Secondly the code will specify clearances between the
- Nearest wall and the edge of the fire box
- Between the fire box and the legs of the mantel if you are building a "surround"
- The vertical distance between the fire box and the mantel shelf and skirt
- And the width of the mantel shelf.
The allowable depth of the legs and mantel shelf will vary depending on the distance from the firebox. In other words, the further from the fire box, the wider the mantel shelf and mantel legs can be. (See illustration below)

So before you begin to design you mantel master piece do a little research to determine the minimums and clearances so that you will pass code and not be required to tear out your hard work.
More about custom mantels.